Question

One mole of carbon powder and 32 g of O2 gas are allowed to react in a closed 2.00 L flask. After the reaction is complete, and the temperature is allowed to equilibrate to 0 ºC, what is the final pressure of CO2 in the flask?

a.

5.00 atm

b.

4.36 atm

c.

3.29 atm

d.

4.12 atm

e.

11.2 atm

Answer 1

Reaction between C and O₂ is:

C(s) + O₂(g) CO₂ (g)

Mass of O₂ = 32 g

Molar mass of O₂ = 32 g/mol

Moles of O₂ = Mass/ Molar mass = 32g/ (32g/mol) = 1 mol

Thus, from reaction 1 mol of C reacts with 1 mol of O₂ to produce 1 mol of CO₂

From Ideal gas equation,

PV = nRT

where P is the pressure of CO₂

V is the volume = 2.00 L

n = 1 mol

R is the gas constant = 0.0821 L.atm/mol.K

T is the temperature = 0^oC = 273.15 K

Thus, P = nRT/ V = (1 mol * 0.0821 L.atm/mol.K*273.15 K) / 2 L = 11.2 atm

Thus, option e is correct