Question c1b62

Nov 20, 2016

Answer:

$\text{Δ_"rxn"H = "-52.0 kJ}$

Explanation:

The equation for the reaction is

$\text{A + 2B" → "D" + "E}$

This is our target equation.

We must create it from equations (1) and (2).

(1) $\textcolor{w h i t e}{l} \text{A" + "2B" → "C"; Δ_"rxn"H = "+22.1 kJ}$

(2) $\text{C" → "D" + "E"; color(white)(ll) Δ_"rxn"H =color(white)(l) "-74.1 kJ}$

We start with Equation (1) because it contains $\text{A}$.

Then we add Equation (2) to eliminate compound $\text{C}$ that is not in our target equation:

(1): $\textcolor{w h i t e}{m} \text{A" + "2B" → color(red)(cancel(color(black)("C"))) color(white)(mmll)Δ_"rxn"H = "+22.1 kJ}$

+(2): color(red)(cancel(color(black)("C"))) color(white)(mml)→ "D" + "E" color(white)(m)Δ_"rxn"H = color(white)(l)"-74.1 kJ"

color(white)(mml)stackrel(————————)("A" + "2B" → "D" + "E")color(white)(ml) Δ_"rxn"H = stackrel(————)("-52.0 kJ")#