Given the chemical reaction:
[HCl(g) + NH_3(g) \rightleftharpoons NH_4Cl(s) \quad \Delta H = -42 , \text{kcal/mol}]
We want to determine how much energy is released when 9.2 moles of ammonia ((NH_3)) react. To find this, we’ll use the given enthalpy change and the balanced chemical equation.
First, let's write the balanced chemical equation for the reaction:
HCl(g) + NH3(g) -> NH4Cl(s)
According to the equation, one mole of ammonia reacts with one mole of hydrogen chloride to produce one mole of ammonium chloride.
Next, we can calculate the amount of energy released when 1 mole of ammonia reacts using the given enthalpy change:
ΔH = -42 kcal/mol
This means that when 1 mole of ammonia reacts, 42 kcal of energy is released.
Now, we want to find out how much energy is released when 9.2 moles of ammonia react.
Using the proportionality of the reaction, we can set up a ratio:
42 kcal/1 mol = x kcal/9.2 mol
Solving for x, we get:
x = 42 kcal * (9.2 mol) / 1 mol
x = 386.4 kcal
Therefore, when 9.2 moles of ammonia react, 386.4 kcal of energy is released.