Science Chapter: Mixtures and Pure Substances
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Questions and Answers

Which of the following mixtures can be separated using a combination of filtration and evaporation?

  • Wheat and chaff
  • Alcohol and Water
  • Iron filings and sand
  • CaCO3 and NaCl (correct)

    • Which of the following is a characteristic of a suspension?

  • The solute particles are dissolved.
  • It is a homogeneous mixture.
  • The particles are visible to the naked eye. (correct)
  • The components cannot be separated by filtration.

    • Fractional distillation is used to separate miscible liquids based on differences in their melting points.

    False (B)

    An emulsion is a type of homogeneous mixture.

    <p>False (B)</p> Signup and view all the answers

    What is the principle behind froth floatation?

    <p>differential wetting of components by water</p> Signup and view all the answers

    In fractional distillation, a _________ is used to measure the temperature of the vapors.

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

    Name a method that can be used to separate the components of a suspension.

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

    A mixture of oil and water is an example of a(n) _______.

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

    Which of these is not an example of a mixture that can be separated by physical means mentioned in the text?

    <p>Iron and sulfur (C)</p> Signup and view all the answers

    Match the following separation techniques with their primary application:

    <p>Magnetic Separation = Separating iron from other substances Sieving = Separating grains from mixtures based on size Fractional Distillation = Separating miscible liquids with different boiling points Froth Floatation = Separating metal ores from impurities</p> Signup and view all the answers

    Which of the following is NOT considered a suspension?

    <p>Salt in water (C)</p> Signup and view all the answers

    Sublimation is used to separate salt from sand.

    <p>False (B)</p> Signup and view all the answers

    Alloys are formed by physically mixing metals together at room temperature.

    <p>False (B)</p> Signup and view all the answers

    Match the following mixtures with their type:

    <p>Sand in water = Suspension Oil in water = Emulsion Salt in water = Solution Shaving cream = Emulsion</p> Signup and view all the answers

    How can grain be separated from a mixture of grain, salt and sand?

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

    A solution is a _______ mixture of two or more substances.

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

    Which of these separation methods relies on the principle of the difference in boiling points?

    <p>Distillation (C)</p> Signup and view all the answers

    In froth floatation, the impurities float to the surface with the desired mineral.

    <p>False (B)</p> Signup and view all the answers

    What is the primary use of centrifugation?

    <p>To separate components of a mixture based on density.</p> Signup and view all the answers

    In the process of distillation, the component with the ______ boiling point evaporates first.

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

    Match the following separation techniques with their correct description:

    <p>Sublimation = Separates substances that turn directly from solid to gas Froth floatation = Separates mixtures using a froth to carry lighter particles Distillation = Separates liquids with different boiling points Centrifugation = Separates components based on density using a spinning motion</p> Signup and view all the answers

    Which mixture can be separated by sublimation?

    <p>Ammonium chloride and salt (A)</p> Signup and view all the answers

    In evaporation the liquid component is recovered while in distillation liquid component is lost to the atmosphere.

    <p>False (B)</p> Signup and view all the answers

    What is the purpose of the condenser in distillation apparatus?

    <p>To cool the vapor into liquid.</p> Signup and view all the answers

    Study Notes

    Centrifugation

    • A centrifuge is used to separate suspended particles from a mixture.
    • A model centrifuge is shown in a figure.

    Elements, Compounds, and Pure Substances

    • A pure substance can be an element or a compound.
    • Pure substances have a fixed composition and chemical properties.
    • Examples include elements like copper and aluminum, and compounds like salt and sugar.
    • Elements and compounds are pure substances.

    Mixtures

    • A mixture is made up of two or more pure substances.
    • Components retain their individual properties.
    • Components are not chemically combined.
    • Examples include lemon juice (lemon extract, sugar, water), and air (various gases).
    • Mixtures can be homogeneous or heterogeneous.

    Homogeneous Mixtures

    • Components cannot be differentiated by color, shape or size.
    • Evenly distributed.
    • Appear as a single entity.
    • Examples include salt solution, and alloys.

    Heterogeneous Mixtures

    • Non-uniform composition.
    • Composition varies from one region to another
    • Examples include chalk in water, sand, and rice.

    Suspensions

    • A heterogeneous mixture with solid particles of a sufficient size for sedimentation.
    • Components can be separated by filtration.

    Emulsions

    • A mixture of immiscible liquids.
    • Particles of one liquid are suspended throughout the other.
    • Examples include mixtures of oil and water.

    Separation Techniques

    • Several techniques can be used to separate components of mixtures.
    • Techniques depend on the properties of the components and the type of mixture.

    Filtration

    • Separating an insoluble solid from a liquid.
    • Mixture is passed through a filter paper.
    • Insoluble solid is trapped on the filter paper (residue).
    • Liquid passes through the filter paper (filtrate).

    Evaporation

    • Separating a soluble solid from a liquid.
    • Liquid is heated.
    • Water evaporates, leaving the solid behind.

    Distillation

    • Separating liquids from a mixture based on their different boiling points.
    • Liquid with a lower boiling point vaporizes first.
    • Vapors are cooled and condensed into a separate container.

    Fractional Distillation

    • Separating miscible liquids with similar boiling points.
    • Uses a fractioning column to improve separation efficiency.

    Sublimation

    • Separating a solid that changes directly to a gas (sublimes) from a solid mixture.
    • The solid is heated.
    • Solid turns into gas and is collected elsewhere.

    Magnetic Separation

    • Separating magnetic materials from a non-magnetic mixture.

    Froth Floatation

    • Separating a metal ore from gangue (undesirable materials) by differential wetting.
    • The ore is mixed with water.
    • Chemical reagents are added to make the ore wettable
    • The ore is separated and collected in a separate form.

    Sieving

    • Separating materials of different sizes.
    • The mixture is poured through a sieve with holes of a specific size.
    • The larger particles are collected on top.

    Alloys

    • Homogeneous mixtures of two or more metals.
    • Obtained by melting metals together.

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    Elements, Compounds and Mixtures PDF

    Description

    Explore the concepts of mixtures, elements, compounds, and pure substances in this engaging quiz. Understand the differences between homogeneous and heterogeneous mixtures through examples from the real world. Test your knowledge and enhance your understanding of these fundamental scientific ideas.

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