Question

Determine the pressure in atmospheres of 40.0 g of O2 at 415 °C in a 450 mL container. a) 19.2 atm b) 157 atm c) 31.8 atm d) 94.6 atm

Answer 1

Ans :-

Given mass of O₂ = 40.0 g

Molar mass of O₂ = 32.0 g/mol

So,

Number of moles of O₂ = n = Given mass in g / Gram molar mass

= 40.0 g / 32.0 g/mol

= 1.25 mol

Given temperature = T = 273 + 415 = 688 K

Given volume = V = 450 mL = 0.450 L

From ideal gas equation :

PV = nRT ..................(1)

Where,

R = Gas constant = 0.0821 L atm K^-1 mol^-1

Put the values of V, n, R and T in equation (1)

P = nRT/V

P = (1.25 mol x 0.0821 L atm K^-1 mol^-1 x 688 K) / 0.450 L

P = 156.9 atm

P = 157 atm

Therefore, option (b) i.e. 157 atm is the answer.