Blake Lecture 9-8-08

# Blake Lecture 9-8-08 - Ex 1 Which is not the correct...

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Unformatted text preview: 9-8-08 Ex. 1 Which is not the correct formula and the standard state for an element? 1. I2 (l) – CORRECT B/C IT’S NOT A LIQUID @ ROOM TEMP. 2. P4 (s) (Exists at the forth and it’s white phosphorus) 3. F2 (g) 4. All are correct Ex. 2 How many electrons are in an O2- (oxide) ion? 1. 2 2. 6 3. 8 - CORRECT 4. 10 Ex. 3 What is the correct formula for potassium oxide? 1. PO 2. P2O 3. PO2 4. KO 5. K2O - CORRECT 6. KO2 Isotopic Composition -Sum of the parts equal the whole % of one component + % of another component = 100% Fraction of one component + the fraction of another component = 100% -Weighted Average 80% = 7 points = A 20% = 10 points = B [Fraction of class A * (value that they got)] + [Fraction of class B * (value that they got)] = AVERAGE VALUE [0.80 * 7] + [0.20 * 10] = 7.6 average points Boron as an example o B-10 mass is 10.0129 amu, 19.91% of sample o B-11 mass is 11.0093 amu o What is the average mass of boron in the sample o % B-10 + % B-11 = 100% o 19.91 + = 100% o 0.1991 * (10.0129 amu) + 0.8009 * (11.0093 amu) = AVERAGE o 1.9936 amu + 8.8175 amu = 10.81 amu How many eggs are in 2.5 dozen eggs? 1. 2.5 2. 12 3. 24 4. 30 - CORRECT 5. 36 What is C2H4 (Acetylene & Ethene) How many H atoms are in 2.5 moles of C2H4? 1. 10 2. 6.0 x 1023 3. 1.5 x 1024 4. 6.0 x 1024 - CORRECT (1 mole = 6.02 x 1023) * 2.5 moles C2H4= (1.5 x 1024) * 4 = 6.0 x 1024 Formula to % Composition o Acetylene, C2H2 > (part/whole) * 100 = % > % compsition by mass > C - 2 * 12.01 amu = 24.02 amu > H - 2 * 1.0079 amu = 2.016 amu 26.04 amu > C = (24.02 amu/ 26.04 amu) * 100 = 92.24 % Carbon > H = (2.016 amu/ 26.04 amu) * 100 = 7.76 % Hydrogen o Benzene, C6H6 o Describe both in terms of % composition ...
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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 9-8-08 - Ex 1 Which is not the correct...

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