States of matter

What are the 3 states of matter?

Solids

Liquids

Gases

What are the properties of solids?

Arrangement: Particles are close together & regularly arranged

Movement: Particles vibrate around a fixed position

Energy: Lowest KE

What are the properties of liquids?

Arrangement: Particles are close together & irregularly arranged

Movement: Particles move freely

Energy: KE greater than solids but lower than gases

What are the properties of gases?

Arrangement: Particles are far apart & irregularly arranged

Movement: Particles move freely & randomly

Energy: Greatest KE

Solid → liquid

Melting

Liquid → solid

Freezing

Liquid → gas

Boiling / evaporation

Gas → liquid

Condensation

Solid → gas

Sublimation

Gas → solid

Deposition

Why does heating a liquid cause it to evaporate faster?

Because when a liquid is heated it gains more KE

This means that the particles in the liquid can overcome the forces of attraction holding them together, making it easier for them to evaporate into a gas

What term is used to describe the energy change between gases & liquids?

Exothermic

This is because heat energy is released

A solvent is…

a substance in which a solute can dissolve in

A solute is…

a substance that can be dissolved to form a solution

A solution is…

a mixture formed when a solute dissolves in a solvent

Dilution is…

When more solvent is added to a solution, causing the particles to spread further apart

What is a saturated solution?

A solution that contains the maximum concentration of solute so that no more of it can be dissolved into the solution

What is solubility?

The maximum mass of a solute that can be dissolved in 100g of solvent

(grams of solute per 100 grams of solvent)

The solubility of solids increases when…

The temperature increases

The solubility of gases increases when…

The pressure increases

What is a solubility curve?

A graph showing the solubility of a substance against temperature

Any mass below the line for a solute at a specific temperature means that…

The solution is unsaturated

Any mass above the line for a solute at a specific temperature means that…

The solution is saturated & unstable

Why does diffusion not occur in solids?

Because diffusion requires particles that are free to move & the particles in solids are not free to move as they only vibrate in fixed positions

Explain a method to investigate the solubility of a solid in water at a specific temperature

1 At a specific temperature (e.g. 40⁰C) a saturated solution (e.g. KNO₃) is created

2 Some of this solution is poured off & weighed & then heated using a Bunsen burner

3 Water from the solution evaporates, leaving behind a residue of solute which is then weighed

4 Mass of evaporated water = mass of saturated solution - mass of solute

5 Solubility = mass of solute ÷ mass of solvent × 100

What happens when ammonium chloride (NH₄Cl) is heated in a test tube?

- A mixture of 2 gases form (NH₃ & HCl)

- A white solid forms (NH₄Cl)

- Decomposition & neutralisation occur