How much heat q is needed to warm 1000 g of water from 26 °C to 60 °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 = 26 °CT2 = 60 °Cc = 4.18 J/(g·°C)
q = kJ
2.Easy
How much heat q is needed to warm 750 g of water from 23 °C to 70 °C? The specific heat of water is 4.18 J/(g·°C). Give the answer in kJ.
m = 750 gT1 = 23 °CT2 = 70 °Cc = 4.18 J/(g·°C)
q = kJ
3.Medium
A 100 g block of iron (c = 0.449 J/(g·°C)) at 120 °C is dropped into 150 g of water (c = 4.18 J/(g·°C)) at 21 °C in an insulated cup. Find the final temperature Tf.
mmetal = 100 gcmetal = 0.449 J/(g·°C)Tmetal = 120 °Cmwater = 150 gTwater = 21 °Ccwater = 4.18 J/(g·°C)
Tf = °C
4.Medium
A 200 g block of iron (c = 0.449 J/(g·°C)) at 180 °C is dropped into 100 g of water (c = 4.18 J/(g·°C)) at 23 °C in an insulated cup. Find the final temperature Tf.
mmetal = 200 gcmetal = 0.449 J/(g·°C)Tmetal = 180 °Cmwater = 100 gTwater = 23 °Ccwater = 4.18 J/(g·°C)
Tf = °C
5.Hard
Use the standard enthalpies of formation to find ΔH° for the reaction C6H12O6 + 6O₂ → 6CO₂ + 6H₂O(l).
ΔH°f(C6H12O6) = −1274 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 2C2H6 + 7O₂ → 4CO₂ + 6H₂O(l).
ΔH°f(C2H6) = −84.7 kJ/molΔH°f(CO₂) = −393.5 kJ/molΔH°f(H₂O, l) = −285.8 kJ/molΔH°f(O₂) = 0
ΔH° = kJ
Answer key
- 1. q = 142.1 kJ
- 2. q = 147.3 kJ
- 3. Tf = 27.62 °C
- 4. Tf = 50.76 °C
- 5. ΔH° = −2802 kJ
- 6. ΔH° = −3119 kJ
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