Question

the density of an unknown gas is 1.107g/L at 300K and 740 mmHg. Could this gas be CO or CO2? Oxygen is generated by the thermal decomposition of potassium chlorate: 2KClo3(s) -> 2 KCl(s) + 3 o2(g) How much KClO3 is needed to generate 200.0 L of O at .85atm and 273K

Answer 1

1) PV = nRT

PV = MRT / MW

P = dRT /MW

MW = dRT/ P

d = 1.107 g /L , R = 0.0821 L.atm / mol.K

T = 300 K , P = 740 mmHg = 0.974 atm

MW = (1.107 x 0.0821 x 300 / 0.974)

MW = 28.0 g /mol

CO = 28.0 g /mol

so gas = CO.

2) calculate the moles O2 gas.

PV = nRT

n = (PV / RT)

n = (0.85 x 200 / 0.0821 x 273)

n = 170 / 22.41

n = 7.58 .

now

according to balanced reaction

3 moles O2 require 2 x 122.55 g KClO3

7.58 moles O2 require 7.58 x 2 x122.55 / 3 = 619.3 g

mass of KClO3 required = 619.3 g