Find the concentration in Mass Percent

Question

N2O- Henry's law constant is 3.2 x 10^-5 M torr ^-1. If the partial pressure of nitrous oxide in the lungs is 80 torr what is the molarity of nitrous oxide? Find the concentration in mass percent

Answer 1

Henry's law states that the concentration of dissolved gas is proportional to the partial pressure of the gas in the gas phase. The proportionality constant is Henry's Law constant. Mathematically, this is written as....

C = kP

C = concentration

k = Henry's Law constant = 3.2x10^-5 M torr^-1

P = partial pressure = 80 torr

C = (3.2x10^-5 M torr^-1)(80 torr) = 2.56x10^-3 M

Mass percent? Is that mass/volume? If so, that would be as follows:

2.56x10^-3 M = 2.56x10^-3 mol/L

2.56x10^-3 mol/L x 44 g/mol = 0.113 g/L = 0.0113 g/100 ml = 0.0113 % (m/v)

If you are looking for m/m percent, we'd have to know the density of air in the lungs. Sorry, don't know that.