Heat capacity Gen Chem

Question

Two solid objects, A and B, are place in boiling water and allowed to have the same temperature there. Each object is then lifted out and placed in separate beakers containing 1000 g of water at 10.0 C. Object A increases the water temperature by 3.60 C and B increases the water temperature by 2.75 C. Which object has the larger heat capacity?

Answer 1

Heat capacity can essentially be defined as the amount of heat required to raise the temperature of 1 gram of substance by 1 degree.

First, we must assume that both object A and B have the same mass (not stated in the problem). Then, since object A increased the temperature of water by more than did object B, this tells us that it contained more heat per gram. Thus, we conclude that object A had a greater heat capacity.

To look at this numerically, we will calculate the heat capacity of both A and B, assuming 1 g of each, as follows :

Heat gained by water must = heat lost by object A or B

q = mC∆T

q = heat = ?

m = mass of water = 1000 g

C = specific heat of water = 4.184 J/gº

∆T = change in temperature of water = 3.60º for A and 2.75º for B

Heat lost by A:

q = (1000 g)(4.184 J/gº)(3.60º) = 15062 J/gº = heat capacity of A

Heat lost by B:

q = (1000 g)(4.184 J/gº)(2.75º) = 11506 J/gº = heat capacity of B