Several properties of gases can be experimentally measured: temperature, pressure, volume, and the amount of the gas (i.e., the number of moles). The ideal gas law states that the relationship between these properties, or variables, in a mathematical formula.
The ideal gas law is PV = nRT.
P is the pressure in atmospheres (atm), V is the volume in liters (L), n is the number of moles, R is the gas constant (0.0821 L∙atm/(mol∙K)), and T is the temperature in Kelvins (K).
Consider the following conditions: a sample of neon gas was under 3.0 atm of pressure, a volume of 570 mL with a temperature of 75 °C.
Assume you are going to use the ideal gas law to solve for the unknown variable.
What variable are you solving for?
Are all of variables in the correct units? If not, which variable needs to be converted to the correct units?
In this scenario, we are solving for the number of moles of neon gas (n).
Not all variables are in the correct units. The volume is given in milliliters (mL) and needs to be converted to liters (L) for the ideal gas law equation. 1 L = 1000 mL, so the volume of 570 mL should be converted to 0.570 L.
Now the variables are in the correct units:
P = 3.0 atm
V = 0.570 L
n = unknown
R = 0.0821 L∙atm/(mol∙K)
T = 75°C + 273 = 348 K
Now we can substitute these values into the ideal gas law equation (PV = nRT) and solve for n.