A 100 mL flask contains 2.3 µg of O2 at 18◦C

Question

What is the pressure? Answer in units of Torr

Answer 1

Use the Ideal gas law PV = nRT

For R, I use 0.0821 atm*L/(mol °K)

With this value of R, you would have to use Liters and the pressure will be in atm

First, change mL into L:

100 mL x 1 Liter = 0.1L

1000mL

Next we need the moles of O₂:

2.3μg O₂ x (10^-6 g / 1μg) x (1 mol O₂/ 32g O₂) = 7.188 x 10^-8 mol

Plug in and solve for the pressure, then change the pressure into units of torr

Lastly, get the temperature in degrees Kelvin

18°C = (18 + 273)°K = 291°K