Chemistry Warm-up-solutions

Chemistry Warm-up-solutions - nanni (arn437) – Chemistry...

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Unformatted text preview: nanni (arn437) – Chemistry Warm-up – CNS – (87654) 1 This print-out should have 32 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Simplify parenleftbigg u 3- 2 w parenrightbigg 4 Your answer should be written with all ex- ponents expanded as far as they can go. De- note division using \ , and use the minimum number of parenthesis consistent with order of operations. Correct answer: u 1 2 / (16 w 4 ). Explanation: First we expand the exponent over the things included in the outer parenthesis, and then we simplify as much as we can: parenleftbigg u 3- 2 w parenrightbigg 4 = ( u 3 ) 4 (- 2) 4 w 4 = u 1 2 16 w 4 002 10.0 points Simplify (2 z 5 w 3 )(5 w 7 )(2 z ) Your answer should be written with all ex- ponents expanded as far as they can go. De- note division using \ , and use the minimum number of parenthesis consistent with order of operations. Correct answer: 20 * ( z 6 ) * ( w ( 10)). Explanation: We simply multiply all the like terms, re- membering that ( a n )( a m ) = a n + m . So, the right answer is 2 · 5 · 2 z 5+1 w 3+7 = 20 z 6 w 10 003 (part 1 of 4) 10.0 points Balance the following chemical equation by finding values for a,b,c, and d. a C 2 H 5 OH(l) + b O 2 (g) → c CO 2 (g)+ d H 2 O(g) What is a? Correct answer: 1. Explanation: In a chemical reaction matter is neither created nor destroyed. So, we proceed by counting elements on both sides. C 2 H 5 OH(l) + O 2 (g) → CO 2 (g)+ H 2 O(g) Carbon appears only once on each side of the equation, so to balance the C, we put a 2 in front of the CO 2 and a 1 in front of the C 2 H 5 OH(l) Next the hydrogen. Each molecule of C 2 H 5 OH contains 6 hydrogen atoms. To bal- ance the H, we put a 3 in front of the water. Finally, we match the oxygen in the prod- ucts with the number of oxygen atoms needed in the reactants. On the right hand side of the equation we have 7 oxygen atoms. To balance the oxygen we recognize that there is 1 oxygen atom in C 2 H 5 OH(l) so we need to put a 3 in front of the O 2 (g) The balanced reaction is: 1 C 2 H 5 OH(l) + 3 O 2 (g) → 2 CO 2 (g)+ 3 H 2 O(g) 004 (part 2 of 4) 10.0 points What is b? Correct answer: 3. Explanation: See the explanation for part 1. 005 (part 3 of 4) 10.0 points What is c? Correct answer: 2. Explanation: See the explanation for part 1. 006 (part 4 of 4) 10.0 points What is d? nanni (arn437) – Chemistry Warm-up – CNS – (87654) 2 Correct answer: 3. Explanation: See the explanation for part 1. 007 10.0 points Calculate the volume of a sphere with radius of 3.0 μ m. Answer in cm 3 , to 2 significant digits. Note : Volume formulae are provided in ALEKS Your answer must be within ± 5.0% Correct answer: 1 . 1 × 10- 10 cm 3 ....
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This note was uploaded on 09/19/2011 for the course CH 301 taught by Professor Fakhreddine/lyon during the Fall '07 term at University of Texas.

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Chemistry Warm-up-solutions - nanni (arn437) – Chemistry...

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