1- The molar mass and molar heat capacity of aluminum is 27.0 g/mol and 24.3 J/(
ID: 550893 • Letter: 1
Question
1- The molar mass and molar heat capacity of aluminum is 27.0 g/mol and 24.3 J/(mol K), respectively. If a 27.0-g Al sample, at 300. K, absorbed 168 J of heat, what is its final temperature?
2- The molar mass and molar heat capacity of aluminum is 27.0 g/mol and 24.3 J/(mol K), respectively. If a 27.0-g Al sample, at 300. K, absorbed 152 J of heat, what is its final temperature?
3- 100. g water, at 20 C, and 100. g copper, at 80 C, are mixed in an insulated calorimeter. Without doing any calculation, predict a reasonable final temperature after thermal equilibrium is reached. Select the best option!
1- 50 C
2- 60 C
3- 100C
4-30 C
Explanation / Answer
1)
mol of Al, n = mass / molar mass
= 27.0 g. /27.0 g/mol
= 1 mol
C = 24.3 J/mol.K
use:
Q = n*C*(Tf-Ti)
168 = 1*24.3*(Tf - 300)
Tf - 300 = 6.9
Tf = 307 K
Answer: 307 K
2)
mol of Al, n = mass / molar mass
= 27.0 g. /27.0 g/mol
= 1 mol
C = 24.3 J/mol.K
use:
Q = n*C*(Tf-Ti)
152 = 1*24.3*(Tf - 300)
Tf - 300 = 6.3
Tf = 306 K
Answer: 306 K
3)
since heat capacity of water is greater than that of copper, final temperature will be closer to initial temperature of water
Answer: 30 C
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