Separation Techniques in Science

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Questions and Answers

What is the primary principle behind separating cream from milk using a centrifuge?

Evaporation of the liquid

Filtration through a porous membrane

Separation based on density (correct)

Separation based on chemical properties

What is a disadvantage of using traditional methods to separate cream from milk before the invention of centrifuges?

It required expensive equipment.

It resulted in curdled milk.

It took a long time for the cream to rise. (correct)

It was more hygienic than modern methods.

In a centrifuge, what happens to the components of a mixture during the spinning process?

It causes chemical reactions that change the mixture.

All components evaporate into gas.

The heavier components settle faster than the lighter ones. (correct)

No separation occurs; everything stays mixed.

What is likely to happen if freshly collected blood is placed in a centrifuge?

It will separate into layers including plasma and red blood cells. Signup and view all the answers

How does the use of a separating funnel differ from that of a centrifuge in separating oil and water?

A separating funnel depends on gravity while a centrifuge uses centrifugal force. Signup and view all the answers

What is the primary purpose of using a separating funnel?

To separate two immiscible liquids of different densities Signup and view all the answers

Which separation technique utilizes a rotational force for separation?

Centrifugation Signup and view all the answers

What occurs to the less dense liquid when using a separating funnel?

It floats on top of the denser liquid Signup and view all the answers

After centrifuging a mixture, what is the name of the solution that remains on top of the pellet?

Supernatant Signup and view all the answers

Which separation technique would be best suited for separating a heterogeneous mixture of sand and salt?

Filtration Signup and view all the answers

What happens to the particles in a centrifuge during centrifugation?

The denser particles form a pellet at the bottom Signup and view all the answers

Which of the following separation techniques is specifically used for separating colored substances in a mixture?

Chromatography Signup and view all the answers

When performing decantation, what is typically removed?

The liquid above the solid particles Signup and view all the answers

What are some separation techniques that have been learned so far?

Sieving, decanting, magnets, filtration, evaporation, distillation, chromatography, floatation, separating funnel, centrifuge Signup and view all the answers

How does a separating funnel work?

It separates two immiscible liquids of different densities by allowing the less dense liquid to float on top. Signup and view all the answers

What forms when a mixture is spun in a centrifuge?

A pellet from the more dense particles and a supernatant on top. Signup and view all the answers

The less dense liquid sinks to the bottom in a separating funnel.

False Signup and view all the answers

What happens when freshly collected blood is placed in a centrifuge?

The blood components separate based on density, forming a pellet of red blood cells at the bottom and plasma as the supernatant. Signup and view all the answers

What happens if freshly collected milk is placed in a centrifuge?

The cream separates from the milk and rises to the top as a supernatant. Signup and view all the answers

A mixture of oil and water can be separated using a ______.

separating funnel Signup and view all the answers

Match the following items with their description:

Separating Funnel = Used to separate two immiscible liquids Centrifuge = Machine that uses rotational force to separate mixtures Pellet = Formed from more dense particles during centrifugation Supernatant = Liquid remaining on top after centrifugation Signup and view all the answers

What is the primary function of a centrifuge?

To separate mixtures based on density Signup and view all the answers

Centrifuging separates components of a mixture by adding heat to the process.

False Signup and view all the answers

Describe the process of separating a mixture of oil and water using a separating funnel.

Oil will float on top of water due to being less dense. Open the tap to let the water drain from the bottom, leaving the oil in the funnel. Signup and view all the answers

Which separation technique is used to separate a solid from a liquid by passing the mixture through a barrier that allows only the liquid to pass?

Filtration Signup and view all the answers

A ______ is used to accelerate the separation of components in a liquid mixture by spinning it at high speeds.

centrifuge Signup and view all the answers

Match the following processes with their descriptions:

Centrifugation = Separation based on density using rotational force Decantation = Pouring off a liquid from sediment Separating Funnel = Separation of immiscible liquids Sedimentation = Allowing particles to settle out of a liquid Signup and view all the answers

A separating funnel can be used to separate two liquids that mix together.

False Signup and view all the answers

What is the term for the liquid that remains on top after centrifuging a mixture?

supernatant Signup and view all the answers

Which component would form the pellet when freshly collected blood is put in a centrifuge?

Red blood cells Signup and view all the answers

The process of using a machine to spin a mixture and separate particles based on density is called ______.

centrifugation Signup and view all the answers

Centrifuging milk could lead to the cream separating and floating on top of the milk.

True Signup and view all the answers

Match the separation technique with its description:

Sieving = Separating based on size through a mesh Decanting = Pouring off a liquid, leaving solids behind Floatation = Using buoyancy to separate substances based on density Chromatography = Separating substances based on their different affinities for a stationary phase Signup and view all the answers

What happens when freshly collected milk is placed in a centrifuge?

The cream separates from the milk and rises to the top due to being less dense. Signup and view all the answers

Before the invention of centrifuges, separation of cream from milk relied on letting the milk ______.

sit Signup and view all the answers

Which separation technique would be most effective for separating sand from salt?

Filtration Signup and view all the answers

What are two benefits of using a centrifugal separator compared to traditional methods of separation?

Centrifugal separators allow for faster separation and reduce the risk of spoilage while the milk sits. Signup and view all the answers

Oil is denser than water and will sink when placed into a separating funnel.

False Signup and view all the answers

What happens to the more dense particles when a mixture is spun in a centrifuge?

They form a pellet at the bottom. Signup and view all the answers

In a separating funnel, the ______ liquid can be tapped off from the bottom.

more dense Signup and view all the answers

Which technique involves using a net to remove floating plastic from water?

Floatation Signup and view all the answers

What distinguishes a colloid from a suspension in terms of particle visibility?

In a colloid, the particles are not visible to the naked eye, whereas in a suspension, the particles are larger and can settle out, making them visible. Signup and view all the answers

Define an emulsion and provide an example.

An emulsion is a mixture of two immiscible liquids where one is dispersed in the other; for example, mayonnaise is an emulsion of oil and vinegar. Signup and view all the answers

Explain the Tyndall effect and how it can be used to differentiate between a colloid and a solution.

The Tyndall effect is the scattering of light by particles in a medium; it can be observed in colloids, which scatter light, while solutions do not. Signup and view all the answers

List the main differences between colloids and suspensions in terms of stability and particle size.

Colloids have smaller particle sizes that remain evenly distributed and stable, while suspensions contain larger particles that can settle over time. Signup and view all the answers

Why are homogeneous mixtures considered uniform, and how does this relate to the definition of a colloid?

Homogeneous mixtures are uniform in composition, just like colloids where the dispersed particles are evenly distributed throughout the medium. Signup and view all the answers

What distinguishes a colloid from a suspension in terms of particle size?

Colloids contain smaller particles that do not settle out while suspensions contain larger particles that can settle out. Signup and view all the answers

How do emulsifiers function in a combination of two immiscible liquids?

Emulsifiers stabilize the mixture by reducing surface tension and preventing the liquids from separating into layers. Signup and view all the answers

What is the Tyndall effect and how does it relate to colloids?

The Tyndall effect is the scattering of light by particles in a colloid, making the mixture appear cloudy. Signup and view all the answers

List two examples of colloids and explain their characteristics.

Examples include milk and fog; both are cloudy mixtures containing small particles suspended within a liquid or gas. Signup and view all the answers

What is the main difference between a gel and a sol within colloids?

A gel is a colloid with solid particles dispersed in a liquid, while a sol consists of liquid particles dispersed in a solid. Signup and view all the answers

Explain why unhomogenized milk is not classified as an emulsion.

Unhomogenized milk separates into layers, with cream floating on top, indicating the liquids are not fully dispersed. Signup and view all the answers

Identify and describe two types of colloids based on their dispersed phase and dispersion medium.

Aerosols contain solid or liquid particles dispersed in a gas, while foams consist of gas particles trapped in a liquid or solid. Signup and view all the answers

How does the particle size in colloids affect their stability compared to suspensions?

The smaller particles in colloids remain suspended due to Brownian motion, preventing settling, unlike larger particles in suspensions which do settle. Signup and view all the answers

What type of dispersion medium is found in foams?

Gas Signup and view all the answers

What is the size range of the particles in a colloid?

1-1000 nanometers Signup and view all the answers

How does the Tyndall Effect demonstrate the presence of colloidal particles?

It shows light scattering by the particles, making a beam visible. Signup and view all the answers

What distinguishes emulsions from other types of colloids?

Emulsions consist of liquid droplets dispersed in another liquid. Signup and view all the answers

In what way can suspensions be visually differentiated from colloids?

Suspensions are cloudy and may settle over time, unlike colloids that remain dispersed. Signup and view all the answers

What type of dispersed phase is found in solid foams?

Solid Signup and view all the answers

What is the primary distinguishing feature between a colloid and a suspension regarding particle size?

Colloids have particles ranging from 1 to 1000 nanometers, while suspensions have larger particles. Signup and view all the answers

Can solutions exhibit the Tyndall Effect? Why or why not?

No, because solutions have particles that are too small to scatter light. Signup and view all the answers

What is a common example of a solid sol, and how is it classified?

Coloured gems, classified as solids dispersed in a solid medium. Signup and view all the answers

Which colloid type is formed when liquid droplets are suspended in gas?

Aerosol Signup and view all the answers

What distinguishes an emulsion from other types of colloids?

An emulsion specifically involves two or more insoluble liquids, where one liquid spreads evenly through another. Signup and view all the answers

What is the role of emulsifiers in emulsions?

Emulsifiers are chemicals added to keep immiscible liquids dispersed as an emulsion. Signup and view all the answers

How do colloids differ from solutions in terms of visibility of particles?

Colloids and suspensions are cloudy, while solutions appear clear due to smaller particle size. Signup and view all the answers

What is the Tyndall effect and how does it relate to colloids?

The Tyndall effect is the scattering of light by colloidal particles, making light beams visible in colloids. Signup and view all the answers

Provide an example of a colloid and explain its classification.

Milk is a colloid classified as an emulsion due to the dispersion of fat globules in water. Signup and view all the answers

Why is unhomogenised milk not considered an emulsion?

Unhomogenised milk has a layer of cream floating on top, indicating separation rather than a uniform mixture. Signup and view all the answers

What is an example of a colloid that is a foam, and how is it formed?

Whipped cream is an example of a foam, formed by trapping air in liquid cream during whipping. Signup and view all the answers

Describe the difference between emulsions and suspensions.

Emulsions consist of two immiscible liquids that remain evenly dispersed, while suspensions contain larger particles that can settle. Signup and view all the answers

What type of mixture is mayonnaise, and what two components classify it?

Mayonnaise is an emulsion, composed of oil and vinegar, stabilized by emulsifiers like egg yolk. Signup and view all the answers

Identify a common misperception about colloids and provide clarification.

A common misperception is that all colloids are cloudy; however, some, like clear gels, can be transparent. Signup and view all the answers

What is the stationary phase and the mobile phase when separating black ink on paper using water?

The stationary phase is the paper, and the mobile phase is water. Signup and view all the answers

What term describes the way the solvent moves up the stationary phase?

This is called capillary action. Signup and view all the answers

How should the base line be drawn in chromatography and why?

The base line should be drawn with a pencil to avoid interference from ink, which can affect results. Signup and view all the answers

What does it suggest about a dye that moves a long way up the stationary phase in terms of its solubility?

It suggests that the dye is highly soluble in the solvent. Signup and view all the answers

What can you infer about the dyes that do not move far along the stationary phase regarding their affinity for it?

They have a high affinity for the stationary phase. Signup and view all the answers

Where should the solvent front be marked on the chromatogram?

The solvent front should be marked at the highest point reached by the solvent. Signup and view all the answers

When comparing the chromatograms of two different black ink pens, what differences might you observe?

You would likely see varying numbers of spots and different distances travelled by each dye. Signup and view all the answers

What is the formula to calculate the Rf value in chromatography?

The formula is $Rf = \frac{distance \ traveled \ by \ substance}{distance \ traveled \ by \ solvent}$. Signup and view all the answers

If a different solvent like ethanol were used instead of water, would the Rf values be the same?

No, the Rf values would likely differ because Rf depends on the solvent used. Signup and view all the answers

What characterizes a pure substance compared to a mixture?

A pure substance contains only one type of particle, while a mixture contains two or more types of particles. Signup and view all the answers

Give an example of a pure substance and explain why it qualifies as such.

Gold is an example of a pure substance because it consists entirely of gold atoms without any impurities. Signup and view all the answers

What is one method chemists use to separate mixtures, and how does it work?

Chemists often use filtration to separate mixtures by passing the mixture through a barrier that allows only certain particles to pass. Signup and view all the answers

Explain why mixtures can be physically separated.

Mixtures consist of components that are not chemically bonded, allowing them to retain their individual properties and be separated physically. Signup and view all the answers

What happens to the properties of substances when they form a mixture?

The properties of the individual substances remain unchanged in a mixture; they do not create new substances. Signup and view all the answers

Why can blood be considered a mixture rather than a pure substance?

Blood is considered a mixture because it contains different types of cells and plasma, which can be physically separated. Signup and view all the answers

List the types of mixtures based on physical states.

Mixtures can be solids with solids, liquids with liquids, gases with gases, or combinations of these states. Signup and view all the answers

What role does solubility play in separating mixtures?

Solubility helps determine which components can dissolve in a solvent, allowing for separation methods like crystallization. Signup and view all the answers

Describe how a copper sulfate solution can be separated into its components.

A copper sulfate solution can be separated by evaporating the water, leaving behind the copper sulfate crystals. Signup and view all the answers

In what ways can the physical properties of particles affect separation techniques?

Physical properties such as size, mass, and boiling point influence the choice of separation techniques like centrifugation or distillation. Signup and view all the answers

What is the main difference between sieving and filtration in terms of the types of materials they separate?

Sieving separates larger solid particles from smaller ones based on size, while filtration removes very fine solid particles from liquids or gases. Signup and view all the answers

In the context of mixtures, what are suspensions and how do they differ from solutions?

Suspensions are heterogeneous mixtures where solid particles are suspended in a liquid, whereas solutions are homogeneous mixtures where a solute is fully dissolved in a solvent. Signup and view all the answers

How would you use a sieve to separate a mixture of flour and coarse sand?

You would choose a sieve with holes small enough to allow flour to pass through, leaving the coarse sand behind. Signup and view all the answers

Explain how decantation can be applied to separate a mixture of oil and water.

Decantation involves allowing the oil, which is less dense, to float on top of the water, and then carefully pouring the oil off without disturbing the water. Signup and view all the answers

Describe a situation where filtration would be the most suitable method of separation.

Filtration is suitable for separating sand from a mixture of water and sand, as it can effectively remove the solid particles while allowing the liquid to pass through. Signup and view all the answers

Why is decantation not effective for mixtures with fine silt and water?

Decantation is ineffective because fine silt remains suspended in water, preventing it from settling and being easily separated. Signup and view all the answers

What role does particle size play in the effectiveness of sieving?

Particle size determines whether a material can pass through the sieve; only those smaller than the sieve's holes can be separated effectively. Signup and view all the answers

How can the concepts of suspensions and solutions aid in choosing the right separation technique?

Recognizing whether a mixture is a suspension or a solution helps in selecting between filtration for suspensions and methods like evaporation for solutions. Signup and view all the answers

What are some limitations of using sieving for separation tasks?

Sieving cannot separate particles of similar sizes, and it is ineffective in separating very fine particles from liquids. Signup and view all the answers

What is the main difference between a suspension and a solution?

In a suspension, particles do not dissolve and can be seen, while in a solution, the particles are completely dissolved and not visible. Signup and view all the answers

How does filtration separate solid particles from liquids?

Filtration uses a barrier, like filter paper, to allow liquid to pass through while retaining solid particles. Signup and view all the answers

In the green mix experiment, what happened to the blue and yellow particles when water was added?

The blue particles dissolved in water, forming a solution, while the yellow particles remained insoluble, forming a residue. Signup and view all the answers

What role does filter paper play in the process of filtration?

Filter paper acts as a sieve that allows liquids to pass through while trapping larger, insoluble solid particles. Signup and view all the answers

Describe how sand and water can be separated using filtration.

A mixture of sand and water is poured through filter paper in a funnel, where sand is retained as residue and water is collected as filtrate. Signup and view all the answers

Explain the significance of sediment in a suspension.

Sediment forms when insoluble solid particles in a suspension settle at the bottom due to gravity, indicating that separation is possible. Signup and view all the answers

What is the outcome when water is added to a mixture of chalk and water?

Chalk particles form a suspension in water, as they are insoluble and can be filtered out from the liquid. Signup and view all the answers

Why are solids like sand and chalk classified as insoluble?

These solids do not dissolve in water, making it possible to separate them from a liquid through methods like filtration. Signup and view all the answers

How does a conical flask facilitate the collection of filtrate during filtration?

A conical flask's shape allows it to efficiently collect the liquid that passes through the filter paper in the funnel. Signup and view all the answers

What happens to the insoluble particles in a suspension when allowed to sit undisturbed?

Insoluble particles will eventually settle to the bottom, forming sediment if the suspension is left still. Signup and view all the answers

What is the main difference between a suspension and a solution?

A suspension contains larger solid particles that can settle over time, while a solution is a homogeneous mixture where the solute completely dissolves in the solvent. Signup and view all the answers

How does filtration work to separate mixtures?

Filtration separates solid particles from a liquid by passing the mixture through a filter paper that traps the solid while allowing the liquid to pass through. Signup and view all the answers

Name a common example of a suspension.

An example of a suspension is muddy water, where solid dirt particles are dispersed in water. Signup and view all the answers

What role does the solvent play in a solution?

The solvent is the liquid that dissolves the solute, forming a solution. Signup and view all the answers

Why can chalk and water be separated by filtration?

Chalk does not dissolve in water, resulting in a suspension that can be separated by using filter paper to capture the chalk particles. Signup and view all the answers

List two substances that are insoluble in water.

Sand and oil are examples of substances that are insoluble in water. Signup and view all the answers

What happens to a soluble substance when mixed with a solvent?

The soluble substance dissolves, forming a solution where it uniformly mixes with the solvent. Signup and view all the answers

Name a physical separation technique that can remove impurities from a liquid.

Filtration is a physical separation technique that can remove impurities from liquids. Signup and view all the answers

How can you separate a mixture of oil and water?

You can separate oil and water using a separating funnel because they are immiscible liquids and will layer based on density. Signup and view all the answers

What is the importance of understanding solubility in separation techniques?

Understanding solubility helps determine which separation technique to use, such as filtration for insoluble substances or evaporation for solutions. Signup and view all the answers

Study Notes

Separation Techniques

Sieving, Decanting, Magnets, Filtration, Evaporation (and crystallization), Distillation, and Chromatography are separation techniques.

Floatation

Plastic floats on water and can be scooped out with a net.

Separating Funnel

Separating funnels are used to separate two immiscible liquids of different densities.
The less dense liquid floats on top.
For example, oil floats on water.
You can separate oil and water by opening the tap and letting the water (the more dense liquid) out into a beaker.
Use a different beaker to collect the oil.

Centrifuge

A centrifuge is a machine that creates a rotational force, used to separate a mixture containing particles of different densities.
The centrifuge forces the more dense particles to the bottom of the tube, forming a pellet.
The remaining solution on top is called the supernatant.
The supernatant can be removed off the top with a pipette and placed into a new centrifuge tube.
The new tube can be spun at a faster speed to further separate the particles remaining in the mixture if they have different densities.

Centrifuging Blood

If you centrifuge blood, the red blood cells will form a pellet at the bottom of the tube.

Centrifuging Milk

Centrifuges can be used to separate cream from milk.
Before the invention of centrifuges, cream was skimmed off the top of milk after it had been sitting for a while.
Centrifuges make separating cream from milk faster and easier.

Separation Techniques

Sieving: Separates solids of different sizes
Decanting: Separates a liquid from a solid by pouring off the liquid carefully. Separating funnel
Magnets: Separates magnetic solids from non-magnetic materials.
Filtration: Separates an insoluble solid from a liquid using a filter paper.
Evaporation: Separates a soluble solid from a liquid by heating the liquid.
Crystallization: Recrystallized solid is separated from the liquid by heating the solution, evaporation, and cooling.
Distillation: Separates liquids with different boiling points.
Chromatography: Separates mixtures based on the different rates at which components move with the mobile phase.
Floatation: Separates solids based on their density, using a liquid where the solid floats.
Separating funnel: Separates two immiscible líquidos based on density. The less dense liquid forms a layer on top of the denser liquid.
Centrifuge: Spins a mixture at high speed, separating components based on their density. Denser particles form a pellet at the bottom, and the less dense liquid forms a supernatant layer.
Centrifuging applications: Separating blood plasma, cream from milk, and separating mixtures of different densities.

Separating funnel

Used to separate two immiscible liquids of different densities.
The less dense liquid floats on top.
Oil and water are immiscible, oil floats on water.
To separate, open the tap and let out the lower layer of water (more dense)
Then collect the oil (less dense).

Centrifuge

A machine that spins a mixture at high speed.
Used to separate a mixture containing particles of different densities.
Denser particles form a pellet at the bottom.
The remaining solution on top is called the supernatant.
In centrifugation, the supernatant can be spun at a faster speed to further separate the remaining particles if they have different densities.
Centrifuging blood: Separates blood components, including red blood cells, white blood cells, and platelets.
Centrifuging milk: Separates cream (fat) from milk.
Centrifuging mixtures: Separates different substances based on their densities.
The mixture is spun, and the largest particle forms a pellet first.
Each subsequent spin separates the next largest particle at the bottom.

Separating Funnel and Centrifuge Notes

1: Describe how to separate oil and water using a separating funnel. Draw a labelled diagram.
2: Explain how a centrifuge works to separate mixtures.
3: Describe what happens when freshly collected blood is put in a centrifuge and why this happens.
4: Describe what happens when freshly collected milk is put in a centrifuge and why this happens.
5: Draw a sketch of a centrifuge tube after a mixture has been centrifuged, label the pellet and the supernatant.

Separation Techniques

Sieving separates mixtures of different sized particles.
Decanting separates mixtures of a liquid and a solid where the solid settles at the bottom.
Magnets separate mixtures containing magnetic materials, like iron.
Filtration separates mixtures of solids and liquids, using filter paper.
Evaporation separates mixtures of a dissolved solid and a liquid, the liquid evaporates, leaving the solid behind.
Distillation separates liquids with different boiling points, the liquid with the lower boiling point evaporates first.
Chromatography separates mixtures based on the different rates at which substances move through a stationary phase.
Floatation separates mixtures based on the densities of the components.
Separating Funnel separates immiscible (non-mixing) liquids with different densities, it allows the denser liquid to be drained out.
Centrifugation separates mixtures based on the densities of the components.

Centrifuges

Centrifuges rotate at high speeds, causing denser particles to settle at the bottom, creating a pellet.
The liquid on top is called the supernatant.
Centrifugation can be used multiple times to separate particles with different densities.
Freshly collected blood in a centrifuge would separate into red blood cells (pellet), white blood cells and platelets (pellet), and plasma (supernatant).
Freshly collected milk in a centrifuge would separate into cream (less dense), and skimmed milk (more dense).
The supernatant from the first spin of a centrifuge can be spun again to further separate the particles remaining in the mixture.
In a centrifuge tube after a mixture has been centrifuged, the pellet is found at the bottom, and the supernatant is found on top.

Mixtures

Pure substances are difficult to break down, mixtures are easier.
Pure substances are elements and compounds
Mixtures are either homogenous or heterogenous

Homogenous Mixtures

Particles are spread evenly
Examples: nitrogen and oxygen in air, steel, vinegar, brass, black coffee, natural gas

Heterogenous Mixtures

Different components are scattered unevenly
Examples: salad, chocolate chip cookies, soda with ice.

Types of Mixtures (By particle size)

Solutions contain very small particles (less than 1000nm)
Colloids contain particles too small to settle or be removed by filtering
Suspensions contain larger particles that will settle or be removed by filtering

Solutions

Appear clear
Light beam will not be visible when shone through a solution

Colloids

Appear cloudy
Light beam will be visible when shone through a colloid
Examples: milk, mist, cappuccino froth, whipped cream, ice-cream, paint

Suspensions

Appear cloudy
Light beam will be visible when shone through a suspension
Examples: mud mixed with water

Types of Colloids

Foams - gas trapped within a liquid or solid (e.g. shaving cream)
Aerosols - liquid or solid particles dispersed in a gas (e.g. fog, smoke)
Emulsions - two or more insoluble liquids (e.g. homogenized milk, mayonnaise)
Gels - solid particles in a liquid medium (e.g. gelatin)
Sols - liquid particles in a solid medium (e.g. ink)

Emulsions

One liquid is able to spread evenly through another liquid instead of settling
Unhomogenized milk is not an emulsion, homogenized milk is
Emulsifiers keep immiscible liquids dispersed
Examples: mayonnaise, moisturizer, salad dressing

Immiscible Liquids

Do not mix
Water and oil are immiscible
Emulsifiers are chemicals added to immiscible liquids to keep them dispersed
Lecithin in egg yolk is the emulsifier in mayonnaise

The Tyndall Effect

The scattering of light by particles present in a colloid or suspension
The only difference between a colloid and a suspension is the size of the particles
Colloids have particles between 1-1000 nanometers
Suspensions have particles from 10-1000 micrometers

Chromatography

Stationary phase is the paper
Mobile phase is the water
Solvent front is the term used to describe how the solvent moves up the stationary phase
The baseline should be drawn with a pencil below the spots to avoid it dissolving in the solvent
Dyes that move a long way up the stationary phase have a high solubility in the solvent
Dyes that do not move very far up the stationary phase have a high affinity for the stationary phase
The solvent front is drawn at the point where the solvent has travelled furthest
Chromatograms for two different black ink pens will have different numbers and positions of spots because the dyes in the ink will be different
Rf value is calculated by the following formula : Rf=distancetravelledbysubstancedistancetravelledbysolventR_f = \frac{distance travelled by substance}{distance travelled by solvent}Rf=distancetravelledbysolventdistancetravelledbysubstance
The Rf values will change if a different solvent is used
Rf values for the spots X, Y and Z are:
- Rf X = 0.86
- Rf Y = 0.67
- Rf Z = 0.53

Decanting

Decanting is a technique to separate a dense, insoluble solid from a liquid.
The solid settles at the bottom of the container forming a sediment.
The liquid is carefully poured into a new container leaving the solid behind.
Decanting is only useful if the solid particles readily settle to the bottom.
It is commonly used when pouring some wines after the sediments have settled.

Sieving

Sieving separates a dry mixture of two solids with different particle sizes.
A sieve is chosen with holes that allow one particle through but not the other.
It is used to separate hazelnuts, peppercorns and sugar.
It is also used to separate pasta from the water it was boiled in.

Filtration

A special form of sieving that separates very fine solid particles from liquid or gas mixtures.
Filter paper with fine pores acts as the sieve.
It separates an insoluble solid from a liquid.
Sand does not dissolve in water and is considered insoluble.
When filtering sand and water, the sand (residue) stays behind in the filter paper, while the water (filtrate) passes through.
Filtration is used to separate insoluble particles that are too large to pass through the filter paper.

Suspensions

A mixture of very small pieces of solid mixed in a liquid but not dissolved.
The solid particles will separate from the liquid and either fall to the bottom or rise to the top.
Examples include sand in water and chalk in water.
The solid particles will sink to the bottom forming a sediment.
Suspensions can separate quickly or stay suspended for a longer time depending on their composition.

Solutions

When something dissolves, it is considered soluble.
The liquid that dissolves the solid is called the solvent.
The solid that dissolves is called the solute.
The new name for the liquid mixture with the dissolved solute is a solution.
Salt dissolves in water making a salt water solution.
Salt is the solute and water is the solvent.

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Description

Test your knowledge on various separation techniques used in science, such as filtration, distillation, and chromatography. This quiz covers methods for separating different substances effectively and their applications in real-life scenarios. Challenge yourself to understand the principles behind techniques like centrifugation and the use of separating funnels.