Q. Value for the specific latent heat of fusion of water:
Specific latent heat is where the amount of energy (in joules) needed to change the state of 1Kg of a substance is called its specific latent of heat.
You can calculate the amount of energy needed using the equation: energy (J) = specific latent heat (J/Kg) X mass (Kg)
Material Specific heat of fusion (J/Kg) Specific latent heat of vaporisation (J/Kg)
Water 334000 2260000
Lead 24500 871000
Ethanol 108000 855000 (OCR gateway GCSE science- page 170)
2. RESEARCH -Specific heat capacity:
The amount of energy in joules, needed to raise the temperature of 1kg of material by 1c.
Material Specific heat capacity (J/KgC)
Water 4200
Calculating the amount of heat transferred:
Energy (J) = mass (Kg) X specific heat capacity (J/KgC) X temperature change (C)
(OCR gateway GCSE science- page 169)
3. Why energy is needed to melt ice and how this is explained by the structures of ice and water?
At point of A, energy has been added to the water and the temperature of the water is rising because the of the increase in energy.
At point B the energy has moved on from raising the temperature to braking down the intermolecular bonds of the ice. The temperature has stopped rising while the bonds are being broken.
At point C all the bonds had been broken down and the energy had gone into rising the temperature again until it reaches 100C.
At point D the water had risen to 100C and now the energy has gone into breaking the bone to cause evaporation. When the bonds have been all broken the energy goes back into rising the temperature, and that is what E is. http://www.physchem.co.za/Heat/Latent.htm or http://www.kentchemistry.com/links/Energy/HeatFusion.htm
Q- Why ice is more effective for cooling a drink than cold water?
The cooling of a drink with a cube of ice is more effective than using cold water because of the energy extracted from the drink to melt