DO NOW: Complete on the BACK of the NOTES! The volume of a gas is 550 mL at 960 mm Hg and 200.0 oC. What volume would the pressure of the gas be 830 mm Hg if the temperature is reduced to 150.0oC? At what temperature (in oC) would a gas have a volume of 13.5 L at a pressure of 0.723 atm, if it had a volume of 17.8 L at a pressure of 0.612 atm and a temperature of 28.0oC?

Notes Unit: Gas Laws Ideal Gas Law

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

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.

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.

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.

Ideal Gas Law PV=nRT STOP! It is often called the “picky” law! The units must be what you see here! 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 the Ideal Gas Constant (it has multiple values, but for our purposes we will only use this one).

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

Ideal Gas Law Example PV=nRT At what temperature would 52.3g of methane (CH4) gas occupy 65.7L at 184kPa? P= V= n= R= T= PV=nRT 1 atm 184kPa x = 1.82 atm 101.3kPa 65.7L 1 mol CH4 52.3gCH4 x = 3.26 mol CH4 16.05gCH4 0.0821L·atm/mol·K (1.82atm) (65.7L) = (3.26mol) (0.0821) (T) ? T = 447K

Questions? Complete WS