Question

Calculate ΔH for the reaction: C(graphite) + 2H 2(g) + 1/2 O 2(g) => CH 3OH(l) Using the following information: C(graphite) + O 2 => CO 2(g) ΔH o = -393.5 kJ H 2(g) + 1/2 O 2 => H 2O(l) ΔH o = -285.8 kJ CH 3OH (l) + 3/2 O 2(g) => CO 2(g) + 2H 2O(l) ΔH o = -726.4 kJ a. +238.7 kJ b. -238.7 kJ c. +548.3 kJ d. -548.3 kJ e. +904.5 kJ

Answer 1

`\Delta H` for the given reaction is -238.7 kJ

Step-by-step explanation:

The given reaction can be written as summation of three elementary steps such as:

`C(graphite)+O_(2)(g)\rightarrow CO_(2)(g)`
`\Delta H_(1)= -393.5 kJ`

`2H_(2)(g)+O_(2)(g)\rightarrow 2H_(2)O(l)`
`\Delta H_(2)= (2* -285.8)kJ`

`CO_(2)(g)+2H_(2)O(l)\rightarrow CH_(3)OH(l)+(3)/(2)O_(2)(g)`
`\Delta H_(3)= 726.4 kJ`

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`C(graphite)+2H_(2)(g)+(1)/(2)O_(2)(g)\rightarrow CH_(3)OH(l)`

`\Delta H=\Delta H_(1)+\Delta H_(2)+\Delta H_(3)=-238.7 kJ`