Mixture of helium and oxygen can be used in a scuba diving tanks to help prevent the bends , for a particular dive, 46L He and 12L O2 both at 25 degrees Celsius and 1.0atm were pumped into a tank with a volume of 5.0L. Calculate the partial pressure of each gas and the total pressure in the tank att 25 degrees Celsius?

Answer 1

To calculate the partial pressure of each gas, we can first find the moles of each gas using the ideal gas law:

PV = nRT

Where:
P = pressure
V = volume
n = moles
R = ideal gas constant (0.0821 L.atm/mol.K)
T = temperature in Kelvin

First, we convert the temperature from Celsius to Kelvin:

T = 25 + 273 = 298 K

Now we can calculate the moles of each gas:

For helium:
n(He) = (P*V) / (R*T) = (1 atm * 46 L) / (0.0821 L.atm/mol.K * 298 K) ≈ 1.99 mol

For oxygen:
n(O2) = (1 atm * 12 L) / (0.0821 L.atm/mol.K * 298 K) ≈ 0.41 mol

Now we can calculate the partial pressure of each gas:

For helium:
P(He) = n(He) * RT / V = 1.99 mol * 0.0821 L.atm/mol.K * 298 K / 5.0 L ≈ 9.63 atm

For oxygen:
P(O2) = n(O2) * RT / V = 0.41 mol * 0.0821 L.atm/mol.K * 298 K / 5.0 L ≈ 0.40 atm

Total pressure in the tank:
P(total) = P(He) + P(O2) = 9.63 atm + 0.40 atm ≈ 10.03 atm

Therefore, the partial pressure of helium is approximately 9.63 atm, the partial pressure of oxygen is approximately 0.40 atm, and the total pressure in the tank is approximately 10.03 atm at 25 degrees Celsius.