Answer to Question #112713 in General Chemistry for maria

Question

A self-contained underwater breathing apparatus uses canisters containing potassium superoxide. The superoxide consumes the exhaled by a person and replaces it with oxygen.
4 KO2(s)+2 CO2(g)--> 2 K2CO3(s)+3 O2(g)
What mass of KO2 , in grams, is required to react with 8.40 L of CO2 at 23.0°C and 764 mm Hg?

Mass =____ g

Answer 1

Solution:

According to ideal gas equation: PV = nRT.

P = 764 mmHg = 1.00526 atm.

V = 8.40 L;

R = 0.08206 L atm K^-1 mol^-1;

T = 23.0°C = 296.15 K.

Then,

n = PV / RT

n(CO₂) = (1.00526 atm × 8.40 L) / (0.08206 L atm K^-1 mol^-1 × 296.15 K) = 0.3475 mol

n(CO₂) = 0.3475 mol.

The balanced chemical equation:

4KO₂(s) + 2CO₂(g) --> 2K₂CO₃(s) + 3O₂(g) 

According to chemical equation: n(KO₂)/4 = n(CO₂)/2;

n(KO₂) = 4×n(CO₂)/2 = 2×n(CO₂).

n(KO₂) = 2 × (0.3475 mol) = 0.695 mol.

Mass of KO₂ = Moles of KO₂ × Molar mass of KO₂

The molar mass of KO₂ is 71.1 g/mol.

Then,

Mass of KO₂ = (0.6948 mol) × (71.1 g/mol) = 49.4145 g = 49.41 g

m(KO₂) = 49.41 g.

Answer: Mass of KO₂ is 49.41 g.