Question

The hydrogen gas formed in a chemical reaction is collected over water at 30.0 ∘C at a total pressure of 736 mmHg

Part A

What is the partial pressure of the hydrogen gas collected in this way?

Part B

If the total volume of gas collected is 722 mL , what mass of hydrogen gas is collected?

Answer 1

part A)

pressure of water at 30 oC = 31.82 mmHg

total pressure = 736 mmHg

partial pressure of H2 = 736 - 31.82 = 704.18 mmHg

partial pressure of H2 = 704 mmHg

Part B)

volume of gas = 722 mL = 0.722 L

pressure = 0.927 atm

temperature = 30 oC = 303 K

P V = n R T

0.927 x 0.722 = n x 0.0821 x 303

n = 0.0269

moles = 0.0269

mass of hydrogen gas = 0.0538 g