Unit 7.3: Gas Law Calculations

IV) (7.3) Gas Law Calculations a) Introduction: i) You can use the ideal gas law to solve a variety of problems 1) One of the four variables, P, V, n, or T, given the values of the other three. 2) The molar mass or density of a gas. b) Final and initial state problems: i) Commonly, you will be asked to find the change of V, P, n, or T of a change in one or more of these variables. ii) The ideal gas law can be used for these calculations iii) In order to do this, you can write the initial and final states of the gas and divide the two ideal gas equations to get a relationship by eliminating the constants. Example

IV) (7.3) Gas Law Calculations c) Calculation of P,V, n, or T i) Frequently, you may have three of these values and be asked to find the fourth. You just need to plug and chug.

IV) (7.3) Gas Law Calculations d) Molar mass and density: i) The ideal gas law offers a simple approach to finding these experimentally. ii) This also works for volatile liquids. iii) All you need to know is the mass of a sample, the volume, the pressure, and the temperature. iv) Some equations that are handy: