Chapter 10, Problem 114RQ

*10.114 In one analytical procedure for determining the percentage of nitrogen in unknown compounds, weighed samples are made to decompose to ${\text{N}}_{\text{2}}$, which is collected over water at known temperatures and pressures. The volumes of ${\text{N}}_{\text{2}}$ are then translated into grams and then into percentages.

(a) Show that the following equation can be used to calculate the percentage of nitrogen in a sample having a mass of W grams when the ${\text{N}}_{\text{2}}$ has a volume of V in mL and is collected over water at $t_C$ in $\text{°C}$ at a total pressure of P in torr. The vapor pressure of water occurs in the equation as $P{°}_{H_{2}O}$.

$\text{Percentage N}=0.04459\times \frac{V\left(P-P^o{}_{{\text{H}}_{\text{2}}\text{O}}\right)}{W\left(273+t_C\right)}$

(b) Use this equation to calculate the percentage of nitrogen in the sample described in Problem 10.117.