Unit: Gas Laws

1. Unit: Gas Laws Ideal Gas Law

2. After today you will be able to… • Explain what an ideal gas is • Calculate an unknown pressure, temperature, volume, or amount of gas using the ideal gas law equation

3. Ideal Gases • Ideal gases are gases that are said to follow all assumptions of kinetic molecular theory. • An ideal gas is also considered to conform to all gas laws.

4. Ideal Gases • Up until now we have only changed variables such as pressure, volume, and temperature of a gas. • In each of these cases the amount of gas was assumed constant. • The combined gas law can be modified to include the amount of gas by including the variable, n.

5. Ideal Gas Law This gas law relates the amount of gas (in moles) to the volume it would occupy at a particular temperature and pressure.

6. Ideal Gas Law Where, P= pressure (atm) V= volume (L) n= moles (mol) R= 0.0821 L·atm/mol·K T= temperature (K) PV=nRT R is called theIdeal Gas Constant (it has multiple values depending on the pressure unit).

7. Ideal Gas Law Example At what pressure would 0.212 mol of a gas occupy 6.84L at 89°C? P= V= n= R= T= PV=nRT ? • (362K) • (0.0821) • (0.212mol) (P) (6.84L) = 6.84L • P = 0.92atm 0.212mol • 0.0821L·atm/mol·K • 89°C + 273= 362K

8. Ideal Gas Law Example At what temperature would 52.3g of methane (CH4) gas occupy 65.7L at 184kPa? P= V= n= R= T= 184kPa PV=nRT 65.7L 1 molCH4 52.3gCH4 x 3.26 mol CH4 = 16.05gCH4 • 8.31 L·kPa/mol·K • (8.31) • (T) • (3.26mol) (184 kPa) (65.7L) = • ? 447K • T =

9. Questions?