Recitation for Chapter 5
1) The value of ∆H° for the reaction below is -126 kJ. _________kJ are released when 2.00 mol of NaOH is
formed in the reaction? 63
2 2 2 2
2Na O (s) + 2H O (l) 4NaOH (s) + O (g)
→
2) The value of ∆H° for the reaction below is -126 kJ. The amount of heat that is released by the reaction
of 25.0 g of
2 2
Na O
with water is __________ kJ. 20.2
2 2 2 2
2Na O (s) + 2H O (l) 4NaOH (s) + O (g)
→
3) The value of ∆H° for the reaction below is -6535 kJ. __________ kJ of heat are released in the combustion
of 16.0 g of
6 6
C H (l)
?673
6 6 2 2 2
2C H (l) + 15O (g) 12CO (g) + 6H O (l)
→
4) The molar heat capacity of a compound with the formula
2 6
C H SO
is 88.0 J/mol-K. The specific heat of this
substance is __________ J/g-K. 1.13
5) The temperature of a 15-g sample of lead metal increases from 22°C to 37°C upon the addition of 29.0 J of
heat. The specific heat capacity of the lead is __________ J/g-K. 0.13
6) The ∆H for the solution process when solid sodium hydroxide dissolves in water is 44.4 kJ/mol. When a
13.9-g sample of NaOH dissolves in 250.0 g of water in a coffee-cup calorimeter, the temperature increases from
23.0°C to ________°C. Assume that the solution has the same specific heat as liquid water, i.e., 4.18 J/g-K.
37.0°C
7) ∆H for the reaction
5 3 2
IF (g) IF (g) + F (g)
→
is __________ kJ, give the data below. +355
2 3
IF (g) + F (g) IF (g) H = -390 kJ
→ ∆
2 5
IF (g) + 2F (g) IF (g) H = -745 kJ
→ ∆
8) Calculate ∆H° (in kJ) for reaction 3.
2 3
2S (s) + 3O (g) 2SO (g) H = -790 k
J
→ ∆
2 2
S (s) + O (g) SO (g) H = -297
kJ
→ ∆
the enthalpy of the reaction in which sulfur dioxide is oxidized to sulfur trioxide
2SO
2
(g) + O
2
(g) → 2SO
3
(g)
is __________ kJ. -196
9) The value of ∆H° for the reaction below is -186 kJ.
2 2
H (g) + Cl (g) 2HCl (g)
→
The value of
o
f
∆H
for HCl (g) is __________ kJ/mol. -93.0
10) Which one of the following is an exothermic process?
A) ice melting
B) water evaporating
C) boiling soup
D) condensation of water vapor
E) Ammonium thiocyanate and barium hydroxide are mixed at 25°C: the temperature drops.
