Question

A mouse is placed in a sealed chamber filled with air at 760.0 torr and equipped with enough drying material to absorb any CO2and H2O produced. The gas volume in the chamber is 2.05 L and its temperature is held at 300. K. After 2 hours, the pressure inside the chamber has fallen to 720.0 torr. If molecular oxygen is 20.0% of air, what mass of molecular oxygen has the mouse consumed?

Answer 1

mass of O2 consumed based on pressure change because if oxygen gas is consumed by mouse the pressure exerted by oxygen gas will be down

pressure change = 760 - 720 = 40 torr

760 torr = 1 atm

P = 40 / 760 = 0.05263 atm

V = 2.05 L

T = 300 K

P V = n R T

0.05263 x 2.05 = n x 0.0821 x 300

n = 4.38 x 10^-3

moles of O2 = 4.38 x 10^-3

mass = moles x molar mass

          = 4.38 x 10^-3 x 32

           = 0.140 g

mass of molecular oxygen has the mouse consumed = 0.140 g