Heat as a Quantity 181 



QUESTIONS 



1. What will be the temperature of the liquid resulting from 

 the pouring of 2 pints of water at 200 F. into a gallon of water 

 at 65 F. ? 



2. How much water at 98 C. must be added to 5 kilograms 

 of water at 16 C. in order that the temperature of the resulting 

 mixture may be 63 C. ? 



3. Which is hotter a pound of water at 80 C. or 20 pounds of 

 mercury at 90 C., and which will cause the greater rise in the 

 temperature of a kilogram of water at 25 C., when mixed with the 

 latter ? 



4. 50 g. of magnesium (sp. heat, 0'245) at 15 C. are dropped 

 into 100 g. of water at 30 C. What is the highest temperature to 

 which the magnesium can be raised by this treatment ? 



5. Find the specific heat of lead from the following data : 



Weight of leaden shot used . . ... 200 g. 



Weight of water in calorimeter . . . . 100 g. 



Temperature of shot . . . . 100 C. 



Initial temperature of water . . . . 9*6 C. 



Final temperature of water . . . . 14*9 C. 



6. A flask containing a litre of mercury at 10 is placed in a 

 vessel of boiling water and allowed to remain till it has attained the 

 temperature of the water. How much heat is supplied to the mercury 

 by the water ? If the mercury be caused to give up the heat thus 

 received to a litre of water at 10, by how much will the temperature 

 of this volume of water be raised ? 



7. Pieces of platinum and aluminium foil of equal weight and 

 area are both rendered red-hot, and then allowed to cool. Why 

 may the platinum be handled with impunity with the fingers sooner 

 than the aluminium ? 



8. 500 g. of mercury at 100 C. are poured into a hole in a large 

 block of dry ice. How many grams of water will be formed during 

 the time taken by the temperature of the mercury to sink to C. ? 



9. 200 g. of ice are melted by dropping the ice into a vessel 

 containing 400 g. of water at 45 C. The temperature of the water 

 falls to 5 C. Find the water-equivalent of the vessel. 



