mixture test
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Questions and Answers

Which of the following is NOT a separation technique mentioned?

  • Filtration
  • Sublimation (correct)
  • Chromatography
  • Decanting

    • The separating funnel is used to separate two miscible liquids.

    False

    What is formed at the bottom of a centrifuge tube after spinning a mixture?

    Pellet

    In the separating funnel, the _______ liquid floats on top of the more dense liquid.

    <p>less dense</p> Signup and view all the answers

    Which method is used to separate different densities in a mixture, particularly in blood?

    <p>Centrifugation</p> Signup and view all the answers

    Floatation is a technique that can be used to remove plastic from water.

    <p>True</p> Signup and view all the answers

    What is the name of the liquid remaining above the pellet in a centrifuge tube?

    <p>Supernatant</p> Signup and view all the answers

    Oil floats on water because it is _______ than water.

    <p>less dense</p> Signup and view all the answers

    Match the separation technique with its description:

    <p>Filtration = Separates solids from liquids using a barrier Decanting = Pouring off a liquid to separate from solids Centrifugation = Uses rotational force to separate mixtures by density Floatation = Separates based on buoyancy, allowing lighter materials to rise</p> Signup and view all the answers

    Which of these techniques would be best for separating sand from water?

    <p>Filtration</p> Signup and view all the answers

    What is the purpose of a centrifugal separator?

    <p>To separate mixtures based on density</p> Signup and view all the answers

    Centrifuges were invented after hand-cranked separators became obsolete.

    <p>False</p> Signup and view all the answers

    What would happen if you put freshly collected blood in a centrifuge?

    <p>The components of the blood would separate into layers, such as plasma at the top and red blood cells at the bottom.</p> Signup and view all the answers

    A mixture of __________ and water can be separated using a separating funnel.

    <p>oil</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Centrifuge = A machine used to separate substances based on density Pellet = The solid that collects at the bottom of the centrifuge tube Supernatant = The liquid that remains above the pellet Separating Funnel = A device used to separate immiscible liquids based on density</p> Signup and view all the answers

    Before centrifugal separators were invented, how was cream separated from milk?

    <p>By letting it sit until the cream floated to the top</p> Signup and view all the answers

    The original centrifugal separators were completely automated.

    <p>False</p> Signup and view all the answers

    Describe how a centrifuge works to separate mixtures.

    <p>A centrifuge spins the mixture at high speed, causing denser materials to move outward, forming a pellet, while less dense materials remain in the liquid above.</p> Signup and view all the answers

    In a centrifuge tube, the __________ is the dense material that settles at the bottom after separation.

    <p>pellet</p> Signup and view all the answers

    Match the mixtures to their separation techniques:

    <p>Milk = Centrifuge Oil and water = Separating funnel Blood = Centrifuge Flour and water = Filtration</p> Signup and view all the answers

    Which of the following is an example of a colloid?

    <p>Milk</p> Signup and view all the answers

    An emulsion is a mixture of two or more soluble liquids.

    <p>False</p> Signup and view all the answers

    What is the main use of emulsifiers?

    <p>To keep immiscible liquids mixed evenly in an emulsion.</p> Signup and view all the answers

    A _______ consists of gas particles trapped within a liquid or solid.

    <p>foam</p> Signup and view all the answers

    Match the types of colloids with their descriptions:

    <p>Foam = Gas particles trapped in a liquid or solid Aerosol = Liquid or solid particles dispersed in a gas Emulsion = Two or more immiscible liquids mixed together Gel = Solid particles dispersed in a liquid</p> Signup and view all the answers

    What is the primary difference between a colloid and a suspension?

    <p>The size of the dispersed particles</p> Signup and view all the answers

    All colloids appear clear and do not scatter light.

    <p>False</p> Signup and view all the answers

    Name two examples of colloids.

    <p>milk, whipped cream</p> Signup and view all the answers

    A __________ is an example of an aerosol.

    <p>fog</p> Signup and view all the answers

    Match the types of mixtures with their descriptions:

    <p>Emulsion = A mixture of two liquids that do not mix Foam = A substance that is dispersed in gas Aerosol = A system of fine liquid droplets in a gas Gel = A semi-solid mixture with liquid trapped within its structure</p> Signup and view all the answers

    Which of the following would NOT be classified as a colloid?

    <p>Saltwater solution</p> Signup and view all the answers

    The Tyndall Effect demonstrates the scattering of light by __________ in a colloid.

    <p>particles</p> Signup and view all the answers

    Which of the following is an example of a heterogeneous mixture?

    <p>Chocolate chip cookies</p> Signup and view all the answers

    Homogeneous mixtures have components that are evenly distributed throughout the mixture.

    <p>True</p> Signup and view all the answers

    What is an emulsion?

    <p>A mixture of two immiscible liquids where one is dispersed in the other.</p> Signup and view all the answers

    An example of a ______________ mixture is sand and water.

    <p>heterogeneous</p> Signup and view all the answers

    Which of the following is a characteristic of a colloid?

    <p>Particles cannot be seen but scatter light</p> Signup and view all the answers

    Give an example of a homogeneous mixture.

    <p>Vinegar</p> Signup and view all the answers

    Match the type of mixture to their respective definitions:

    <p>Homogeneous = Components are evenly distributed throughout the mixture Heterogeneous = Components are unevenly distributed throughout the mixture Colloid = A mixture where one substance is dispersed evenly throughout another Solution = A homogeneous mixture where a solute is dissolved in a solvent</p> Signup and view all the answers

    Nitrogen and oxygen in the air is an example of a ____________ mixture.

    <p>homogeneous</p> Signup and view all the answers

    What is the mobile phase in the chromatography process described?

    <p>Water</p> Signup and view all the answers

    The Rf value for a substance is calculated by dividing the distance traveled by the substance by the distance traveled by the stationary phase.

    <p>False</p> Signup and view all the answers

    What is the term used to describe the distance the solvent travels in chromatography?

    <p>solvent front</p> Signup and view all the answers

    Dyes that do not move far up the stationary phase typically have a high affinity for the _______.

    <p>stationary phase</p> Signup and view all the answers

    Match the chromatography components with their definitions:

    <p>Stationary Phase = The medium that holds the substances in place Mobile Phase = The solvent that carries the substances Rf Value = Ratio of distance traveled by substance to solvent Solvent Front = The furthest point reached by the solvent</p> Signup and view all the answers

    If a different solvent, such as ethanol, is used in chromatography, what is likely to happen to the Rf values?

    <p>They will change, depending on the dyes</p> Signup and view all the answers

    All black ink pens contain the same dyes and will produce identical chromatograms.

    <p>False</p> Signup and view all the answers

    How should the baseline be drawn in chromatography and why?

    <p>It should be drawn with a pencil to avoid dissolving in the solvent.</p> Signup and view all the answers

    The formula for calculating an Rf value is Rf = _____ / _____

    <p>distance traveled by substance / distance traveled by solvent</p> Signup and view all the answers

    What is the purpose of the cooling process in distillation?

    <p>To condense the vapor back into a liquid</p> Signup and view all the answers

    Fractional distillation can only be used to separate liquids with the same boiling point.

    <p>False</p> Signup and view all the answers

    What is the final product collected from the distillation process of seawater?

    <p>Pure water or distillate</p> Signup and view all the answers

    In distillation, the _______ contains the pure liquid after the condensation process.

    <p>conical flask</p> Signup and view all the answers

    Match the parts of the distillation apparatus with their functions:

    <p>Round bottomed flask = Contains the liquid to be heated Condenser = Cools and condenses the vapor Retort stand = Supports the apparatus Jacket = Circulates cold water to cool the condenser</p> Signup and view all the answers

    Which of the following correctly describes the process of making a sugar solution?

    <p>Dissolving sugar in water</p> Signup and view all the answers

    Ethanol boils at a higher temperature than water.

    <p>False</p> Signup and view all the answers

    Name one alcoholic drink that is produced through distillation.

    <p>Vodka, whiskey, or rum</p> Signup and view all the answers

    During the process of distillation, the _______ is left behind in the boiling flask.

    <p>impurities or salt</p> Signup and view all the answers

    What is the term used for the liquid collected after condensation in the distillation process?

    <p>Distillate</p> Signup and view all the answers

    What process is used to separate pure water from saltwater?

    <p>Distillation</p> Signup and view all the answers

    Crystallisation is used when the solute is more important than the solvent.

    <p>True</p> Signup and view all the answers

    What is left behind when water is evaporated from saltwater?

    <p>Salt</p> Signup and view all the answers

    The process of obtaining pure water from saltwater involves _______.

    <p>distillation</p> Signup and view all the answers

    Match the following types of crystals with their examples:

    <p>Sugar crystals = Commonly grown in kitchens Alum crystals = Used in water purification Borax crystals = Used for cleaning products Epsom salt crystals = Commonly used in baths</p> Signup and view all the answers

    Which of the following crystals can be grown at home?

    <p>All of the above</p> Signup and view all the answers

    Saltwater can be separated using decanting and filtration.

    <p>False</p> Signup and view all the answers

    What happens to the water vapor during the distillation process?

    <p>It is cooled and condensed back into liquid.</p> Signup and view all the answers

    During distillation, water evaporates because it has a __________ boiling point than salt.

    <p>lower</p> Signup and view all the answers

    What is the primary energy source for the crystallization of table salt from salt lakes?

    <p>Energy from the Sun</p> Signup and view all the answers

    Which of the following is a benefit of recycling for landfill management?

    <p>Reduces the amount of waste sent to landfills</p> Signup and view all the answers

    Dross is a useful byproduct of aluminium recycling that is kept for reuse.

    <p>False</p> Signup and view all the answers

    What happens to aluminium cans after they are collected and squashed into bales?

    <p>They are sorted and prepared for melting down to be recycled.</p> Signup and view all the answers

    The process of separating metals from non-metals relies on the use of __________.

    <p>magnets</p> Signup and view all the answers

    Match the following separation processes with their corresponding materials:

    <p>Steel removal = Using magnets Glass separation = Using air jets Plastic sorting = Using infrared sensors Aluminium melting = High-temperature furnace</p> Signup and view all the answers

    What temperature must aluminium reach to melt?

    <p>660 °C</p> Signup and view all the answers

    Recycling aluminium uses more energy than producing new aluminium from raw materials.

    <p>False</p> Signup and view all the answers

    How many cans can be made with the energy used to create one new can from raw materials?

    <p>About 20 recycled cans.</p> Signup and view all the answers

    Dross is created during the melting process and it is often __________.

    <p>discarded</p> Signup and view all the answers

    How are different types of plastics separated in the recycling process?

    <p>By density and plastic identification codes</p> Signup and view all the answers

    Which metals are known to be magnetic?

    <p>Iron, nickel, and cobalt</p> Signup and view all the answers

    Aluminum cans can be separated from steel cans using a magnet.

    <p>False</p> Signup and view all the answers

    What type of magnet is used in recycling centers to move large pieces of metal?

    <p>electromagnet</p> Signup and view all the answers

    Only _____, nickel, and cobalt are known to be magnetic metals.

    <p>iron</p> Signup and view all the answers

    Match the following types of materials with their separability using magnets:

    <p>Iron = Can be separated using a magnet Plastic = Cannot be separated using a magnet Aluminum = Cannot be separated using a magnet Steel = Can be separated using a magnet</p> Signup and view all the answers

    What potential issue can arise from metal contamination in food processing?

    <p>Damage to equipment</p> Signup and view all the answers

    All metals are magnetic.

    <p>False</p> Signup and view all the answers

    What happens when an electromagnet is turned off?

    <p>It loses its magnetic properties.</p> Signup and view all the answers

    Magnets are used to separate _____ metals from non-magnetic materials in recycling centers.

    <p>ferrous</p> Signup and view all the answers

    What is one use of magnets in a scrap yard?

    <p>To separate iron from wood</p> Signup and view all the answers

    What does the mass of a solution equal when combining solute and solvent?

    <p>Sum of the mass of solute and solvent</p> Signup and view all the answers

    The volume of the solvent changes when a solute is added.

    <p>False</p> Signup and view all the answers

    What are the two components of a solution?

    <p>solute and solvent</p> Signup and view all the answers

    In the equation, 5ml of water + 1g of salt results in ____ml of saltwater solution.

    <p>6</p> Signup and view all the answers

    What effect does temperature have on solubility?

    <p>Higher temperatures generally increase solubility.</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Solute = The substance that is dissolved Solvent = The substance that dissolves the solute Solution = A homogeneous mixture of solute and solvent Conservation of mass = Mass is neither created nor destroyed in a chemical reaction</p> Signup and view all the answers

    A solute can be seen once it dissolves in a solvent.

    <p>False</p> Signup and view all the answers

    The mass of the solution is ____ to the sum of the mass of the solute and the mass of the solvent.

    <p>equal</p> Signup and view all the answers

    What happens to the spaces between solvent particles when a solute is added?

    <p>The solute particles fit into the spaces.</p> Signup and view all the answers

    What happens to gas solubility when pressure decreases?

    <p>Gas escapes from the solution</p> Signup and view all the answers

    Increasing the temperature of a solid solute will decrease its solubility.

    <p>False</p> Signup and view all the answers

    What occurs to the extra solute in a supersaturated solution when the temperature is lowered?

    <p>It forms crystals.</p> Signup and view all the answers

    The process of forming solids from a saturated solution as it cools is known as __________.

    <p>crystallization</p> Signup and view all the answers

    Match the following terms related to solubility with their definitions:

    <p>Supersaturated solution = Contains more solute than can typically dissolve Saturated solution = Contains the maximum amount of solute that can dissolve at a given temperature Solubility = The ability of a substance to dissolve in a solvent Crystallization = The formation of solid crystals from a solution</p> Signup and view all the answers

    What happens to the solubility of gases as temperature increases?

    <p>Decreases</p> Signup and view all the answers

    The solubility of solids in liquids typically decreases with temperature.

    <p>False</p> Signup and view all the answers

    What is a saturated solution?

    <p>A solution in which no more solute can dissolve at a given temperature and pressure.</p> Signup and view all the answers

    At 2 atmospheres of pressure, the solubility of carbon dioxide in water is _______ g/L.

    <p>15</p> Signup and view all the answers

    Match the conditions with their effects on gas solubility:

    <p>Increase in temperature = Decreases solubility Increase in pressure = Increases solubility Decrease in temperature = Increases solubility Decrease in pressure = Decreases solubility</p> Signup and view all the answers

    Which of the following describes a supersaturated solution?

    <p>Holds more solute than the normal solubility allows at a given temperature.</p> Signup and view all the answers

    Name an example of a mixture where a gas has dissolved in a liquid.

    <p>Carbonated drinks or ocean water.</p> Signup and view all the answers

    Which of the following describes a concentrated solution?

    <p>A high proportion of dissolved solute particles</p> Signup and view all the answers

    A dilute solution has a higher concentration than a concentrated solution.

    <p>False</p> Signup and view all the answers

    What is the saturation point of a solution?

    <p>The maximum amount of solute that can dissolve in a solvent at given conditions.</p> Signup and view all the answers

    The solubility of a substance refers to the amount of _______ that can dissolve in a given volume of solvent.

    <p>solute</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Dilute = Solution with low solute concentration Concentrated = Solution with high solute concentration Saturated = Solution that cannot dissolve more solute Solubility = Maximum amount of solute that can dissolve at given conditions</p> Signup and view all the answers

    Which of the following is an example of a dilute solution?

    <p>1g sugar in 100ml water</p> Signup and view all the answers

    A solution will always appear darker as it becomes more concentrated.

    <p>False</p> Signup and view all the answers

    What happens when a solution becomes supersaturated?

    <p>It contains more dissolved solute than it normally could at that temperature and pressure.</p> Signup and view all the answers

    If salt was continually added to a beaker of salt water and no more can dissolve, the solution is said to be _______.

    <p>saturated</p> Signup and view all the answers

    Match the following processes with their descriptions:

    <p>Crystallization = Formation of solid crystals from a supersaturated solution Dissolving = Process of solute mixing with solvent Supersaturation = State where a solution contains more solute than it can normally hold Saturation = Point where no more solute can dissolve in the solvent</p> Signup and view all the answers

    What is the process called when water is heated to leave solid salt behind?

    <p>Evaporation</p> Signup and view all the answers

    Chalk is a soluble substance in water.

    <p>False</p> Signup and view all the answers

    What do you call the solid particles that remain on the filter after filtration?

    <p>residue</p> Signup and view all the answers

    A mixture of salt and water forms a __________ when the salt is dissolved.

    <p>solution</p> Signup and view all the answers

    Match the filtering methods with their uses:

    <p>HEPA filters = Remove dust and pollen from air Coffee filters = Separate coffee grounds from liquid Aquarium filters = Clean water for fish Gas masks = Protect from smoke particles</p> Signup and view all the answers

    Which of the following is an example of an insoluble substance?

    <p>Chalk</p> Signup and view all the answers

    Filtration can separate liquids from soluble solids.

    <p>True</p> Signup and view all the answers

    What must be done to the air hole in a Bunsen burner before it is used for heating?

    <p>close it</p> Signup and view all the answers

    The liquid that passes through a filter during filtration is called the __________.

    <p>filtrate</p> Signup and view all the answers

    What is the role of a solvent in a solution?

    <p>To dissolve the solute</p> Signup and view all the answers

    What is the term used for the solid that dissolves in a solvent?

    <p>Solute</p> Signup and view all the answers

    The aqueous mixture formed by dissolving a solute in a solvent is called a solute.

    <p>False</p> Signup and view all the answers

    List two examples of soluble substances in water.

    <p>Salt and sugar</p> Signup and view all the answers

    In a mixture of chalk and water, chalk is considered __________ in water.

    <p>insoluble</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Solvent = The liquid that dissolves a solid Solute = The solid that dissolves in a solvent Solution = The mixture formed when a solute is dissolved in a solvent Suspension = A mixture where particles are dispersed in a liquid but not dissolved</p> Signup and view all the answers

    What is the primary purpose of decanting?

    <p>To separate a dense, insoluble solid from a liquid</p> Signup and view all the answers

    Filtration can separate very fine solid particles from liquids or gases.

    <p>True</p> Signup and view all the answers

    What technique is used to separate gravel from water and how does it work?

    <p>Decanting; it involves carefully pouring the liquid to leave the solid gravel behind.</p> Signup and view all the answers

    A sieve separates solids based on the size of their ________.

    <p>particles</p> Signup and view all the answers

    Match the following separation techniques with their appropriate description:

    <p>Decanting = Pouring liquid off from settled solids Sieving = Using a mesh to separate sizes Filtration = Separating fine solids from liquids Centrifugation = Using rapid spinning to separate components</p> Signup and view all the answers

    Which method would be the most efficient to separate a mixture of hazelnuts, peppercorns, and sugar?

    <p>Sieving</p> Signup and view all the answers

    Explain how decanting is applied in wine storage.

    <p>Wine is stored upright to allow solids to settle, then it is poured carefully to leave the sediment behind.</p> Signup and view all the answers

    What is the main purpose of filtration?

    <p>To separate an insoluble solid from a liquid</p> Signup and view all the answers

    In a solution, the solid particles are visible and suspended in the liquid.

    <p>False</p> Signup and view all the answers

    What are the two components formed when a mixture of sand and water is filtered?

    <p>Residue and filtrate</p> Signup and view all the answers

    When a mixture of sand and water is filtered, the ________ is left on the filter paper.

    <p>sand</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Filtrate = The liquid that passes through filter paper Residue = The solid left behind after filtration Suspension = A mixture where solid particles are mixed in a liquid Sediment = Solid particles that settle at the bottom of a liquid</p> Signup and view all the answers

    In the green mix experiment, which particles were found to be soluble?

    <p>Blue particles</p> Signup and view all the answers

    Suspensions consist of solid particles that have dissolved in a liquid.

    <p>False</p> Signup and view all the answers

    What happens to insoluble particles in a suspension if left undisturbed?

    <p>They either sink to the bottom or rise to the top.</p> Signup and view all the answers

    Chalk and water can be separated using ________ to collect the filtrate.

    <p>filter paper</p> Signup and view all the answers

    What will form at the bottom of a beaker after filtering a mixture of chalk and water?

    <p>Residue</p> Signup and view all the answers

    Which of the following is an example of a pure substance?

    <p>A gold ring</p> Signup and view all the answers

    Impure substances can only consist of solid particles.

    <p>False</p> Signup and view all the answers

    What are mixtures often made of?

    <p>Different types of particles</p> Signup and view all the answers

    A _______ is a physical combination of two or more pure substances.

    <p>mixture</p> Signup and view all the answers

    Match the following examples with their type:

    <p>Iron = Pure substance Air = Mixture Salt water = Mixture Oxygen = Pure substance</p> Signup and view all the answers

    Which technique can be used to separate a mixture based on particle size?

    <p>Filtration</p> Signup and view all the answers

    Mixtures can only be separated through chemical methods.

    <p>False</p> Signup and view all the answers

    Name a characteristic of pure substances.

    <p>They have only one type of particle.</p> Signup and view all the answers

    When salt is dissolved in water, it forms a _______.

    <p>solution</p> Signup and view all the answers

    Which of the following options describes a characteristic of mixtures?

    <p>They can be separated by physical means.</p> Signup and view all the answers

    Study Notes

    Separation Techniques

    • Sieving: separates particles based on size.
    • Decanting: separates liquids from solids by pouring off the liquid.
    • Magnets: separates magnetic materials from non-magnetic materials.
    • Filtration: separates solids from liquids using a filter with holes.
    • Evaporation: separates dissolved solids from a liquid by heating and leaving it to evaporate.
    • Distillation: separates liquids with different boiling points by heating and collecting the vapor.
    • Chromatography: separates components based on their different affinities for a stationary phase and a mobile phase.

    Floatation

    • Plastics float on water and can be scooped out with a net.

    Separating Funnel

    • Used to separate immiscible liquids (liquids that do not mix).
    • The less dense liquid floats on top.
    • The tap is opened to drain the denser liquid into a beaker.
    • The less dense liquid is then drained into a different beaker.

    Centrifuge

    • A machine that creates a rotational force.
    • Used to separate particles of different densities.
    • After spinning, the denser particles form a pellet at the bottom of the tube.
    • The liquid remaining on top is called supernatant.
    • The supernatant can be spun at a faster speed for further separation.

    Centrifuging Blood

    • When centrifuging blood, the red blood cells form a pellet at the bottom.
    • Plasma, the less dense liquid, remains on top.

    Centrifuging Milk

    • Centrifuges separate cream from milk based on density.
    • The cream floats to the top due to its lower density.
    • Before centrifuges, milk was separated by hand.
    • Centrifuges made the separation process faster and easier, preventing milk from turning sour.

    Centrifuging Mixtures

    • Mixtures containing particles of different densities can be separated by centrifuging.
    • At low speeds, the largest particles form a pellet at the bottom.
    • By repeatedly centrifuging the supernatant, the next largest particles can be isolated.

    Centrifuge Tube

    • The pellet is at the bottom of the tube.
    • The supernatant is the liquid above the pellet.

    Mixtures

    • Mixtures are easier to separate than pure substances, which include compounds and elements.
    • Mixtures can be classified as homogenous or heterogenous.
    • Homogenous mixtures have particles evenly distributed and include examples like: nitrogen and oxygen in air, steel, vinegar, brass, black coffee, natural gas.
    • Heterogenous mixtures have components scattered unevenly and include examples like: salad, chocolate chip cookies, soda with ice.

    Types of Mixtures

    • Solutions contain particles that completely dissolve.
    • Colloids contain small suspended particles that are too small to settle or be removed by filtering.
    • Suspensions contain larger particles.
    • Emulsions are a specific type of colloid with two or more insoluble liquids, where one liquid disperses evenly through the other instead of settling into layers.

    Colloids

    • Colloids are cloudy and can be formed by solids, liquids, or gases.
    • Examples of colloids include: milk, mist, cappuccino froth, whipped cream, ice-cream, paint, styrofoam, and ink.
    • Colloids are classified as foams, aerosols, emulsions, gels, or sols, depending on the dispersed phase and dispersion medium.
    • Emulsions are colloids formed by two or more insoluble liquids.
    • Emulsifiers are chemicals added to immiscible liquids to keep them dispersed as an emulsion.
    • Lecithin in egg yolk is an emulsifier used in mayonnaise.
    • Water and oil are immiscible, meaning they do not mix.
    • The Tyndall Effect is the scattering of light by particles in a colloid or suspension. It makes a light beam visible through a colloid or suspension, but not through a solution.
    • The size of particles differentiates a colloid from a suspension.
    • Colloids have particles between 1-1000 nanometers.
    • Suspensions have particles between 10-1000 micrometers.
    • Solutions are clear, while colloids and suspensions appear cloudy.

    Homogenized vs Unhomogenized Milk

    • Unhomogenized milk has a layer of cream floating on top because it isn't an emulsion.
    • Homogenized milk is an emulsion because the fat particles have been dispersed evenly throughout the liquid.

    Examples of Colloids

    • Foams: Shaving cream, whipped cream
    • Aerosols: Mist, fog, hairspray, smoke, ice cloud
    • Emulsions: Milk, mayonnaise, hand lotion, moisturizer, salad dressing
    • Gels: Gelatin, agar, jelly, butter
    • Sols: Ink, paint, colored gems

    Macaroni Salad Colloids

    • The mustard is likely a suspension, as it can settle out.
    • The vinegar in the dressing is a solution.
    • The mayonnaise and creamy dressing are likely emulsions.

    Chromatography

    • Stationary phase: The paper
    • Mobile phase: The water
    • Capillary action: The term used to describe the way the solvent moves up the stationary phase
    • Baseline: Drawn using a pencil to avoid dissolving in the solvent
    • Soluble dyes: Dyes that move a long way up the stationary phase are more soluble in the solvent
    • Insoluble dyes: Dyes that do not move very far have a stronger affinity for the stationary phase
    • Solvent front: Drawn at the furthest point the solvent has reached in the stationary phase
    • Chromatograms: Chromatograms for two different pens will likely show different separation patterns & distances travelled by dyes if the inks are composed of different dyes
    • Rf value formula: Rf=distancetravelledbysubstancedistancetravelledbysolventR_f = \frac{distance travelled by substance}{distance travelled by solvent}Rf​=distancetravelledbysolventdistancetravelledbysubstance​
    • Rf values and solvents: Rf values can change if a different solvent is used. Each solvent has a different polarity which affects the solubility of the dyes.
    • Rf values in examples:
      • Spot X Rf value = 0.86
      • Spot Y Rf value = 0.67
      • Spot Z Rf value = 0.53

    Crystallisation

    • Crystallisation is a separation process where the solute is collected instead of the solvent.
    • Table salt is produced by crystallisation, using sunlight to evaporate water from salt lakes.
    • Copper sulphate crystals can be obtained by slowly evaporating a solution over time, leaving it exposed to air.

    Distillation

    • Distillation is a method for separating solvents from a solution.
    • Distillation works because the solvent has a lower boiling point than the solute.
    • When the solution is heated, the solvent evaporates.
    • The evaporated solvent is then cooled and condensed back into a liquid.
    • Distillation is used to make pure water from saltwater.

    Simple Distillation

    • Simple distillation is used to separate a solvent from a solution when the solute has a much higher boiling point.
    • In laboratory settings, saltwater is poured into a boiling flask and heated to 100°C.
    • The water evaporates and becomes steam.
    • The steam travels along a condenser, where it is cooled below 100°C and condenses back into liquid water.
    • The condenser is kept cool by running cold water through its outer jacket.
    • The pure water collected is called the distillate.

    Fractional Distillation

    • Fractional distillation is used to separate liquids with different boiling points.
    • It works because the liquid with the lower boiling point evaporates first.
    • Fractional distillation is used to separate ethanol from a mixture of ethanol and water.
    • This method is also used in the production of spirits, where ethanol is vaporized and collected to create a higher alcohol content.

    Examples

    • Wine and beer are not distilled.
    • Spirits like vodka, rum, and whiskey are obtained by distillation.

    Recycling

    • Recycling reduces the amount of waste sent to landfills and conserves natural resources.

    • Pre-sorting removes materials that cannot be recycled, such as food waste. Materials are identified by their size, shape, and composition.

    • The trommel separates materials based on their size. Larger items are sorted first, then smaller items are sifted through screens.

    • Steel cans are separated using a magnetic drum that attracts the ferrous metal.

    • Aluminium cans are separated using an eddy current separator, which creates a magnetic field that repels the non-ferrous metal.

    • Glass is separated from other materials using a combination of size, shape, and density.

    • Plastic is separated into different types using a variety of technologies that take advantage of their varying properties.

    • Recycled aluminium can be used to make 20 cans using the same amount of energy as making one new can from raw materials.

    Aluminium Can Recycling

    • Squashed cans are first sorted to remove materials that cannot be recycled.

    • Metal is sorted from non-metal using conveyor belts with electromagnets that separate ferrous from non-ferrous metals.

    • Plastic and glass are removed by hand or by machine, depending on the size of the pieces.

    • Steel is removed using a magnetic drum that attracts the ferrous metal.

    • Aluminium melts at 660 degrees Celsius.

    • The furnace that melts the aluminium chips reaches a temperature of around 1000 degrees Celsius.

    • One furnace can hold approximately 50000 lbs. of aluminum chips.

    • Dross is a slag-like material that forms on top of molten aluminium, it can be recycled.

    • 50,000 cans can be melted down to make one ingot.

    • Aluminium is expensive because it is energy-intensive to produce from raw materials.

    Separating Mixtures

    • Sand, iron nails, and plastic beads can be separated based on their properties.
    • A magnet can be used to separate iron from a mixture.

    Magnetism

    • Not all metals are magnetic.
    • Only iron, nickel, and cobalt are magnetic.
    • Alloys of iron, nickel, and cobalt are also magnetic.
    • Steel is an alloy of iron and carbon, making it magnetic.
    • Aluminum is not magnetic, allowing for separation from steel.

    Uses of Magnets

    • Magnets are used in recycling centers to separate steel from aluminum, glass, cardboard, and plastic.
    • Magnets in scrap yards separate iron from wood and other materials like rubber tires.
    • Electromagnets utilize electricity to create a magnetic field which can be turned on and off for picking up and dropping metal.

    Magnets and Food Standards

    • Magnets are crucial for preventing metal contamination in food production.
    • Metal contaminants can arise from broken equipment, screws, or shavings.
    • Metal contaminants can damage equipment and cause costly repairs and downtime.
    • Contaminated food can harm consumers and damage the manufacturer's reputation.
    • Conveyor belts with magnets are used to detect and remove metal contaminants from foods.

    Dissolving

    • The solvent is a liquid with small spaces between particles.
    • The solute particles can fit into these spaces.
    • The volume of the solvent is equal to the volume of the solution.
    • The level of liquid in a beaker remains the same before and after adding a soluble solute.

    Mass

    • The mass of a solution is equal to the mass of the solute plus the mass of the solvent.
    • This is known as the conservation of mass.
    • The mass of the solute is not lost when it dissolves; the particles are just too small to see.

    Further considerations

    • When a solution/solute is added to a solvent, the total volume/mass of the solvent does not change.
    • Dilute solutions have a low concentration of solute.
    • Concentrated solutions have a high concentration of solute.
    • The solubility of different substances varies; 5g of water may dissolve 1g of salt but not 1g of another substance.
    • The solubility of a substance can be affected by temperature.
    • When all the spaces between solvent particles are occupied, the solute can no longer dissolve.

    Dilute and Concentrated Solutions

    • Dilute solutions have a low proportion of dissolved solute particles.
    • Concentrated solutions have a high proportion of dissolved solute particles.

    Creating Dilute & Concentrated Solutions

    • Method 1: Keep the mass of the solute the same & change the volume of the solvent.
      • E.g. 10g sugar in 1000ml of water (dilute) vs 10g sugar in 100ml of water (concentrated)
    • Method 2: Keep the volume of the solvent the same & change the mass of the solute.
      • E.g. 1g sugar in 100ml of water (dilute) vs 10g sugar in 100ml of water (concentrated)

    Saturated Solutions

    • A saturated solution is a solution containing the maximum possible amount of dissolved solute at a given temperature and pressure.
    • No more solute will dissolve in a saturated solution.
    • The amount of solute that can dissolve in a particular solvent before a solution becomes saturated is referred to as its solubility.
    • Solubility depends on both the solute and the solvent.
    • For example, the solubility of salt in water is 360 g/L, meaning a maximum of 360g of salt can dissolve in 1L of water.

    Effect of Temperature on Solubility

    • Generally, the solubility of solids increases with increasing temperature.
      • E.g. copper sulfate solubility in water is 320g/L at 20°C but increases to 620g/L at 60°C.
    • Generally, the solubility of gases decreases with increasing temperature.
      • E.g. carbon dioxide solubility in water is 1.7g/L at 20°C, but decreases to 0.6g/L at 60°C.

    Effect of Pressure on Solubility

    • Generally, the solubility of gases increases with increasing pressure.
    • This does not apply to solids.
      • E.g. at 20°C, the solubility of carbon dioxide in water increases from 1.7g/L at 1 atmosphere of pressure to 15g/L at 2 atmospheres of pressure.

    Supersaturated Solutions

    • A supersaturated solution contains more dissolved solute than it can normally hold at a given temperature and pressure.
    • This is achieved by increasing temperature (for solids) or pressure (for gases) and then cooling the solution or reducing the pressure.
    • As the temperature or pressure decreases, the extra solute will come out of solution, leading to crystal formation (solids) or gas escaping (gases).
    • Supersaturated sugar solutions are used in confectionery production, as the excess sugar crystallizes upon cooling.
    • Fizzy drinks are supersaturated with carbon dioxide gas, which escapes when the pressure is reduced upon opening the bottle.

    Separating Mixtures

    • Mixture: a combination of two or more substances where each substance keeps its own properties
    • Solvent: a substance that dissolves another substance
    • Soluble: capable of dissolving in a solvent
    • Dissolve: to mix evenly into a solvent
    • Solution: a mixture where a soluble substance has dissolved in a solvent
    • Insoluble: not capable of dissolving in a solvent
    • Sediment: solid particles that settle to the bottom of a suspension
    • Particles: small pieces of matter
    • Suspension: a mixture where insoluble particles are spread throughout a liquid
    • Filter: a material that allows some substances to pass through but blocks others
    • Large: a size that is not small
    • Filtrate: the liquid that passes through a filter
    • Residue: the solid material that is left behind on a filter

    Decanting

    • Decanting: a method of separating a mixture by carefully pouring the liquid off the top, leaving the solid residue behind
    • Decanting is used for separating mixtures where the solid settles at the bottom

    Sieving

    • Sieving: a method of separating particles of different sizes
    • Sieving uses a device called a sieve
    • Sieving is used to separate larger particles from smaller ones

    Filtration

    • Filtration: a method of separating a solid from a liquid by passing the mixture through a filter
    • The liquid that passes through the filter is called the filtrate
    • The solid particles that remain on the filter are called the residue

    Evaporation

    • Evaporation: a method of separating a dissolved solid from a liquid solvent by heating the solution.
    • The liquid solvent evaporates, leaving the solid behind
    • Evaporation is used to separate salt from water, or to separate sugar from water.

    Bunsen Burner

    • Bunsen Burner: a tool used to heat substances
    • The Bunsen burner has an air hole that can be adjusted to control the flame
    • A blue flame is hotter than a yellow flame.
    • A tripod, gauze mat, and evaporating dish are needed to use a Bunsen burner

    Filters

    • Water filters: Remove impurities from water for drinking
    • Coffee filters: Separate coffee grounds from brewed coffee
    • Tea bags: Separate tea leaves from brewed tea
    • Air conditioners and vacuum cleaners: Use HEPA filters to remove dust and pollen from the air
    • Aquariums: Use filters to clean the water for fish
    • Fire fighters: Use gas masks with filters to remove smoke particles
    • Carbon based filters: Remove impurities from tap water

    Decanting

    • Decanting is a method for separating a dense, insoluble solid from a liquid.
    • The solid sinks to the bottom of the container and forms a sediment.
    • The liquid is poured into a new container, leaving the solid behind.
    • Decanting is only useful if the solid particles readily settle to the bottom.
    • It is used to separate wine from sediment after it has been stored horizontally.

    Sieving

    • Sieving separates a dry mixture of two solids with different particle sizes.
    • A sieve with holes small enough to allow one particle through but not the other is used.
    • It can be used to separate hazelnuts, peppercorns, and sugar.
    • A colander is a type of sieve used to separate pasta from water.

    Filtration

    • Filtration separates very fine solid particles from liquid or gas mixtures.
    • Filter paper with very fine pores acts as a sieve.
    • It is used to separate an insoluble solid from a liquid.
    • Sand and water are an example of a mixture that can be separated by filtration.
    • The sand remains in the filter paper (residue) and the water passes through (filtrate).

    Suspensions

    • A suspension is a mixture of very small solid particles in a liquid that do not dissolve.
    • The solid particles will separate from the liquid over time, either sinking to the bottom or rising to the top.
    • Sand in water and chalk in water are examples of suspensions.
    • Suspensions may separate quickly or stay suspended for a long time, depending on their contents.
    • In a solution, particles have dissolved and cannot be seen.
    • In a suspension, particles have not dissolved and are mixed within the liquid.

    Equipment

    • A funnel is used to hold the filter paper during filtration.
    • A beaker or conical flask can be used to collect the filtrate.

    Solutions

    • When a substance dissolves, it is said to be soluble.
    • The liquid that dissolves the substance is called the solvent.
    • The solid substance that dissolves is called the solute.
    • The resulting mixture is called a solution.
    • Salt dissolves in water to form a salt water solution.
    • Salt is the solute and water is the solvent.

    Pure Substances

    • Only have one type of particle
    • Example: Gold ring
    • Found on the Periodic Table

    Impure Substances

    • Also called Mixtures
    • Have more than one type of particle
    • Examples: Air, bucket of sand and stones, cappuccino, mocha, blood

    Mixtures

    • Different states of matter can be mixed
    • Examples: Solids mixed with other solids, solids mixed with liquids, liquids mixed with other liquids, gases mixed with other gases, gases mixed with liquids

    Separating Mixtures

    • Chemists use various techniques to separate mixtures based on particle properties:
      • Size
      • Mass
      • Solubility (ability to dissolve)
      • Boiling Point
    • Separation methods can be physical or chemical

    Physical Combinations

    • Mixtures are a result of physical combinations of pure substances
    • Components of a mixture do not change into other substances
    • Example: Mixing copper sulfate powder with water creates a solution but does not create a new substance
    • Mixtures can be separated physically
    • Example: Boiling a copper sulfate solution evaporates the water, leaving behind copper sulfate powder

    Key Points

    • Pure substances have only one type of particle.
    • Impure substances are mixtures of different types of particles.
    • Mixtures are physical combinations of pure substances and can be separated physically.

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    Pure Substances and Mixtures PDF
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