Problem: Given the following reactionsH2O (l) →H2O (g)                    ΔH = 44.01 kJ2H2 (g) + O2 (g) → 2H2O (g)  ΔH = -483.64 kJthe enthalpy for the decomposition of liquid water into gaseous hydrogeand oxygen2H2O (l) → 2H2 (g) + O2 (g) is __________ kJ.A) -395.62B) -527.65C) 439.63D) 571.66E) 527.65

🤓 Based on our data, we think this question is relevant for Professor Gray's class at CSU.

FREE Expert Solution

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


2 H2O (l) → 2 H2 (g) + O2 (g) 


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


1. H2O (l) →H2O (g)                                                         ΔH1 = 44.01 kJ

2. 2H2 (g) + O2 (g) → 2H2O (g)                                        ΔH2 = - 483.64 kJ


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


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Problem Details

Given the following reactions

H2O (l) →H2O (g)                    ΔH = 44.01 kJ

2H2 (g) + O2 (g) → 2H2O (g)  ΔH = -483.64 kJ

the enthalpy for the decomposition of liquid water into gaseous hydrogeand oxygen

2H2O (l) → 2H2 (g) + O2 (g) 

is __________ kJ.

A) -395.62

B) -527.65

C) 439.63

D) 571.66

E) 527.65

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.

What professor is this problem relevant for?

Based on our data, we think this problem is relevant for Professor Gray's class at CSU.