Question

Nitric acid is manufactured in the Oswald process, which involves the catalytic oxidation of ammonia according to the following equations: (i) 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) (ii) 2 NO(g) + O2(g) → 2 NO2(g); (iii) 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g); How many gallons of 70.0% (by mass) of concentrated HNO3 solution (density = 1.48 g/mL) can be produced from 1.00 metric tonne (1.00 x 103 kg) of ammonia gas? Assume a 100% yield. (1 gall = 3.7854 L; 1 gallon of concentrated HNO3 weighs 5.60 kg)

Answer 1

(i) 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g)

(ii) 2 NO(g) + O2(g) → 2 NO2(g);

(iii) 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g)

from... 1 metric ton = 10^3 kg = 10^6 g

mol = mass/mW = (10^6)/(17) = 58823.529 mol of NH3

so...

4 mol of NH3 --> 4 mol of NO --> 4 mol of NO2 --> 2.66 mol of HNO3

so

1 mol of NH3 = 2.66/4 mol of HNO3 = 0.665 mol of HNO3

so..

58823.529 mol of NH3 = 58823.529 *0.665 = 39117.64 mol of HNO3

so..

mass of HNO3 = mol*MW =39117.64*63.01 = 2464802.49 grams of HNO3 = 2.46*10^6 g of HNO3...

1 gal = 5.6 kg

x gal = 2464.80 kg

soo

x = 2464.80 /5.6 = 440.1428 gallons of concentrated acid (i.e. at 70%)