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7.3 Thermochemical Equations

Total questions: 10

Worksheet time: 3hrs 30mins

Name
Class
Date
1.

Calculate ΔH when 2 moles of ethanol (C2H5OH) reacts with excess oxygen according to the following thermochemical equation?

C2H5OH + 3O2 → 2CO2 + 3H2O ΔH = −1366.7 kJ

a)

-2733.4 kJ

b)

-683.35 kJ

c)

-1366.7 kJ

d)

-910.67 kJ

2.

What will ΔH be if there is 1 mole of oxygen?

4Fe(s) + 3O2(g) --> 2Fe2O3(s) ΔH = –1500 kJ

a)

-500 kJ

b)

500 kJ

c)

-750 kJ

d)

-4500 kJ

3.

What is ΔH if 2 mol of O2(g) is reacted in this reaction?

H2(g) + ½ O2(g) → H2O(l) ∆H = -285.8 kJ

a)

-570 kJ

b)

-71.45 kJ

c)

-1143.2 kJ

d)

-142.9 kJ

4.
What mass of P4 must be reacted to produce 5905 kJ of energy?
P4 + 6Cl2 --> 4PCl3 + 2439 kJ
a)
25.43 g
b)
563.0 g
c)
2.421 g
d)
300.0 g
5.
Refer to the following question:
2N2 + 3H2 --> 2NH3 + 46 kJ
How much energy would be produced if only 1 mol of nitrogen was reacted?
a)
92 kJ
b)
0.143 kJ
c)
23 kJ
d)
15 kJ
6.

C+ O2 --> CO2 + 60kJ, what heat is released for the reaction if 3 moles of CO2 is formed?

a)

60 kJ

b)

120 kJ

c)

180 kJ

d)

20 kJ

7.

A negative ΔH means the reaction is:

a)

complete

b)

at equilibrium

c)

exothermic

d)

endothermic

8.

A positive ΔH means the reaction is:

a)

complete

b)

at equilibrium

c)

exothermic

d)

endothermic

9.

If ΔT is positive then heat is being ___________by the reaction, and if  ΔT is negative then heat is being _____________by the reaction.

a)

absorbed, released

b)

released, absorbed

c)

heat is staying the same

d)

There is no way to know what is going on with the heat.

10.

A hot iron ball having a mass 0.2 g and at

655°C655\degree C  is mixed with 5.0 g of water at  10°C10\degree C . If the specific heat capacity of iron is 0.449 J/gC, what is the final temperature of the mixture? Assume the specific heat of the water is 4.184 J/gC

a)

 13°C

b)

 28°C

c)

 55°C

d)

 81°C