`Delta_(f)H^(Theta)` per mole of `NH_(3)(g). NO(g)`, and `H_(2)O(l)` are `-11.04 + 21.60` and `-68.32 kcal`, respectively. Calculate the standard heat of reaction at constant pressure and at a constant volume for the reaction:
`4NH_(3)(g) +5O_(2)(g) rarr 4NO(g) +6H_(2)O(l)`

Explanation

To calculate the standard heat of reaction at constant pressure (ΔH) and at constant volume (ΔU) for the reaction:

\[ 4 \text{NH}_3(g) + 5 \text{O}_2(g) \rightarrow 4 \text{NO}(g) + 6 \text{H}_2\text{O}(l) \]

we will follow these steps:

### Step 1: Write the formula for ΔH of the reaction
The standard heat of reaction at constant pressure (ΔH) can be calculated using the formula:
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