Mixtures, Solutions, and Pure Substances

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Questions and Answers

What distinguishes a pure substance from a mixture?

Pure substances can be separated by physical means.

A pure substance contains identical particles. (correct)

Mixtures contain only one type of particle.

Pure substances are always liquids.

Which of the following is an example of a colloid?

Hot chocolate (correct)

Muddy water

Oil and vinegar

Saltwater

What role does an emulsifier play in a mixture?

It helps substances mix together. (correct)

It thickens the liquid.

It separates solids from liquids.

It makes substances more soluble.

Which of the following solutions is considered concentrated?

200ml of water with a tablespoon of sugar Signup and view all the answers

What characterizes a suspension?

Solid particles are spread throughout a liquid. Signup and view all the answers

What is a key feature of insoluble substances?

They do not dissolve and remain visible. Signup and view all the answers

How would you characterize a solution where a smaller amount of solute has been added?

Dilute Signup and view all the answers

Which method would best separate iron fillings from a mixture of iron fillings and sand?

Magnetic separation Signup and view all the answers

What is the primary purpose of a flocculant like aluminium sulfate in a colloid?

To make suspended particles clump together and sink Signup and view all the answers

During the process of filtration, what is left behind on the filter paper?

Residue Signup and view all the answers

What occurs during the process of distillation?

Liquid is boiled and transformed into gas, then condensed back to liquid Signup and view all the answers

What is the result of the evaporation process?

The transformation of a liquid into gas, leaving solids behind Signup and view all the answers

What does centrifuging achieve in a mixture?

It spins the mixture to separate components based on mass Signup and view all the answers

What is the main difference between filtrate and distillate?

Filtrate comes from filtration and distillate comes from distillation Signup and view all the answers

Which statement best describes flotation?

It involves particles floating on top of a solution due to density differences. Signup and view all the answers

What is the role of filter paper in filtration?

To trap solid residues while allowing liquids to pass through Signup and view all the answers

Study Notes

Mixtures

A mixture is a combination of two or more substances in any proportion.
Lemonade is an example of a mixture, containing water, lemon juice, and sugar.

Pure Substances

A pure substance contains only one type of particle.
Sugar is a pure substance because it is made up of only sugar particles.

Solutions

A solution is a mixture where one substance is dissolved evenly throughout another.
Cordial is a solution because the cordial particles are dissolved evenly through the water.

Suspensions

A suspension is a mixture where a solid is spread throughout a liquid.
Muddy water is a suspension because the dirt particles are spread evenly throughout the water.
The solid particles in a suspension can settle to the bottom and form a sediment.

Colloids

A colloid is a mixture where particles are too small to settle or be removed by filtering.
Hot chocolate is a colloid because the hot chocolate powder particles are too small to sink to the bottom.

Emulsions

An emulsion is a type of colloid where the particles of one liquid are spread evenly throughout another liquid.
Milk is an emulsion because the fat particles are suspended in another liquid.

Emulsifiers

An emulsifier is a chemical that changes the properties of a substance to help them combine with each other.
Eggs are emulsifiers. When mixed with oil and water, they change the properties of the oil and water so they can mix together.

Soluble and Insoluble Substances

Soluble substances dissolve in a liquid.
Sugar is soluble because it dissolves in water and you can no longer see the sugar particles.
Insoluble substances do not dissolve in a liquid.
Dirt is insoluble because it does not dissolve in water and you can still see the dirt particles.

Solutes and Solvents

The solute is the substance that is being dissolved into a solvent.
In sugary water, the solute is sugar and the solvent is water.

Concentrated and Dilute Solutions

A concentrated solution has a high amount of solute dissolved in the solvent.
A tablespoon of sugar dissolved in 200ml of water is a concentrated solution.
A dilute solution has a small amount of solute dissolved in the solvent.
A pinch of sugar dissolved in 200ml of water is a dilute solution.

Separation Techniques

Magnetic Separation

Used to separate magnetic materials from non-magnetic materials.
For example, iron fillings can be separated from sand using a magnet.

Decanting

Carefully pouring off a liquid, leaving behind a solid that has settled to the bottom.
For example, you can decant water from a beaker of rocks and water.

Flotation

Separation based on the density of the components.
Less dense components will float on top of a more dense liquid.
For example, foam floats on top of water because it has a lower density than water.

Flocculation

Using a flocculant chemical to clump together suspended particles, causing them to sink to the bottom.
Aluminum sulfate is a flocculant. When added to a colloid, it causes the particles to sink to the bottom.

Filtering

Separating a mixture by pouring it through a filter paper.
The liquid that passes through the filter paper is called the filtrate.
The solid particles that remain on the filter paper are called the residue.
For example, you can filter water from a mixture of water and chalk.

Centrifuging

Spinning a mixture very quickly to separate components based on their mass or density.
Heavier components will settle to the bottom of the centrifuge tube, while lighter components will stay at the top.
For example, spinning blood in a centrifuge will separate the red blood cells (which are heavier) from the plasma (lighter).

Evaporation

The process of changing a liquid into a gas.
This can be used to separate a dissolved solid from a liquid.
For example, evaporating salt water will leave behind salt crystals.

Crystallisation

The process of evaporating the solvent from a solution, leaving behind crystals of the solute.
For example, evaporating salt water will result in crystallisation of the salt.

Distillation

Separating a mixture by boiling it and then condensing the vapor.
The substance with the lower boiling point will evaporate first and be collected as the distillate.
For example, boiling wine will separate the alcohol (which has a lower boiling point) from the other components.
The liquid that is collected after condensation is called the distillate.

Condensation

The process of changing a gas into a liquid.
This occurs during distillation.
The vaporized liquid cools and condenses back into a liquid in the condenser.

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Description

This quiz covers the concepts of mixtures, pure substances, solutions, suspensions, and colloids. Explore different types of mixtures with examples like lemonade and muddy water. Test your understanding of these fundamental chemistry concepts.