Ideal Gas Law:
How can individual laws be combined into a single, unified equation?
Place each of the following relationships into the 2 categories below:
Pressure and temperature, pressure and volume, and pressure and moles
Direct Relationship: x=ky Inverse Relationship: xy=k
Pressure and temp Pressure and volume
Pressure and moles
Using the relationships above derive an expression which answers the EQ and contains the
following variables: P, V, n, and T.
PV ~ nT
This is not currently an equation. In order for this to be a true equation, we need to multiply one
side of the equation by a constant. This is called the Ideal Gas Constant, R. Equation becomes:
PV=nRT This is known as the Ideal Gas Law.
Calculate the value of R for 1 mole of a gas at STP which occupies 22.4L. Express your answer to
3 sig figs, and include units. Think about what units it would need in order to cancel out the
other units in the equation.
PV = nRT
1.0atm*22.4L = 1.0mol*R*273K
R=0.0821Latm/molK This is the Ideal Gas Constant
The Ideal Gas Law is used to solve for unknown temperature, pressure, volume, or moles when
all other variables are known. This is used to calculate values for ideal gases.
P(atm), V(L), n(mol), T(K), R=0.0821Latm/molK
1. What volume is occupied by 3.7mol of a gas at a pressure of 1.4atm and a temperature of
2. A child’s lungs can hold 2.20L. How many grams of air do her lungs hold at a pressure of
1.0atm and a body temp of 37oC? GMM of air=29g/mol
3. How many molecules are in a gas at STP and a volume of 230mL?