Question

how many moles of no₂ form when 63.25 g n₂o₅ decompose? 2n₂o₅ → 4no₂ + o₂ ? mol no₂

Explanation:

Step1: Calculate moles of \(N_2O_5\)

Molar mass of \(N_2O_5=(2\times14)+(5\times16)=108\space g/mol\)
Moles of \(N_2O_5=\frac{mass}{molar\space mass}=\frac{63.25\space g}{108\space g/mol}\approx0.5856\space mol\)

Step2: Use mole ratio from balanced equation

From \(2N_2O_5
ightarrow4NO_2 + O_2\), mole ratio \(N_2O_5:NO_2 = 2:4 = 1:2\)
Moles of \(NO_2=2\times\)moles of \(N_2O_5\)
Moles of \(NO_2 = 2\times0.5856\space mol = 1.1712\space mol\)

Answer:

\(1.17\space mol\) (rounded to three significant figures)