Comments on: Mixture of helium and oxygen are used in scuba diving.? http://www.diveblueplanet.com/scuba-diving-tanks/mixture-of-helium-and-oxygen-are-used-in-scuba-diving Best Scuba Diving Locations Mon, 21 Jun 2010 00:35:13 -0700 http://wordpress.org/?v=2.8.2 hourly 1 By: Steve O http://www.diveblueplanet.com/scuba-diving-tanks/mixture-of-helium-and-oxygen-are-used-in-scuba-diving/comment-page-1#comment-849 Steve O Mon, 04 Jan 2010 02:40:59 +0000 http://www.diveblueplanet.com/scuba-diving-tanks/mixture-of-helium-and-oxygen-are-used-in-scuba-diving#comment-849 find moles, using molar masses: 1.96 g He @ 4.00 g/mole = 0.49 moles Helium 60.8 g O2 @ 32.0 g/mol = 1.90 moles oxygen total moles = 2.39 moles =========================== A) the mole fractions of two gases? Helium: 0.49 moles Helium / 2.39 total moles = 0.205 helium's mole fraction 1.90 mole O2 / 2.39 total moles = 0.795 oxygen's mole fraction ================================= B) their partial pressures? first find total pressure: PV=nRT P(5.00L) = 2.39 moles (0.08206 Litre-atm / mol-K)(298K) total pressure = 11.69 atm B) their partial pressures? Helium: 11.69 (0.205 helium's mole fraction) = 2.396 atm Helium your answer(3sigfigs): 2.40 atm Helium partial pressure Oxygen: 11.69 - 2.40 = 9.29 atm oxygen your answer is: 9.29 atm Oxygen partial pressure =============================== C) total pressure? your answer(3sigfigs): 11.7 atm<br><b>References : </b><br> find moles, using molar masses:
1.96 g He @ 4.00 g/mole = 0.49 moles Helium

60.8 g O2 @ 32.0 g/mol = 1.90 moles oxygen

total moles = 2.39 moles
===========================

A) the mole fractions of two gases?

Helium:
0.49 moles Helium / 2.39 total moles = 0.205 helium’s mole fraction

1.90 mole O2 / 2.39 total moles = 0.795 oxygen’s mole fraction
=================================

B) their partial pressures?

first find total pressure:
PV=nRT
P(5.00L) = 2.39 moles (0.08206 Litre-atm / mol-K)(298K)
total pressure = 11.69 atm

B) their partial pressures?
Helium:
11.69 (0.205 helium’s mole fraction) = 2.396 atm Helium
your answer(3sigfigs): 2.40 atm Helium partial pressure

Oxygen:
11.69 – 2.40 = 9.29 atm oxygen
your answer is: 9.29 atm Oxygen partial pressure
===============================
C) total pressure?

your answer(3sigfigs): 11.7 atm
References :

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