Warm UP If you increase the moles of gas: and hold P and T constant, what happens to volume? and hold temperature constant (in a rigid container) what happens to pressure?

The ideal gas law PV=nRT In reactions the amount of gas may change. Look at the reaction N H 2  2 NH 3 Reactants – 4 moles of gas Products – 2 moles of gas The ideal gas law helps to solve problems when the number of moles of gas are important

P V = n R T P, in Kilopascals (kPa) V, in Liters (L) n, number of moles R, 8.31 L*kPa/mol*K T, in Kelvin (K) R = a constant all dimensions must match that of the gas constant Conversions will be necessary. P= Pressure V= Volume n= # of moles R= universal gas constant T= Temperature

How much in a Gas Cylinder ? A gas cylinder has a volume of 20.0L and a pressure of 20,000 kPa when stored at room temperature (27 C). How many moles of gas are in the cylinder? P V = n R T P= V= n= R= T= kPa 20.0L ? 8.31 L*KPa/mol K =300K Solve for n (moles) PV / RT = n

How many balloons? We know how many moles of gas there are in the cylinder. How many prom balloons (2.5L) can be filled with this gas? THINK about how to solve…write out your steps. The pressure changes to 1 atm or kPa So use PV = nRT And solve for Volume V = nRT/P This gives Volume in liters. For #of balloons divide by 2.5

Gas constant in terms of atm kPa = 1.00 atm Find the gas constant in terms of atmospheres.