Sample exam 1 - 1 CHEM 1110 Fall 2009 Sample Test 1 Name E...

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CHEM 1110 Fall 2009 September 21, 2009 Sample Test 1 Name_________________________ E#________________________ You must show all work and use proper units and significant digits for full credit. 1. (15 points) Balance the following equations: a) (3 points) Mg 3 N 2 + H 2 O → Mg(OH) 2 + NH 3 b) (3 points) Fe 2 O 3 + H 2 → Fe + H 2 O c) (3 points) LiHCO 3 + H 2 SO 4 → Li 2 SO 4 + CO 2 + H 2 O d) (6 points) C 12 H 22 O 11 + O 2 → CO 2 + H 2 O 2. (15 points) A compound contains sodium, boron, and oxygen. An experimental analysis gave values of 53.976% sodium and 8.461% boron, by mass; the remainder is oxygen. What is the empirical formula of the compound? (AM of O: 15.9994 u; Na: 22.9898; B: 10.811) 1
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3. (20 points) A 6.789 g sample of a hydrocarbon, upon combustion analysis, yielded 9.883 grams of carbon dioxide. (MM of CO 2 is 44.0095; AM of C: 12.0107, H: 1.00794; N A = 6.022 x 10 23 fu/mol) a) (15 points) What is the mass percent of carbon in this compound? b) (5 points) How many atoms of carbon are in this hydrocarbon? 3. (15 points) Pure chromium metal is prepared from the ore chromite. The ore is converted into sodium dichromate, Na 2 Cr 2 O 7 , which is then reacted with carbon to form the oxide Cr
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