Question

After the completion of a gas forming reaction, the column of water remaining in the collection flask was measured to me 55mm high, the vapor pressure of water is 0.0313atm at 25oC, and the atmospheric pressure that day was measured as 0.950 atm, what is the partial pressure of the gas produced by the reaction? 1mmHg=13.595mm H2O and 1atm=760mmHg (see sample calculation found in prelab slides.)

Answer 1

Partial pressure of gas = 0.913 mmHg

Step-by-step explanation:

Since the column of water in the tube is higher than in the container, it means that the atmospheric pressure is greater than the gas pressure.

Also, since the gas is collected over water, the total gas pressure is due to partial pressure of the gas and the partial pressure of water vapor, i.e.,

Hence, Partial pressure of gas = Patm - Pressure due to height of water column - Partial pressure of water

Pressure due to height of water column = 55 mmH₂O

Since 13.595 mmH₂O = 1 mmHg

55 mmH₂O = 55/13.595 mmHg

Converting to 55/13.595 mmHg to atm

Pressure due to height of water column = (55/13.595 mmHg) * (1 atm/760 mmHg) = 0.00532

Partial pressure of gas = (0.950 - 0.00532 - 0.0313) atm

Partial pressure of gas = 0.913 mmHg