Calorimetry Short Answer

SHORT ANSWER 1. Is heat a conserved quantity? [Sol. No, it can be converted to heat and work.] 2. The calorie is defined as 1 cal = 4.186 joule. Why not as 1 cal = 4 J to make the conversions easy? [Sol. 4.186 Joule of work has to be done on water to raise its temperature by 1° which is 1 cal. So 4.186 J = 1 cal.] 3. A calorimeter is kept in a wooden box to insulate it thermally from the surroundings. Why is it necessary? [Sol. If not done then heat will be lost to the surrounding, for which we will have no account. Our experimental procedure was to exchange heat between masses only.] 4. In a calorimeter, the heat given by the hot object is assumed to be equal to the heat taken by the cold object. Does it mean that heat of the two objects taken together remains constant? [Sol. Meaningless question. A body doesn’t possess heat. Heat is not an intrinsic property of system. When the energy is in the flowing stage and getting transferred due to temperature difference it is called heat. When energy reaches in the body it is called internal energy.] 5. In Regnault's apparatus for measuring specific heat capacity of a solid, there is an inlet and an outlet in the steam chamber. The inlet is near the top and the outlet is near the bottom. Why is it better than the opposite choice where the inlet is near the bottom and the outlet is near the top? [Sol. Steam enters and leaves as liquid so outlet must be in bottom as liquid cannot come from top.] 6. When a solid melts or a liquid boils, the temperature does not increase even when heat is supplied. Where does the energy go? [Hint: latent heat.] 7. What is the specific heat capacity of (a) melting ice (b) boiling water? [Sol. both are not defined as heat given does not raise the temperature but it goes in converting phase.]

8. A person's skin is more severely burnt when put in contact with 1 g of steam at 100°C than when put in contact with 1 g of water at 100°C. Explain. [Sol. There is latent heat involved with steam and not with boiling water.] 9. The atmospheric temperature in the cities on sea-coast change very little. Explain. [Sol. Because of convection current heat exchange (transfer) takes place between land and sea.] 10. Should a thermometer bulb have large heat capacity or small heat capacity? [Sol. It must have large heat capacity as Q = ms T Q T = ms While measuring temperature it will given heat and specific heat is high rise in temperature will be low and expansion will be low which is required.]