Answer to Question #97808 in General Chemistry for Brittany Wallace

Question

In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat of a solid, or to measure the energy of a solution phase reaction.

Since the cup itself can absorb energy, a separate experiment is needed to determine the heat capacity of the calorimeter. This is known as calibrating the calorimeter and the value determined is called the calorimeter constant.

One way to do this is to use a common metal of known heat capacity. In the laboratory a student heats 94.80 grams of nickel to 98.66

Answer 1

$m_{nickel}=94.80g$

$C_{nickel} = 0.440J/(g.°C)$

$T_{nickel}=98.66°C$

$T_{equilibrium}=32.16°C$

$Q_{nickel}=m_{nickel}×C_{nickel}×(T_{equilibrium}-T_{nickel})$

$Q_{nickel}=94.80×0.440×(32.16-98.66)$

$Q_{nickel}=94.80×0.440×(-66.50)$

$Q_{nickel}=-2773.848J$ (released)

$m_{water}=84.19g$

$C_{water}=4.186J/(g.°C)$

$T_{water}=24.25°C$

$Q_{water}=m_{water}×C_{water}×(T_{equilibrium}-T_{water})$

$Q_{water}=((84.19)×(4.186)×(32.16-24.25))J$

$Q_{water}=((84.19)×(4.186)×(7.91))J$

$Q_{water}=2787.637J$ (absorbed)

$Q_{calorimeter}=-13.789J$

$Calorimeter Constant =Q_{Calorimeter}/(T_{equilibrium}-T_{water})$

$Calorimeter constant=-13.789/7.91=-1.743J/°C$

(Answer)

Calorimeter constant is negative which is not possible.Actually in this question,heat released by nickel is less than heat absorbed by water which is an impossible case.So, the information given in the question are not properly adjusted.