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Dalton’s Law of Partial Pressures. For a mixture of gases in a container, P Total = P 1 + P 2 + P 3 + . . . . Collecting gas over H 2 O. Dalton’s Law of Partial Pressures. For gases collected over water: P gas = P atm – P H2O.
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Dalton’s Law of Partial Pressures For a mixture of gases in a container, PTotal = P1 + P2 + P3 + . . .
Dalton’s Law of Partial Pressures For gases collected over water: Pgas = Patm – PH2O
How many grams of magnesium are required to yield 1.12 liters of H2 collected by displacement of water at 26oC and 748 torr? (Vapor pressure: 3.4 kPa or 25.5 torr) Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)
Partial Pressures • Mole Fraction (Xgas) • = mols of gas/total mols of gases in mixture • Xgas = ngas/ntotal
Calculate the total pressure (in atm) of a mixture that contains 1.00 gram of H2 and 1.00 gram of He in a 5.00-liter container at 21oC. What are the partial pressures of the H2 and He?
Two flasks are connected with a stopcock. The first flask has a volume of 5 liters and contains nitrogen gas at a pressure of 0.75 atm. The second flask has a volume of 8 L and contains oxygen gas at a pressure of 1.25 atm. When the stopcock between the flasks is opened and the gases are free to mix, what will the pressure be in the resulting mixture?
Practice Problems How many grams of antimony(III) chloride can be produced from 3570 cm3 of chlorine at STP reacting with an excess of antimony? 2 Sb(s) + 3 Cl2(g) 2 SbCl3(s Ans. 24.437 g SbCl3 What volume of oxygen can be collected by displacement of waterat 745 torr and 23oC by the complete decomposition of 5.00 g of KClO3? (H2O = 2.8 kPa or 21 torr) 2 KClO3(s) + heat 2 KCl(s) + 3 O2(g) Ans. 1.553 liters What’s the partial pressure of carbon dioxide in a container that holds 5 moles of carbon dioxide, 3 moles of nitrogen, and 1 mole of hydrogen and has a total pressure of 1.05 atm? Ans. 0.583 atm