homework_4_answers - Grodin Micah – Homework 4 – Due...

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Unformatted text preview: Grodin, Micah – Homework 4 – Due: Feb 21 2006, 11:00 pm – Inst: Sara Sutcliffe 1 This print-out should have 15 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points Balance the equation ?HCl+?Ca(OH) 2 → ?CaCl 2 +?H 2 O , using the smallest possible integers. The sum of the coefficients is 1. 5. 2. 7. 3. 6. correct 4. 4. Explanation: A balanced equation must have the same number of each kind of atom on both sides of the equation. We find the number of each kind of atom using equation coefficients and composition stoichiometry. For example, we find there are 4 H atoms on the product side: ?H atoms = 2H 2 O × 2H 1H 2 O = 4H The balanced equation is Ca(OH) 2 + 2HCl → CaCl 2 + 2H 2 O and has 1 Ca, 4 H, 2 Cl and 2 O atoms on each side. ? sum coefficients = 1 + 2 + 1 + 2 = 6. 002 (part 1 of 1) 10 points Sulfur dioxide (SO 2 ) is an unwelcome result of burning soft coal in power plants. Some of the SO 2 ends up as sulfuric acid in acid precipitation. The net reaction is 2SO 2 (g) + O 2 (g) + 2H 2 O( ‘ )-→ 2H 2 SO 4 ( ‘ ) What mass in grams of SO 2 is needed to react with 1950 g of O 2 ? Correct answer: 7808 . 53 g. Explanation: m O 2 = 1950 g m SO 2 = ? mole ratio : 2 mol SO 2 1 mol O 2 . molarmassof SO 2 = 1 × 32 . 07 gS molS + 2 × 16 . 00 gO molO = 32 . 07 g / mol + 32 . 00 g / mol = 64 . 07 g / mol molarmassof O 2 = 2 × 16 . 00 gO molO = 32 . 00 g / mol m SO 2 = 1950 gO 2 × molO 2 32 . 00 gO 2 × 2 molSO 2 1 molO 2 × 64 . 07 gSO 2 molSO 2 = 7808 . 53 g SO 2 003 (part 1 of 1) 10 points Nitrogen dioxide (NO 2 ) is a serious air pol- lutant that is formed when fuels are burned in air. Some of the NO 2 reacts with water in the air as shown below to form nitric acid (HNO 3 ), a major contributor to acid rain. Suppose that 4 . 2 tons of NO 2 are released into the atmosphere, and that 100% of this NO 2 reacts as shown....
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This homework help was uploaded on 04/07/2008 for the course CH 304k/305k taught by Professor Sutcliffe during the Fall '05 term at University of Texas.

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homework_4_answers - Grodin Micah – Homework 4 – Due...

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