At 2730 °c, hydrogen molecules dissociate into hydrogen atoms according to the equation h2 (g) → 2 h(g). 10.0 g h2 (g) is placed into a 100.0-l container, sealed and heated to 2730 °c so that the hydrogen molecules begin to dissociate. what is the partial pressure of hydrogen molecules and the total pressure within the container once 25% of h2 has dissociated?

Partial pressure of hydrogen molecule = 9·246 atm

Total pressure within the container = 15·41 atm

Explanation:

Given chemical equation

H2 (g) → 2 H(g)

For every 1 mole of hydrogen molecule dissociated, 2 moles of hydrogen atoms is formed

Given number of moles of hydrogen molecule = 10 ÷ 2 = 5

As 25% of H2 is dissociated, it means that 5 ÷ 4 moles of hydrogen molecule is dissociated

Number of moles of hydrogen atom formed = 2 × 1·25 = 2·5

Remaining moles of hydrogen molecule = 5 - 1·25 = 3·75

Assuming that both hydrogen molecule and hydrogen atom as ideal gases

where P is the pressure of the gas

V is the volume occupied by the gas

n is the number of moles of gas

R is the ideal gas constant

T is the temperature of the gas

Let the partial pressure of hydrogen molecule be P atm

Applying ideal gas equation to the hydrogen molecule

V = 100 L

n = 3·75

T = 2730°C = 2730 + 273 K = 3003 K

P × 100 = 3·75 × 0·0821 × 3003

∴ P = 9·246 atm

Let be the partial pressure of hydrogen atom

Applying ideal gas equation to the hydrogen atom

V = 100 L

n = 2·5

T = 2730°C = 2730 + 273 K = 3003 K

× 100 = 2·5 × 0·0821 × 3003

∴ = 6·164 atm

Total pressure within the container = P +   = 9·246 + 6·164 atm = 15·41 atm

∴ Total pressure = 15·41 atm

see earlier answer