Question

If you drop Mg into HCl, you will evolve hydrogen gas. If you perform this reaction over water at a temperature of 298.15 K at a pressure of 0.977 atm, and the vapor pressure of water at this temperature is 0.0313 atm, what is the pressure of hydrogen?

A.718.7 mm Hg
B.760.0 mm Hg
C.742.5 mm Hg
D.766.3 mm Hg

Answer 1

The pressure of hydrogen is 718.7 mmHg. (option a)

Step-by-step explanation:

Total pressure on the system is 0.977 atm.

Vapor pressure of water is 0.0313 atm, so

H₂ pressure = Total pressure - Vapor pressure

H₂ pressure = 0.977 atm - 0.0313 atm = 0.9457 atm

Let's convert atm to mmHg

1 atm ____ 760 mmHg

0.9457 atm ____ (0.9457 atm . 760 mmHg) / 1

= 718.7 mmHg