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What is an atom?
This is the smallest part of an element
What is a molecule?
This is when two atoms are joined together by chemical bonds eg. carbon dioxide
What is a mixture?
A mixture is two or more substances that are mixed together but are not joined by chemical bonds eg. air
What is an element?
An element is a substance that has only one type of atom eg. copper
What is a compound?
A compound is made up of two or more different elements joined together by chemical bonds eg. water
List the differences between a compund and a mixture
A compound is hard to change back but a mixture is easy to change back
A coumpond is held together by chemical bonds but a mixture is not
What are impurities?
These can be added to water in order to influence its physical properties
For example, adding salt to water lowers its freezing point, causing ice to melt
What is a solution?
This is when a solute dissolves in a solvent
What is a solute?
This is the substance that dissolves eg. sugar
What is a solvent?
This is the substance the solute dissolves in eg. water
What is meant by soluble?
This is when a solid dissolves into a substance
What is meant by insoluble?
This is when a solid does not dissolve into a substance
What is suspension?
This happens when a solid does not dissolve and instead it may settle to the bottom of the liquid or end up floating throughout the liquid, making it cloudy
What is meant by solubility?
This is a measure of how much solute can dissolve in a fixed volume of solvent to make a saturated solution
In a solution solids become more soluble in the solvent as the temperature increases
In a solution gases become less soluble in the solvent as the temperature increases
State the factors that affect the solubility of a substance
1. The nature of the substance ie. soluble or insoluble
2. The volume of the solvent
3. The temperature of the solvent
What is meant by concentration?
This is used to describe how much solute is dissolved in a solvent
What is a dilute solution?
This contains a small amount of solute in a large amount of solvent
What is a concentrated solution?
This contains a large amount of solute in a small amount of solvent
What is a saturated solution?
This is a solution that contains as much solute as possible at a given temperature
What is crystallisation?
This is the formation of crystals when a hot saturated solution is cooled
List the different methods to separate mixtures?
6. Separating Immiscible Liquids
What is filtration?
This is used to separate insoluble solids from liquids eg. sand and water
What is chromatography?
This is used to separate mixtures of substances that are in solution eg. inks in a marker
What is evaporation?
This is used to separate a liquid and a soluble solid eg. salt and water
What is distillation?
This is used to separate a liquid and a soluble solid when you want to keep the liquid or when separating two liquids that do not mix
For example salt and water or alcohol and water
What is fractional distillation?
This is used to separate crude oil
What is fracking?
This involves drilling down into the earth and injecting a mixture of water, sand and chemicals into the rock at high pressure, which releases the gas trapped inside the rock