Question

a sample containing 1.20 moles of Ne gas has an initial volume of 7.50 L. What is the final volume of the gas, in liters, when each of the following changes occur in the quantity of the gas at constant pressure and temperature?​
1) a leak allows one half of the Ne atoms to escape
2) a sample of 3.10 moles of Ne is added to the 1.20 moles of Ne gas in the container
3) a sample of 35.0 g of Ne is added to the 1.20 moles of Ne gas in the container.

Answer 1

1) We know that at constant pressure and temperature the volume of a gas is directly proportional to the temperature.

As One half of the Ne atoms have escaped the volume will also be reduced to half.

Therefore, final volume is (7.50/2) L = 3.75 L.

2) We know that at constant pressure and temperature the volume of a gas is directly proportional to the temperature.

The final atom number is (1.20+3.10) mol = 4.30 mol

Therefore, final volume is {7.50 * (4.30/1.20)} L = 26.88 L.

3) We know that at constant pressure and temperature the volume of a gas is directly proportional to the temperature.

Molar mass of Neon is 20.18 g/mol.

Thus 35.0 g of Ne contains (35.0/20.18) mol = 1.73 mol

The final atom number is (1.20+1.73) mol = 2.93 mol

Therefore, final volume is {7.50 * (2.93/1.20)} L = 18.31 L.