How much heat q is needed to warm 1000 g of water from 15 °C to 45 °C? The specific heat of water is 4.18 J/(g·°C). Give the answer in kJ.
Calorimetry & enthalpy worksheet with answers
1.Easy
m = 1000 gT1 = 15 °CT2 = 45 °Cc = 4.18 J/(g·°C)
q = kJ
2.Easy
How much heat q is needed to warm 100 g of water from 18 °C to 65 °C? The specific heat of water is 4.18 J/(g·°C). Give the answer in kJ.
m = 100 gT1 = 18 °CT2 = 65 °Cc = 4.18 J/(g·°C)
q = kJ
3.Medium
A 250 g block of lead (c = 0.129 J/(g·°C)) at 180 °C is dropped into 100 g of water (c = 4.18 J/(g·°C)) at 24 °C in an insulated cup. Find the final temperature Tf.
mmetal = 250 gcmetal = 0.129 J/(g·°C)Tmetal = 180 °Cmwater = 100 gTwater = 24 °Ccwater = 4.18 J/(g·°C)
Tf = °C
4.Medium
A 150 g block of copper (c = 0.385 J/(g·°C)) at 190 °C is dropped into 400 g of water (c = 4.18 J/(g·°C)) at 25 °C in an insulated cup. Find the final temperature Tf.
mmetal = 150 gcmetal = 0.385 J/(g·°C)Tmetal = 190 °Cmwater = 400 gTwater = 25 °Ccwater = 4.18 J/(g·°C)
Tf = °C
5.Hard
Use the standard enthalpies of formation to find ΔH° for the reaction CH4 + 2O₂ → CO₂ + 2H₂O(l).
ΔH°f(CH4) = −74.8 kJ/molΔH°f(CO₂) = −393.5 kJ/molΔH°f(H₂O, l) = −285.8 kJ/molΔH°f(O₂) = 0
ΔH° = kJ
6.Hard
Use the standard enthalpies of formation to find ΔH° for the reaction 2CH3OH + 3O₂ → 2CO₂ + 4H₂O(l).
ΔH°f(CH3OH) = −238.7 kJ/molΔH°f(CO₂) = −393.5 kJ/molΔH°f(H₂O, l) = −285.8 kJ/molΔH°f(O₂) = 0
ΔH° = kJ
Answer key
- 1. q = 125.4 kJ
- 2. q = 19.65 kJ
- 3. Tf = 35.17 °C
- 4. Tf = 30.51 °C
- 5. ΔH° = −890.3 kJ
- 6. ΔH° = −1453 kJ
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