WorksheetsThermochemistry
Total questions: 28
Worksheet time: 14mins
Name
Class
Date
1.
Chemical energy is a type of kinetic energy.
a)
True
b)
False
2.
How many calories are in 5.67 kJ?
a)
23,723
b)
1.36
c)
1355
d)
23.7
3.
Choose the FALSE statement.
a)
The total energy in the universe is always changing.
b)
The surroundings are defined as anything that isn't part of the system.
c)
If a system changes energy, the surroundings change energy too.
d)
Energy can convert between kinetic and potential forms.
4.
If a reaction releases 45 kJ of energy, how much energy do the surroundings gain?
a)
-45 kJ
b)
+45 kJ
c)
-90 kJ
d)
+90 kJ
5.
If a reaction feels cold to the touch, it is:
a)
Endothermic
b)
Exothermic
6.
q is the symbol for work.
a)
True
b)
False
7.
An exothermic process has:
a)
-q
b)
+q
c)
-w
d)
+w
8.
A process that does work on the surroundings has a negative sign for w.
a)
True
b)
False
9.
A reaction in a container with a piston feels warm to the touch and pushes the piston up significantly. Which is true?
a)
q is positive, w is positive
b)
q is negative, w is positive
c)
q is positive, w is negative
d)
q is negative, w is negative
10.
A reaction in a balloon feels warm to the touch and the balloon shrinks significantly. Which is true?
a)
q is positive, w is positive
b)
q is negative, w is positive
c)
q is positive, w is negative
d)
q is negative, w is negative
11.
A reaction decreases in volume and feels very cold to the touch. Which is true?
a)
q is positive, w is positive
b)
q is negative, w is positive
c)
q is positive, w is negative
d)
q is negative, w is negative
12.
A process at constant P releases 49 kJ of heat and does 90 kJ of work on the surroundings. What is the internal energy change? Recall that ΔU = q + w.
a)
-41 kJ
b)
+91 J
c)
-139 kJ
d)
+139 J
13.
A process at constant P absorbs 49 kJ of heat and is known to have a total ΔU of 23 kJ . How much work is done? Recall that ΔU = q + w.
a)
-26 kJ
b)
+72 J
c)
-72 kJ
d)
+26 J
14.
At constant volume, ΔU = q.
a)
True
b)
False
15.
At constant pressure, q = ΔH.
a)
True
b)
False
16.
ΔU is always equal to ΔH.
a)
True
b)
False
17.
In which reaction(s) can you assume ΔU is equal to ΔH?
a)
A(g) + B(g) -> C(g)
b)
A(g) + B(g) -> C(g) + D(g)
c)
A(s) + B(s) -> C(l) + D(s)
d)
A(s) -> B(g) + C(g)
18.
If, at constant pressure, a reaction releases heat, what do you know about ΔH?
a)
ΔH is positive
b)
ΔH is negative
c)
The sign of ΔH cannot be determined.
19.
If, at constant pressure, a reaction feels cold, what do you know about ΔH?
a)
ΔH is positive
b)
ΔH is negative
c)
The sign of ΔH cannot be determined.
20.
If, at constant pressure, a reaction is endothermic, what do you know about ΔH?
a)
ΔH is positive
b)
ΔH is negative
c)
The sign of ΔH cannot be determined.
21.
If, under conditions of changing pressure, a reaction releases heat, what do you know about ΔH?
a)
ΔH is positive
b)
ΔH is negative
c)
The sign of ΔH cannot be determined.
22.
If ΔH = 45.0 kJ/mol for the reaction A + B -> C, what is the ΔH for the reaction C -> A + B?
a)
45.0 kJ/mol
b)
-45.0 kJ/mol
c)
90.0 kJ/mol
d)
-90.0 kJ/mol
23.
If ΔH = 45.0 kJ/mol for the reaction A + B -> C, what is the ΔH for the reaction 2C -> 2A + 2B?
a)
45.0 kJ/mol
b)
-45.0 kJ/mol
c)
90.0 kJ/mol
d)
-90.0 kJ/mol
24.
If ΔH = -20.0 kJ/mol for the reaction A + B -> C, what is the ΔH for the reaction 3A + 3B -> C?
a)
20.0 kJ/mol
b)
-20.0 kJ/mol
c)
-60.0 kJ/mol
d)
-40.0 kJ/mol
25.
At constant P = 1 atm, ΔH = -84.4 kJ for the reaction 2C(s) + 3H2(g) -> C2H6(g). This reaction is:
a)
Endothermic and will feel warm.
b)
Exothermic and will feel warm.
c)
Endothermic and will feel cold.
d)
Exothermic and will feel cold.
26.
ΔH = -84.4 kJ for the reaction 2C(s) + 3H2(g) -> C2H6(g). You make 2 moles of C2H6. How much heat is absorbed/released?
a)
-168.8 kJ
b)
168.8 kJ
c)
-84.4 kJ
d)
84.4 kJ
27.
ΔH = -84.4 kJ for the reaction 2C(s) + 3H2(g) -> C2H6(g). If you react 3 moles of C, how much heat is absorbed/released?
a)
126.6 kJ absorbed
b)
126.6 kJ released
c)
253.2 kJ absorbed
d)
253.2 kJ released.
28.
2H2O -> 2H2 + O2 (ΔH = +286 kJ). If you run the reaction in reverse and make 4 moles of H2O, how many kJ did you make?
a)
+1144 kJ
b)
+572 kJ
c)
-1144 kJ
d)
-572 kJ
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