Name: __________________________
Date: ____________
Physics I C
Mr. Tiesler
Thermodynamics Practice Problems
1.) A certain mass of water was heated with 41,840 Joules, raising its temperature from 22.0 °C
to 28.5 °C. Find the mass of the water, in grams. (c of H2O = 4.18 J/g °C)
𝑄 = 41,840 𝐽
∆𝑇 = 28.5 ℃ − 22.0 ℃ = 6.5 ℃
𝑐 = 4.18 𝐽⁄𝑔 ∙ ℃
𝑄 = 𝑚𝑐∆𝑇
𝑚=
𝑄
41,840 𝐽
=
= 1,540 𝑔
𝑐∆𝑇 (4.18 𝐽⁄𝑔 ∙ ℃)(6.5 ℃)
2.) What is the specific heat capacity of silver metal if 55.0 g of the metal absorbs 47.3 calories
of heat and the temperature rises 15.0°C? (1 cal = 4.186 J)
𝑚 = 55.0 𝑔
4.186 𝐽
𝑄 = 47.3 𝑐𝑎𝑙 (
) = 198 𝐽
1 𝑐𝑎𝑙
∆𝑇 = 15.0 ℃
𝑐 =?
𝑄 = 𝑚𝑐∆𝑇
𝑐=
𝑄
198 𝐽
=
= 0.240 𝐽⁄𝑔 ∙ ℃
𝑚∆𝑇 (55.0 𝑔)(15.0 ℃)
3.) A 7.5 kg bar of copper at 25.0 oC absorbs 3.5x104 J of heat. What is the final temperature of
the copper?
𝑚 = 7.5 𝑘𝑔
𝑇𝑖 = 25.0 ℃
𝑐 = 390 𝐽⁄𝑘𝑔 ∙ ℃
𝑇𝑓 =?
𝑄 = 3.5𝑥104 𝐽
𝑄 = 𝑚𝑐∆𝑇
𝑇𝑓 =
𝑄
3.5𝑥104 𝐽
+ 𝑇𝑖 =
+ 25.0 ℃ = 37.0 ℃
(7.5 𝑘𝑔)(390 𝐽⁄𝑘𝑔 ∙ ℃)
𝑚𝑐
Name: __________________________
Date: ____________
Physics I C
Mr. Tiesler
Thermodynamics Practice Problems
4.) How much heat energy is given out when 500.0 g of steam at 100.00C condense and cools to
50.00C?
𝑄 = ±𝑚𝐿𝑣 = −(0.500 𝑘𝑔)(2260 𝑘𝐽⁄𝑘𝑔) = −1130 𝑘𝐽 = −1130𝑥103 𝐽
𝑄 = 𝑚𝑐∆𝑇 = (0.500 𝑘𝑔)(4186 𝐽⁄𝑘𝑔 ∙ ℃)(50.0 ℃ − 100.0 ℃) = −1.04𝑥105 𝐽
𝑄𝑡𝑜𝑡𝑎𝑙 = −1130𝑥103 𝐽 + (−1.04𝑥105 𝐽) = −1.21𝑥106 𝐽
5.) An automobile engine does 520 kJ of work and loses 220 kJ of energy as heat. What is the
change in the internal energy of the engine? Treat the engine, fuel, and exhaust gases as a closed
system.
𝑊 = −520 𝑘𝐽
𝑄 = −220 𝑘𝐽
𝑈 =?
∆𝑈 = 𝑊 + 𝑄 = −520 𝑘𝐽 + (−220 𝑘𝐽) = −740 𝑘𝐽
6.) Calculate the work done on or by a system that absorbs 260 kJ of heat experiences a change
in internal energy of 157kJ.
𝑄 = 260 𝑘𝐽
𝑈 = 157 𝑘𝐽
𝑊 =?
∆𝑈 = 𝑊 + 𝑄
𝑊 = ∆𝑈 − 𝑄 = 157 𝑘𝐽 − 260 𝑘𝐽 = −103 𝑘𝐽