Question

assume hydrogen gas and oxygen gas react in clouds to produce water vapor. if the temp in the atmosphere is 16 degrees Celsius and the pressure is 0.855 atm what volume of hydrogen gas would be needed to produce 155 grams of water

Answer 1

Molar mass of H2O,

MM = 2*MM(H) + 1*MM(O)

= 2*1.008 + 1*16.0

= 18.016 g/mol

mass(H2O)= 155 g

use:

number of mol of H2O,

n = mass of H2O/molar mass of H2O

=(1.55*10^2 g)/(18.02 g/mol)

= 8.603 mol

This is mol of water produced.

The reaction is:

2 H2 + O2 —> 2 H2O

mol of H2 required = mol of H2O produced

= 8.603 mol

Given:

P = 0.855 atm

n = 8.603 mol

T = 16.0 oC

= (16.0+273) K

= 289 K

use:

P * V = n*R*T

0.855 atm * V = 8.603 mol* 0.08206 atm.L/mol.K * 289 K

V = 239 L

Answer: 239 L