Volume and Moles

Avogadro’s Law  When the number of moles of gas is doubled (at constant temperature and pressure, the volume doubles.  The volume of gas is directly proportional to the number of moles if temperature and pressure remain constant Avogadro’s Law is written: OR n = number of moles V = Volume

As the number of moles increases, the volume increases and the temperature and pressure remain the same

Using Avogadro’s Law Suppose we have a 12.2-L sample containing 0.50 mol of Oxygen gas at a pressure of 1 atm and temperature of 25 o C. If all of this O 2 is converted to ozone, O 3, at the same temperature and pressure, what will be the volume of ozone formed?  Step 1: Use a balanced equation to determine the mole ratio.  Step 2: Calculate the number of moles of O 3 that will be produced  Step 3: Use the equation and determine the initial and final conditions  Step 4: Solve 3O 2  2O 3

Avogadro’s Law Practice Problems: 1. If mol of hydrogen gas occupies a volume of 2.35 L at a certain temperature and pressure what volume would mol of hydrogen gas occupy under the same conditions? 2. If 1.00 mol of helium occupies a volume of 22.4 L at 273 K and 1.00 atm, what volume will 1.00 g of helium occupy under the same conditions? 3. If 3.25 mol of argon gas occupies a volume of L at a particular temperature and pressure, what volume does mol of argon occupy under the same conditions? 4. If 2.71 g of argon gas occupies a volume of 4.21 L, what volume will 1.29 mol of argon occupy under the same conditions? 5. If 1.5 mol of nitrogen gas (N 2 ) has a volume of 36.7 L and a second sample has a volume of 16.5 L under the same temperature and pressure conditions. How many moles of Nitrogen gas are there in the second sample?