Question

Name Find the total change in energy for these situations: a) A gas releases 53.23 of heat and does 23.7 of work on its surroundings b) A gas absorbs 15.7 of heat and has 42:3 N of work done to i ts Q5. A chemist conducts a calorimetry experiment on an unknown metal. The mass of the sample is 244The chemist heats the metal to 100 "C. then places it in a coffee cup calorimeter containing 108.5 of water. The temperature of the water rises from 21.3 to 25.0 "C. a) How much heat was absorbed by the water? (3pts) b) How much heat was released by the metal? (3pts) c) What is the specific heat of the metal? (4pts)

Answer 1

4)

a)

Q = -53.2 KJ

Negative because system is releasing heat

W = -23.7 KJ

Negative because system is doing work.

Use:

Delta E = Q + W

= -53.2 KJ - 23.7 KJ

= -76.9 KJ

Answer: -76.9 KJ

b)

Q = 15.7 KJ

Positive because system is absorbing heat.

W = 42.3 KJ

Positive because work is done on the system.

Use:

Delta E = Q + W

= 15.7 KJ + 42.3 KJ

= 58.0 KJ

Answer: 58.0 KJ

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