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Chemistry studying
chapter 17 prentice hall- heat
Question | Answer | Question | Answer |
---|---|---|---|
Endothermic | The system gains heat as the surroundings cool down (example: someone sitting my a campfire), defined as a positive q value | specific heat | specific heat of a substance is the amount of heat it takes to raise the temp of 1 gram of the substance 1 degree celsius. |
Exothermic | loses heat as the surroundings heat up. (Example: someone running and sweating), defined as a negative q-value because the system is losing heat | how to convert from joules to calories? | 1 joule= 0.239 cal and 4.184 J=1 calorie |
Heat | always flows from a warmer object to a cooler object. | heat capacity | depends on the mass and chemical composition of the object. it is defined as the amount of heat needed to raise the objects temp 1 deg celsius. |
Heat flow | measured in 2 common units: calories and the Joule. | q=?,m=?,c=?,deltaT=? | q=amount of heat, m=mass, c=specific heat of substance, deltaT= change in heat(final temp-initial temp) |
Calorie | defined as the quantity of heated needed to raise the temperature of 1 gram of pure water 1 degree Celsius. | device used to measure absobation or release of heat in an experiment | calorimeter |
C,c | C=dietary calorie (equals one kilocalorie/1000 calories). c=calorie | enthalpy | heat content of object at constant pressure AKA q (i think) |
10g of sugar has 41 calories | 10g of sugar releases 41 kilocalories of heat when completely burned | heat of fusion | h-delta-fus (the amount of heat absorbed by one mole of a solid substance as melts to a liquid) |
Equation to find amount of heat | Q=m•C•deltaT | heat of vaporization | amount of heat needed to vaporize 1 mole of a certain liquid |
Hess's law | determines the heat of reaction indirectly |