Question

In a closed 1.00 L flask, 3.20 atm of CO reacts with 1.20 atm of O2 according to the equation below. Assuming that the temperature remains constant, what is the final pressure in the flask?

2 CO(g) + O2(g) ? 2 CO2(g)

A.4.60 atm B. 1.20 atm C. 1.60 atm D. 3.20 atm

Answer 1

V = 1L

PCO = 3.2 atm

PO2 = 1.2 atm

T = ct.

P final?

2 CO(g) + O2(g) -> 2 CO2(g)

2 mol of CO react with 1 mol of O2 to form 2 mol of CO2

2 atm of CO react with 1 atm of O2 to form 2 atm of CO2

Find the limiting reactant:

3.2 atm of CO need 3.2/2 mol of O2 that is 1.6 mol of O2 are needed... We only have 1.2 so O2 is the limiting reactants:

1.2 atm of O2 will react with 2x1.2 mol of CO, that is 2.4 mol of CO to produce 2.4 mol of CO2

Calculate final pressures:

CO = 3.2-2.4 = 0.80

O2 = 1.2 - 1.2 = 0.0

CO2 = 0+2.4

Final pressures: addition of partial pressures

P = 0.80 atm + 2.4 atm = 3.2 atm

Answer is D) 3.2 atm