Problem: Calculate ΔH for the reaction N2H4 (l) + O2 (g) → N2 (g) + 2H2O (l)given the following data2 NH3 (g) + 3N2O (g) → 4N2(g) + 3H2O (l)      ΔH = -1010 kJN2O (g) + 3 H2 (g) → N2H4 (l) + H2O (l)           ΔH = -317 kJ2NH3 (g) + 1/2 O2 (g) → N2H4 (l) + H2O (l)       ΔH = -143 kJH2 (g) + 1/2 O2 (g) → H2O (l)                            ΔH  = -286 kJ

FREE Expert Solution

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


N2H(l) + O2 (g) → N2 (g) + 2 H2O (l)


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


1. 2 NH3 (g) + 3 N2O (g)  4 N2(g) + 3 H2O (l)      ΔH = -1010 kJ

2. N2O (g) + 3 H(g) → N2H4 (l) + H2O (l)              ΔH = -317 kJ

3. 2 NH3 (g) + 1/2 O(g) → N2H4 (l) + H2O (l)        ΔH = -143 kJ

4. H(g) + 1/2 O(g)  H2O (l)                               ΔH  = -286 kJ


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


83% (165 ratings)
View Complete Written Solution
Problem Details

Calculate ΔH for the reaction 

N2H(l) + O2 (g) → N2 (g) + 2H2O (l)

given the following data

2 NH3 (g) + 3N2O (g) → 4N2(g) + 3H2O (l)      ΔH = -1010 kJ

N2O (g) + 3 H(g) → N2H4 (l) + H2O (l)           ΔH = -317 kJ

2NH3 (g) + 1/2 O(g) → N2H4 (l) + H2O (l)       ΔH = -143 kJ

H(g) + 1/2 O(g) → H2O (l)                            ΔH  = -286 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.

What professor is this problem relevant for?

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

What textbook is this problem found in?

Our data indicates that this problem or a close variation was asked in Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition. You can also practice Chemistry: An Atoms First Approach - Zumdahl Atoms 1st 2nd Edition practice problems.