CDO AP Chemistry Christman Unit 1 2014

Unit 1 Atoms, Molecules Ion, Stoichiometry Review

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Multiple Choice Questions 1. What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P? (Molar Mass P4O10 = 284)

(A) 0.0500 mole (B) 0.0625 mole (C) 0.125 mole (D) 0.250 mole (E) 0.500 mole

2. A 27.0-gram sample of an unknown hydrocarbon was burned in excess oxygen to form 88.0 grams of carbon dioxide

and 27.0 grams of water. What is a possible molecular formula of the hydrocarbon?

(A) CH4 (B) C2H2 (C) C4H3 (D) C4H6 (E) C4H10

3. How many grams of calcium nitrate, Ca(NO3)2, contains 24 grams of oxygen atoms?

(A) 164 grams (B) 96 grams (C) 62 grams (D) 50. grams (E) 41 grams

CDO AP Chemistry Christman Unit 1 2014

Unit 1 Atoms, Molecules Ion, Stoichiometry Review

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4. The simplest formula for an oxide of nitrogen that is 36.8 percent nitrogen by weight is… (A) N2O (B) NO (C) NO2 (D) N2O3 (E) N2O5

5. What volume will contain 5.0 mol of aluminum? The density of aluminum is 2.7 g/mL

(A) 10. mL (B)20.mL (C) 40. mL (D) 50. mL (E) 100. mL 6. A compound contains 1.10 mol of K, 0.55 mol of Te, and 1.65 mol of 0. What is the simplest formula of this

compound? (A) KTeO (B) KTe2O

(C) K2TeO3

(D) K2TeO6 (E) K4TeO6

CDO AP Chemistry Christman Unit 1 2014

Unit 1 Atoms, Molecules Ion, Stoichiometry Review

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7. The atomic mass of copper is 63.55. Given that there are only two naturally occurring isotopes of copper, 63Cu and 65Cu, the natural abundance of the 65Cu isotope must be approximately

(A) 90% (B) 70% (C) 50% (D) 25% (E) 10%

8. Propane gas, C3H8, burns in excess oxygen gas. When the equation for this reaction is correctly balanced and all

coefficients are reduced to their lowest whole-number terms, the coefficient for O2 is

(A) 4 (B) 5 (C) 7 (D) 10 (E) 22

2 N2H4(g) + N2O4(g) 3 N2(g) + 4 H2O(g)

9. When 8.0 g of N2H4 (32 g mol-1) and 92 g of N2O4 (92 g mol-1) are mixed together and react according to the

equation above, what is the maximum mass of H2O that can be produced?

(A) 9.0 g (B) 18 g (C) 36 g

(D) 72 g (E) 144 g

CDO AP Chemistry Christman Unit 1 2014

Unit 1 Atoms, Molecules Ion, Stoichiometry Review

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Free Response Questions 1. This unbalanced chemical equation is relevant to both parts (a) and (b) of this question

Fe3O4 + H2 Fe + H2O (a) Iron ore, in the form of the mixed iron oxide shown, can be reduced by the addition of hydrogen gas. How many grams of Iron metal will be produced in the process, if 411 g of Fe3O4 are reacted completely with hydrogen gas? b) Determine the amount of water produced in this reaction in moles, if 12.01 g of iron ore are reacted with sufficient hydrogen to convert it to products, in such a way that the reaction has a 48.22 % yield.

2. The molecular formula of a hydrocarbon is to be determined by analyzing its combustion products and investigating its colligative properties. The hydrocarbon burns completely, producing 7.2 grams of water and 7.2 liters of CO2 at standard conditions (volume of 1 mole of gas at standard conditions = 22.4 L). What is the empirical formula of the hydrocarbon?

CDO AP Chemistry Christman Unit 1 2014

Unit 1 Atoms, Molecules Ion, Stoichiometry Review

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3. Answer the following questions about BeC2O4(s) and its hydrate.

(a)Calculate the mass percent of carbon in the hydrated form of the solid that has the formula BeC2O4•3H2O.

(b)When heated to 220.oC, BeC2O4•3H2O (s) dehydrates completely as represented below. BeC2O4•3H2O (s) BeC2O4(s) + 3 H2O(g) If 3.21 g of BeC2O4•3H2O (s) is heated to 220.oC calculate the mass of BeC2O4(s) formed.