Question

How many molecules are in a 100 mL container of gaseous oxygen if the pressure is 2.30x10^ -7 torr and the temperture is 1105 k?

b. How many grams of oxygen are in the container?

Answer 1

First calculate mole of oxygen

Use ideal gas equation for calculation of mole of gas

Ideal gas equation

PV = nRT             where, P = atm pressure= 2.30 10^-7 torr = 3.026 10^-10 atm,

V = volume in Liter = 100 ml = 0.1 L

n = number of mole = ?

R = 0.08205L atm mol^-1 K^-1 =Proportionality constant = gas constant,

T = Temperature in K = 1105 K

We can write ideal gas equation

n = PV/RT

Substitute the value

n = (3.026 10^-10 0.100)/(0.08205 1105) = 3.33755 10¹³ mole

1 mole of gas contain 6.022 10²³ molecule then  3.33755 10^-13 mole oxygen contain

6.022 10²³ 3.33755 10^-13 = 2.00987 10¹¹ molecule of oxygen

container contain 2.00987 10¹¹ molecule of oxygen

b.) molar mass of O₂ = 31.9988 gm/ mole that mean 1 mole of O₂ = 31.9988 gm then 3.33755 10^-13 mole of O₂ = 3.33755 10^-13 31.9988 = 1.067976 10^-11 gm of oxygen

contianer contain 1.067976   10^-11 gm of oxygen