How much heat q is needed to warm 300 g of water from 15 °C to 80 °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 = 300 gT1 = 15 °CT2 = 80 °Cc = 4.18 J/(g·°C)
q = kJ
2.Easy
How much heat q is needed to warm 400 g of water from 28 °C to 75 °C? The specific heat of water is 4.18 J/(g·°C). Give the answer in kJ.
m = 400 gT1 = 28 °CT2 = 75 °Cc = 4.18 J/(g·°C)
q = kJ
3.Medium
A 200 g block of copper (c = 0.385 J/(g·°C)) at 170 °C is dropped into 400 g of water (c = 4.18 J/(g·°C)) at 20 °C in an insulated cup. Find the final temperature Tf.
mmetal = 200 gcmetal = 0.385 J/(g·°C)Tmetal = 170 °Cmwater = 400 gTwater = 20 °Ccwater = 4.18 J/(g·°C)
Tf = °C
4.Medium
A 100 g block of iron (c = 0.449 J/(g·°C)) at 200 °C is dropped into 250 g of water (c = 4.18 J/(g·°C)) at 25 °C in an insulated cup. Find the final temperature Tf.
mmetal = 100 gcmetal = 0.449 J/(g·°C)Tmetal = 200 °Cmwater = 250 gTwater = 25 °Ccwater = 4.18 J/(g·°C)
Tf = °C
5.Hard
Use the standard enthalpies of formation to find ΔH° for the reaction C2H5OH + 3O₂ → 2CO₂ + 3H₂O(l).
ΔH°f(C2H5OH) = −277.7 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 = 81.51 kJ
- 2. q = 78.58 kJ
- 3. Tf = 26.6 °C
- 4. Tf = 32.21 °C
- 5. ΔH° = −1367 kJ
- 6. ΔH° = −3119 kJ
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