# Worksheet Hesses Law

hesses law worksheeet

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• Created by: Minko Syd
• Created on: 05-12-11 16:11

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Hess's Law Worksheet Name:
______ __________________
1. Calculate H 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) H =
180.
5 kJ
N2 (
g)
+ 3
H 2 (
g)
2 NH3 (
g) H =
91.
8 kJ
2
H 2 (
g)
+ O2 (
g)
2 H2O (
g) H =
483.
6 kJ
2. Find H° for the reaction 2H2(g) + 2C(s) + O2(g) C2H5OH(l), using the
following thermochemical data.
C2H5OH (
l)
+
2 O2 (
g)
2 CO2 (
g)
+ 2
H 2O (
l) H =
875
kJ
C (
s)
+ O2 (
g)
C O2 (
g) H =
394.
51
kJ
H2 (
g)
+ ½
O 2 (
g)
H 2O (
l) H =
285.
8 kJ
3. Calculate H for the reaction CH4 (g) + NH3 (g) HCN (g) + 3 H2 (g), given:
N2 (
g)
+ 3
H 2 (
g)
2 NH3 (
g) H =
91.
8 kJ
C (
s)
+ 2
H 2 (
g)
C H4 (
g) H =
74.
9 kJ
H2 (
g)
+ 2
C
(s)
+
N 2 (
g)
2 HCN (
g) H =
+270.
3 kJ

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Heat of Formation Worksheet
Use a standard enthalpies of formation table to determine the change in enthalpy for each of
these reactions.
a) NaOH(s) + HCl(g) > NaCl(s) + H2O(g)
b) 2 CO(g) + O2(g) > 2 CO2(g)
c) CH4(g) + 2 O2(g) > CO2(g) + 2 H2O(l)
d) 2 H2S(g) + 3 O2(g) > 2 H2O(l) + 2 SO2(g)
e) 2 NO(g) + O2(g) > 2 NO2(g)
Compound Hf (kJ/mol) Compound Hf (kJ/mol)
CH4(g) 74.8 HCl(g) 92.3
CO2(g) 393.5 H2O(g) 241.8

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H2SO4(l) 811.3 NO2(g) +33.9
MgSO4(s) 1278.2 SnCl4(l) 545.2
MnO(s) 384.9 SnO(s) 286.2
MnO2(s) 519.7 SnO2(s) 580.7
NaCl(s) 411.0 SO2(g) 296.1
NaF(s) 569.0 SO3(g) 395.2
NaOH(s) 426.7 ZnO(s) 348.0
NH3(g) 46.2 ZnS(s) 202.…read more