Question

A student has calibrated his/her calorimeter and finds the heat capacity to be 14.2 J/°C. S/he then determines the molar heat capacity of aluminum. The data are: 25.5 g Al at 100.0°C are put into the calorimeter, which contains 99.0 g H2O at 18.6°C. The final temperature comes to 22.7°C. Calculate the heat capacity of Al in J/mol·°C.

Answer 1

The heat capacity of Al is 24,01 J/mol·°C

Step-by-step explanation:

The energy absorbed by the calorimeter is:

14,2 J/°C×(22,7°C-18,6°C) = 58,22 J

This energy is equivalent to energy libered by aluminium minus energy absorbed by water:

58,22J = HcAl×25,5g×(100°C-22,7°C) - 4,18J/molK×99,0g×(22,7°C-18,6°C)

Where HcAl is Heat capacity of aluminium in J/g°C

58,22J = HcAl×1971,15 - 1696,7 J

1754,9J/1971,15g°C = HcAl

HcAl = 0,89 J/g°C

This heat capacity in J/mol°C is:

0,89 J/g°C×(26,98g/1mol) = 24,01 J/mol°C

I hope it helps!