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Using the thermochemical data below
CHEMISTRY · Subjective · A Level · Chemistry · Energetics · Energetics
Problem
Using the thermochemical data below, determine the standard enthalpy change
Δ
H
∘
\Delta H^\circ
Δ
H
∘
(in kJ) for the reaction
1
2
N
2
(
g
)
+
O
2
(
g
)
→
NO
2
(
g
)
\frac{1}{2}\,\text{N}_2\,(g) + \text{O}_2\,(g) \rightarrow \text{NO}_2\,(g)
2
1
N
2
(
g
)
+
O
2
(
g
)
→
NO
2
(
g
)
Reaction 1:
N
2
(
g
)
+
O
2
(
g
)
→
2
NO
(
g
)
\text{N}_2\,(g) + \text{O}_2\,(g) \rightarrow 2\,\text{NO}\,(g)
N
2
(
g
)
+
O
2
(
g
)
→
2
NO
(
g
)
Δ
H
∘
=
+
180.5
kJ
\Delta H^\circ = +180.5\,\text{kJ}
Δ
H
∘
=
+
180.5
kJ
Reaction 2:
2
NO
(
g
)
+
O
2
(
g
)
→
2
NO
2
(
g
)
2\,\text{NO}\,(g) + \text{O}_2\,(g) \rightarrow 2\,\text{NO}_2\,(g)
2
NO
(
g
)
+
O
2
(
g
)
→
2
NO
2
(
g
)
Δ
H
∘
=
−
114.2
kJ
\Delta H^\circ = -114.2\,\text{kJ}
Δ
H
∘
=
−
114.2
kJ
Related theory
Hess's Law
Thermodynamics
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