Question

Laboratory ammonia is 14.8 M NH3 (aq) with a density of 0.8980 g/mL. What is the mole fraction of NH3 in the?

Answer 1

Answer:

Mole fraction of ammonia is 0.2918.

Explanation:

Concentration of ammonia = 14.8 M

Density of the solution,d = 0.8980 g/mL

In 1L of solution there are 14.8 moles of ammonia.

Moles of ammonia = 14.8 mol

Mass of ammonia = 14.8 mol × 17 g/mol = 251.6 g

Volume of solution = 1L = 1000 mL

$d=\frac{Mass}{Volume}=0.8980 g/mL$

$0.8980 g/mL=\frac{M}{1000 mL}$

M = 898.0 g

Mass of solution = M = Mass of water + Mass of ammonia

898.0 g = Mass of water + 251.6 g

Mass of water = 898.0 g - 251.6 g = 646.4 g

Moles of water = $n'=\frac{646.4 g}{18 g/mol}=35.9111 mol$

Mole fraction of ammonia :

$=\frac{n}{n+n'}=\frac{14.8 mol}{14.8 mol+35.9111 mol}=0.2918$