Question

A gas decomposes to hydrogen and a liquid in a compressed cylinder of 16 liters. Assuming 298 K, find the maximum pressure the cylinder can withstand (ie, the pressure of hydrogen gas). Formula: 5A(g)-> 2B(l)+ 4H2(g)

Mass of A initial: 2000 g
Molar Mass of A: 30 g/mol
Molar Mass of B: 70 g
Density of B: 600 g/mL

If you can't assume Ideal Gas, how would one do this with Vapor Pressures?

Answer 1

Number of moles of A , n = Mass/molar mass

                                     = 2000 g / 30(g/mol)

                                     = 66.67 mol

The balanced reaction is : 5A(g) ----> 2B(l) + 4H2(g)

From the balanced reaction ,

5 moles of A produces 4 moles of H2

66.67 moles of A produces M moles of h2

M = ( 66.67 x 4) / 5

    = 53.33 mole of H2

We know that , PV = nRT

Where

P = Pressure = ?

V = volume = 16 L

n = number of moles = 53.33 moles

R = gas constant = 0.0821 Latm/(mol-K)

T = temperature = 298 K

Plug the values we get P = ( nRT) / V

                                      = 81.5 atm

Therefore the maximum pressure that the cylinder withstand is 81.5 atm