Question

Be sure to answer all parts. A sample of ammonia (NH3) gas is completely decomposed to nitrogen and hydrogen gases over heated iron wool. If the total pressure is 789 mmHg after the reaction, calculate the partial pressures of N2 and H2. Enter your answers in scientific notation. PN2 × 10 mmHg PH2 × 10 mmHg

Answer 1

2 NH3 (g) —> N2 (g) + 3 H2 (g)

p           0       0       (initial)

0           x       3x       (final)

final total pressure = x + 3x

789 = 4x

x = 197.25 mmHg

so,

p(N2) = x

= 197.25 mmHg

= 1.97*10^2 mmHg

p(H2) = 3x

= 3*197.25 mmHg

= 5.92*10^2 mmHg

p(N2) = 1.97*10^2 mmHg

p(H2) = 5.92*10^2 mmHg