Problem: From the enthalpies of reaction2C(s) + O2 (g) → 2CO(g)                          ΔH   rxn = -221.0 kJ2C(s) + O2 (g) + 4H2 (g) → 2CH3OH(g)    ΔHrxn = -402.4 kJcalculate ΔH for the reaction:CO(g) + 2H2 (g) → CH3OH(g)(a) -623.4 kJ (b) 623.4 kJ (c) 181.4 kJ (d) -90.7 kJ (e) -181.4 kJ

FREE Expert Solution

We’re being asked to determine the enthalpy change (ΔHrxn) for the chemical reaction:

From the enthalpies of reaction


CO(g) + 2H2 (g) → CH3OH(g)


We can use Hess’s Law to determine the enthalpy change of the overall reaction from the given reactions:


1. 2 C(s) + O2 (g) → 2 CO(g)                                             ΔH1 = -221.0 kJ

2. 2 C(s) + O2 (g) + 4H2 (g) → 2CH3OH(g)                       ΔH2 = -402.4 kJ



We now need to find a combination of reactions that when added up, gives us the overall reaction.


89% (165 ratings)
View Complete Written Solution
Problem Details

From the enthalpies of reaction

2C(s) + O2 (g) → 2CO(g)                          ΔH   rxn = -221.0 kJ
2C(s) + O2 (g) + 4H2 (g) → 2CH3OH(g)    ΔHrxn = -402.4 kJ

calculate ΔH for the reaction:

CO(g) + 2H2 (g) → CH3OH(g)

(a) -623.4 kJ 

(b) 623.4 kJ 

(c) 181.4 kJ 

(d) -90.7 kJ 

(e) -181.4 kJ

Frequently Asked Questions

What scientific concept do you need to know in order to solve this problem?

Our tutors have indicated that to solve this problem you will need to apply the Hess's Law concept. You can view video lessons to learn Hess's Law. Or if you need more Hess's Law practice, you can also practice Hess's Law practice problems.