P6 - Molecules and Matter

P6 - Molecules and Matter...

This is the density equation, I rember it by: Milkshake over Dominoes (pizza) is Vile!

• It is measured in kg/m^3

• Objects that have a lower density than water ( 1000kg/m^3) float.

• Check out the required practical for this!

• solids - least energetic
• liquids - more energetic than solids
• Gas - most energetic
• When a substances changed state, its mass stays the same as it has the same number of particles. 

• For a pure substance - it's melting point is the temperature when it melts. 
• Boiling point is temperature when it boilds. 
• Energy is needed to melt or boil a liquid. 

• Boiling occours in a liquid at it's boiling point. 
• Evaporation occours in a liquid on the surface when it's temperature is below it's boiling point.

• Increasing temperature of substance increases internal energy. 

• Solid: 
• Strong forces of attraction 
• when heated, the energy stores in the particle and they vibrate more. 

• Liquid:
• Weaker forces of attration.
• When heated, some particles gain enough energy to break away and turn into a gas state.
• Gas:
• No forces of attraction.
• When heated, particles gain kinetic energy and move faster.  

• Specific latent heat of fusion Is the energy needed to change 1kg of substance from solid to liquid with no temperature change. 

• Specific latent heat of fusion/ vapourisation (J/kg) = Energy (J) / mass (kg)

• Simple latent heat of vaporisation is the energy needed to change 1kg of substance from liquid to vapour, with no temperature change.

• The specific latent heat of ice or water can be measured using using a low voltage heater to melt the ice or boil the water.

• Pressure of gas is caused by the random impacts of gas molecules on surfaces. 

• If the temperature of a gas increases in a sealed container the pressure increases as: 
• the molecules hit the surfaces with more force as they are moving fast. 
• the no. of impacts per second of gas molecules hitting the container increase. 

• The unpredictable motion of smoke particles in air is evidence of random motion of gas.