1. No category

1. A nonsugar sweetener provides 16,000 J of nutritional energy per serving. What
is this energy in kilocalories?
2. The specific heat of nickel is 0.445J/goC. How much heat is required to heat a
168g piece of nickel from –15.2oC to 23.6oC? (answer in J).
3. Suppose a 55.0g piece of metal was heated in boiling water to 99.8oC and then
dropped into water in an insulated cup. There are 225 mL of water (density =
1.00g/mL) in the beaker, and its temperature before the metal was dropped in
was 21.0oC. The final temperature in the cup is 23.2oC. What is the specific
heat of the metal?
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
Use the graph to answer the following questions.
4. Identify the point on the graph where each of the
following occurs.
Melting begins
______
Freezing begins
______
Boiling begins
______
Condensation begins ______
5. Does the substance release or absorb heat as it goes from D to C?
6. Why does the temperature remain constant during a phase change from E to F?
7. Explain what happens to volume as water temperature goes from 4oC to 0oC and
freezes solid.
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
8. How much heat will a 15.448 g sample of copper at 95.3°C lose in cooling to
36.5°C? The specific heat of copper is 0.092 cal/g°C.
9. If you know the specific heat of a metal, you can predict the outcome of a
calorimetry experiment. If you put a 15.448 g sample of copper at 95.3°C in 40.0
g water initially at 24.5°C, what will the final temperature of the system be? Use
your phone to find the specific heat of copper metal! (in your practice packet as
well)
10. Find the heats of the reaction for the following. State whether the reaction is
endothermic or exothermic.
a) 2H2O2(l)  2H2O(l) + O2(g)
b) HCl(g) + NaOH(s)  NaCl(s) + H2O(l)
c) CH4(g) + Cl2(g)  CH3Cl(g) + HCl(g)
NaCl(s)
NaOH(s)
CH3Cl(g)
H2O2 (l)
CH4(g)
H2O(l)
Cl2(g)
HCl(g)
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
-410.9
-425.6
-82.0
-187.8
-92.30
-285.83
0
-92.30
11. How much heat is released when 4.50 g of methane gas (CH4) is burned?
CH4(g) + 2O2(g)  CO2(g) + 2H2O(l) ΔH = -890 kJ
12. How much heat is needed to warm 250.0 g of water (about 1 cup) from 22°C
(about room temperature) to near its boiling point, 98°C?
13. Large beds of rocks are used in some solar-heated homes to store heat.
Assume that the specific heat of the rocks is 0.82 J/g°C. Calculate the
quantity of heat absorbed by 50.0 kg of rocks if their temperature increases by
12.0°C.
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
14. Using the standard enthalpies of formation given below, calculate the enthalpy
change
C2H5OH(l) + 3O2(g)  2CO2(g) + 3H2O(l)
ΔHf°
C2H5OH(l):
ΔHf° CO2(g) :
ΔHf° H2O(l) :
235.1 kJ
393.5 kJ
285.8 kJ
15. A coffee-cup calorimeter contains 150.0g of water at 25.1°C. A 121.0g block
of an unknown metal is heated to 100.4°C by putting it in a beaker of boiling
water. The hot metal is put into the calorimeter and the temperature is observed
and a high temperature of 30.1°C is reached. Determine the specific heat of the
metal.
16. When 182g of gold at some temperature is added to 22.1g of water at a
temperature of 25.0oC, the final temperature of the resulting mixture is 27.5oC.
If the specific heat of gold is 0.128J/goC, what was the initial temperature of the
gold sample?
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
17. Calculate ΔH for the reaction 4 NH3 (g) + 5 O2 (g)  4 NO (g) + 6 H2O (g),
from the following data.
N2 (g) + O2 (g) 2 NO (g)
ΔH = -180.5 kJ
N2 (g) + 3 H2 (g) 2 NH3 (g)
ΔH = -91.8 kJ
2 H2 (g) + O2 (g) 2 H2O (g)
ΔH = -483.6 kJ
18. Calculate ΔH for the reaction CH4 (g) + NH3 (g)  HCN (g) + 3 H2 (g),
given:
N2 (g) + 3 H2 (g) 2 NH3 (g)
ΔH = -91.8 kJ
C (s) + 2 H2 (g)CH4 (g)
ΔH = -74.9 kJ
H2 (g) + 2 C (s) + N2 (g) 2 HCN (g)
ΔH = +270.3 kJ
19. Calculate ΔH for the reaction: NO(g) + O(g)  NO2(g) given the following
information:
NO(g) + O3(g)  NO2(g) + O2(g)
ΔH = -198.9kJ
O3(g)  3/2 O2(g)
ΔH = -142.3 kJ
O2(g)  2O(g)
ΔH = 495.0 kJ
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)
Use the standard enthalpies of formation table to determine the change in enthalpy
for these reactions.
20. NaOH(s) + HCl(g)  NaCl(s) + H2O(g)
21. 2 CO(g) + O2(g)  2 CO2(g)
22. CH4(g) + 2 O2(g)  CO2(g) + 2 H2O(l)
23. 2 H2S(g) + 3 O2(g)  2 H2O(l) + 2 SO2(g)
24. 2 NO(g) + O2(g)  2 NO2(g)
1 calorie = 4.18 Joules
1000 calories = 1 kilocalorie = 1 Calorie
q = mcpΔT
qlost = qgained OR mcpΔT(lost) = – mcpΔT (gained)