Question

If i mix 1 mole of hydrogen, one mole of oxygen, and 1 mole of nitrogen in a 5 liter container and create a spark in the gas mixture the following reaction occurs

2H2 + O2 -> 2H2O. If the Tempurature after the reaction is 120 degrees C, what is the pressure?

Also, what will the pressure be if the tempurature is reduced to 25C. Ignore the vapor pressure of liquid water.

Answer 1

2H2(g) + O2(g) ---> 2H2O(g)

2 mol H2 = 1 mol O2

If i mix 1 mole of hydrogen, one mole of oxygen, and 1 mole of nitrogen.

LIMITING REACTANT = H2

no of mol of H2 remaining = 0 mol

no of mol of O2 remaining = 0.5 mol

TOTAL no of mol of gases remaining = 1(N2) + 0.5(o2) = 1.5 mol

Ptotal = ?

nTotal = 1.5 mol

R = 0.0821 l.atm.k-1.mol-1

T = 120 c = 120+273.15 = 393.15 k

V = 5 L

PV = nRT

Ptotal = nRT/V = 1.5*0.0821*393.15/5 = 9.7 atm

if T - reduced to 25 c.

Ptotal = nRT/V = 1.5*0.0821*298.15/5 = 7.343 atm