AIM How do we solve problems related to heat when there is no change in temperature? DO NOW – How much heat does it take to raise a 100g sample of water 10 degrees?

Why phase changes Heating a substance causes the temperature to increase Heating causes particles to move faster and collide harder Moves them further apart Larger distances equals weakening the forces of attraction between them When the forces of attraction are weak enough, the distance between the particles increases markedly and the phase changes

Phase Change During a phase change the substance is gaining energy, but not gaining temperature So at 0oC H2O(s) is given 1000J of heat and turns into 0oC H2O(l)

What it is called Adding Heat Solid ----> Liquid ________ Liquid ----> Gas The reverse happens when a substance cools Gas ----> Liquid Liquid ----> Solid Some odd ones between solid and gas Solid ----> Gas Gas ----> Solid

Graphic Organizer

Heat of Fusion Hf=The amount of heat needed to a solid into a liquid For water the Hf=334 J/g Q=(m)(Hf) So how much heat does it take to change 200g of water from a solid to a liquid?

Answer So how much heat? Q=(m)(Hf) Q=(200g)(334J/g) Q=66,800J

Heat of Vaporization Hv=The amount of heat needed to change a liquid into a gas For water the Hv=2260 J/g Q=(m)(Hv) So how much heat does it take to change 200g of water from a liquid to a gas?

AIM How to solve all heat problems? DO NOW- How much heat does it take to change 150g of ice into water?

Answer Q= (m)(Hv) Q= (200g)(2260 J/g) Q= 452,000 J

Example Lets look at the example of one of the hand outs This is called a heating/cooling curve Specific heat capacity water 4.187 J/goC Specific heat capacity ice 2.108 J/goC Specific heat capacity water vapor 1.996 J/goC Hv=2260 J/g Hf=334 J/g