YOU KNOW
1. (6 pts) Name three different types of energy.
2. (2 pts) What are the units in which energy is measured?
3. (3 pts) What is the difference between heat and temperature?
4. (4 pts) Which one of the following objects would heat up most quickly if left sitting on a hot stove? 1 g of Fe, 1 g of Ni, 10 g of Fe, or 10 g of Ni (Note: the specific heat capacity of Fe is greater than that of Ni). EXPLAIN.
5. (5 pts) How much heat would be required to raise a 55.0 g sample of metal with a heat capacity of .6438 J/g C from 35.0 C to 43.5 C?
6. (6 pts) A pot of water at a temperature of 21.0 C is sitting on a stove. The stove is turned on and the water absorbs 66,000 J of heat. If the water has a mass of 1000.0 g, what will be the final temperature of the water? (The specific heat capacity of water = 4.18 J/g C)
7. Given the following balanced chemical equation and heats of formation
6 H2O + 6 CO2 --> 6 O2 + C6H12O6 dH = ?
Hf H2O = -285.8 kJ/mol Hf C6H12O6
= -1274.5 kJ/mol
Hf CO2 = -393.5 kJ/mol
A) (6 pts) Find the change in enthalpy (dH).
For the following questions, assume that H for the above reaction is equal to -1000.0 kJ/mol.
B) (2 pts) Is this reaction exothermic or endothermic?
C) (3 pts) How much heat would be required to produce 3.5 moles of C6H12O6?
D) (4 pts) How many grams of O2 would be produced if 56.7 kJ of heat was absorbed?
8. (6 pts) 50.0 mL of a HCl solution at an initial temperature of 20.0 C is mixed with 25.0 mL of a NaOH solution at the same temperature. The resulting solution's temperature rises to a maximum value of 23.5 C. Assuming the specific heat capacity of the mixture is 4.20 J/g C, calculate the change in heat for this process.
(3 pts) Is this reaction exothermic or endothermic? Explain.
9. (6 pts) Given the following reactions and the enthalpy changes:
C(s) + O2(g) --> CO2(g)
dH = -393.5 kJ
H2(g) + ½ O2(g) --> H2O(l)
dH = -285.8 kJ
2 C2H2(g) + 5 O2(g) --> 4 CO2(g) + 2
H2O(l) dH = -2598.8 kJ
Calculate the enthalpy change ( H) for the reaction. (Show all reaction additions!)
2 C(s) + H2(g) --> C2H2(g)
10. (8 pts) In an experiment a 30.0 g piece of metal is warmed with 110.0 J of heat and its temperature increases by 4.0 C. Next, a 50.5 g piece of metal is warmed with 300.0 J of heat and its temperature increases by 5.0 C. Can these two pieces of metal be made of the same substance? Use equations to support your answer.
11. (3 pts) If you could put any question at the end of a chemistry
test, what would it be?
Selected Answers
5. 300 J
6. 37 C
7.
9. 226.6 kJ