Blake Lecture 11-17-08

Blake Lecture 11-17-08 - 5 PV =(mass/molecular weight RT 6...

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Blake 11-17-08 Chemistry Ex 1: What is the T in STP (Standard Temperature Pressure) for gases? 1. 0 K 2. 0 C – ANSWER (ICED WATER) 3. 25 C 4. 100 C Ex 2: What is the volume of one mole of gas at STP? 1. 0 L 2. 22.4 L 3. 24.5 L Ex 3: 100g of dry ice evaporates in a 2L container at 25 C. What is the final P? 1. P = nRT/V 2. P = (100g/44.01GFM = 2.27)(0.0821)(25+273 = 298K) / 2L 3. =27.8 atms 4. 1 atm = 14.7 psi Ex 4: 34g of HCl decomposes into its elements at STP. What is the change in volume? 1. 2HCl = H 2 + Cl 2 V = V f - V i 2. 2 moles of gas 2 moles gas 3. 22.4 L = 1 mole of ? 4. 22.4 * .9315 moles HCl = 20.9 L

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Density of Gas Can we write an equation for the density of a gas? 1. PV = nRT 2. D = mass / volume 3. Relate mass to moles 4. Mass / Molecular Weight = # of moles
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Unformatted text preview: 5. PV = (mass/molecular weight) RT 6. P = (mass / V)(RT / molecular weight) 7. (Molecular weight * P) / RT = mass / V = d Partial Pressure P n • X n = mol n / total mol (mol fraction) • X n P tot = P n • P a + P b + P c etc. = P tot • X a = mole fraction of A = (# mol A/ total # moles) Ex 5: What is the partial pressure of nitrogen in dry air at STP? • 78% Nitrogen, 21% oxygen, 1% Argon • 78 g N, 21 g O, 1 g Ar • 78 N / 28 g = 2.78 moles of N • 21 O / 32 g = 0.66 moles of O • 1 Ar / 40 g = 0.025 moles of Ar • Total moles = 3.47 moles • (2.78 Moles of N/3.47 Total Moles) * 1 = 0.80 atms....
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This note was uploaded on 03/22/2011 for the course CHEMISTRY 1307 taught by Professor Tamarahanna during the Spring '09 term at Texas Tech.

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Blake Lecture 11-17-08 - 5 PV =(mass/molecular weight RT 6...

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