BASICS OF CALORIMETRY

heat energy – joules – SI unit temperature – kelvin, 0C – SI unit BASICS OF CALORIMETRY UNDERSTAND UNITS heat energy – joules – SI unit temperature – kelvin, 0C – SI unit mass -- kg – SI unit CONVERSION 1 calorie = 4.186 J (or) 4.2 J HEAT IS NOTHING BUT AN ENERGY HEAT FLOWS FROM A BODY OF HIGHER TEMPERATURE TO A BODY OF LOWER TEMPERATURE what is definition of calorie? Try to visualise it. 1 kg of water Heat energy required to raise 1 kg of water by 10C What does this mean? If I have 1 kg of water at 150C, I require 4200J of heat energy to raise it to 160C

FACTORS AFFECTING THE QUANTITY OF HEAT REQUIRED TO RAISE THE TEMPERATURE OF A BODY MASS -- IF THE MASS OF A SUBSTANCE IS MORE, I REQUIRE MORE HEAT TO RAISE ITS TEMPERATURE TO A GIVEN VALUE DIFFERENCE IN TEMPERATURE -- IF THE DIFFERENCE IN TEMPERATURE IS MORE (i.e) 20 DEGREES TO 80 DEGREES, I REQUIRE MORE HEAT WHEREAS IF THE DIFFERENCE IS LESS (i.e) 30 DEGREES TO FIFTY DEGREES, I REQUIRE LESS HEAT. DEPENDS ON THE MATERIAL -- IF THE LIQUID IS WATER, MORE HEAT IS REQUIRED, IF THE MATERIAL IS OIL, LESS HEAT IS REQUIRED

HEAT CAPACITY OR THERMAL CAPACITY THEREFORE H = mC T THEN WHAT IS THE UNIT?? H – JOULES/CALORIES m – g (or) kg DIFFERENCE IN TEMPERATURE = DEGREES C (OR K) THEN WHAT IS THE UNIT OF SPECIFIC HEAT CAPACITY? C = H = JOULES = Jg -1 0C-1 (or) J g -1 K-1 m T Gk HEAT CAPACITY OR THERMAL CAPACITY IT IS THE HEAT REQUIRED TO RAISE A GIVEN MASS OF A SUBSTANCE BY ONE DEGREE CENTIGRADE

SPECIFIC HEAT CAPACITY IT IS THE HEAT REQUIRED TO RAISE UNIT MASS OF A SUBSTANCE THROUGH ONE DEGREES CELSIUS. LEAD HAS A SPECIFIC HEAT CAPACITY OF 130 Jk g -1 K-1WHAT DOES IT MEAN? IF I HAVE 1 KILOGRAM OF LEAD AT (SAY) 100C, I REQUIRE 130 JOULES OF HEAT ENERGY TO RAISE IT TO 110C. (OR) IF I HAVE 1 KILOGRAM OF LEAD AT (SAY) 120C, I SHOULD REMOVE 130 JOULES OF HEAT ENERGY TO LOWER IT TO 110C. WHY IS COPPER USED AS A CALORIMETER? HOW DOES THE HEAT TRANSFER IN A CALORIMETER IS PREVENTED?