Determine the mole fractions and partial pressures in

  • No School
  • AA 1
  • 32

This preview shows page 10 - 20 out of 32 pages.

Determine the mole fractions and partial pressures (in kPa) of both gases at 25.0 °C. T = 25.0 °C + 273.15 = 298.15 K M O2 = 31.998 g/mol, M He = 4.0026 g/mol R = 8.314 L kPa mol -1 K -1 Mole fractions 10
Image of page 10

Subscribe to view the full document.

Example 2: Mole fractions J = N . m = Pa . m 3 11
Image of page 11
Example 2: Mole fractions; use either n or p! Or, Mole fractions 12
Image of page 12

Subscribe to view the full document.

Vapour pressure: the equilibrium pressure of a vapour above a liquid. • p vap is constant for each compound (at constant T) • A liquid with a high p vap will evaporate at a low temperature • p vap T Vapour pressure T (°C) p vap,H2O (Torr) 0 4.579 25 23.756 50 92.51 100 760.0 13
Image of page 13
Knowing the vapour pressure of a specific liquid can help determine the partial pressure of another gas in the mixture Reaching equilibrium p gas = p bar (outside) The trapped gas mixture contains gas + H 2 O (g) Vapour pressure gas in P gas 14
Image of page 14

Subscribe to view the full document.

Reaching equilibrium p gas = p bar (outside) The trapped gas mixture contains gas + H 2 O (g) Where represents the equilibrium of Vapour pressure gas in P gas 15
Image of page 15
Example: Oxygen is collected over water at 21 °C. The total pressure is 741 Torr. What is the partial pressure of O 2 (g)? The vapour pressure of water at 21.0 °C is 18.7 Torr. Vapour pressure 16
Image of page 16

Subscribe to view the full document.

Example 2: What volume of “wet” hydrogen is collected over water at 742 Torr and 23 °C from 1.50 g Al(s)? The vapour pressure of water at 23.0 °C is 21.1 Torr. Vapour pressure 17
Image of page 17
Example 2: Vapour pressure 18
Image of page 18

Subscribe to view the full document.

Example 2: The volume of wet hydrogen is 2.14 L.
Image of page 19
Image of page 20
  • Fall '19

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes