Question

What volume of O₂ is needed to react completely with 9.24 L of H₂ to give H₂O, if all gases are measured at 25^o C and one atm? Hint: Write a balance reaction for the production of water from oxygen and hydrogen

Answer 1

first calculate no. of mole of H₂ by using ideal gas equation

PV = nRT             where, P = atm pressure= 1 atm,

V = volume in Liter = 9.24 L

n = number of mole = ?

R = 0.08205L atm mol^-1 K^-1 =Proportionality constant = gas constant,

T = Temperature in K = 25⁰C = 273.15+ 25 = 298.15 K

We can write ideal gas equation

n = PV/RT

Substitute the value

n = (1 X 9.24)/(0.08205 X 298.15) = 0.3777 mole

H₂ given = 0.3777 mole

Balanced chemical reaction is

O₂ + 2H₂   2H₂O

According to reaction 2 mole H₂ required 1 mole of O₂ then to react with 0.3777 mole of H₂ required O₂ = 0.3777/2 = 0.1889

O₂ required = 0.1889 mole

to calculate volume of O₂ use ideal gas equation

We know that PV = nRT

V = nRT/P

n = 0.1889 mole

T = 25⁰C = 25 + 273.15 = 298.15K,

P= 1 atm,

R = 0.08205 L atm mol^-1 K^-1 ( R = gas constant)

V = ?

Substitute these value in above equation.

V = (0.1889 X 0.08205 X 298.15 ) / 1  = 4.62 L

4.62 liter O₂ required