2) How many oxygen atoms are there in 1.55 ng of Ca3(PO4)2? a) 3.01 x b) 1.20 x c) 3.01 x d) 1.21 x e) 2.

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1 Name: Directions: Answer the following questions based on your review of Chapters 1-4 in your text along with your education in Chemistry Level I. You must defend your answers in order to receive credit. Question #1-4: Phosphoric acid can be prepared by reaction of sulfuric acid with phosphate rock according to the equation: Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4 1) What is the molar mass of Ca3(PO4)2? a) g/mol b) g/mol c) g/mol d) g/mol e) g/mol 2) How many oxygen atoms are there in 1.55 ng of Ca3(PO4)2? a) 3.01 x b) 1.20 x c) 3.01 x d) 1.21 x e) 2.41 x ) Suppose the reaction is carried out starting with 103 g of Ca3(PO4)2 and 75.0 g of H2SO4. Which substance is the limiting reactant? a) Ca3(PO4)2 b) H2SO4 c) CaSO4 d) H3PO4 e) none of these 4) Gallium consists of two isotopes of masses amu and amu with abundances of 60.16% and 39.84%, respectively. What is the average atomic mass of gallium? a) b) c) d) e)

2 5) A substance contains 35.0 g nitrogen, 5.05 g hydrogen, and 60.0 g of oxygen. How many grams of hydrogen are there in a 185-g sample of the substance? a) 9.34 g b) 18.7 g c) 10.6 g d) 5.05 g e) 36.6 g 6) Suppose the reaction Ca3(PO4)2 + 3H2SO4 3CaSO4 + 2H3PO4 is carried out starting with 103 g of Ca3(PO4)2 and 75.0 g of H2SO4. How much phosphoric acid will be produced? a) 74.9 g b) 50.0 g c) 112 g d) 32.5 g e) 97.6 g 7) A chloride of rhenium contains 63.6% rhenium. What is the formula of this compound? a) ReCl b) ReCl3 c) ReCl5 d) ReCl7 e) Re2Cl3 8) A titration was performed to find the concentration of hydrochloric acid with the following results Trial Molarity ± ± ± 0.01 The actual concentration of the acid was determined to be M; the result of the titration are: a) both accurate and precise. b) accurate but imprecise. c) precise but inaccurate. d) both inaccurate and imprecise. e) Accuracy and precision are impossible to determine with the information given. 2

3 9) Which of the following pairs of compounds can be used to illustrate the Law of Multiple Proportions? a) NH4 and NH4Cl b) ZnO2 and ZnCl2 c) H2O and HCl d) NO and NO2 e) CH4 and CO2 10) Many classic experiments have given us indirect evidence of the nature of an atom. Which of the experiments listed below did not give the results described? a) The Rutherford experiment proved the Thomson plum-pudding model of the atom to be essentially correct. b) The Rutherford experiment was useful in determining the nuclear charge on the atom. c) Millikan s oil-drop experiment showed that the charge on any particle was a simple multiple of the charge of the electron. d) The electric discharge tube proved that electrons have a negative charge ) 20Ca 2+ has a) 20 protons, 20 neutrons, and 18 electrons. b) 22 protons, 20 neutrons, and 20 electrons. c) 20 protons, 22 neutrons, and 18 electrons. d) 22 protons, 18 neutrons, and 18 electrons. e) 20 protons, 20 neutrons, and 22 electrons. 12) An ion is formed a) by either adding or subtracting protons from the atom. b) by either adding or subtracting electrons from the atom. c) by either adding or subtracting neutrons from the atom. d) All of these are true. e) Two of these are true. 13) A 20.0 g sample of HF is dissolved in water to give 2.0 x 10 2 ml of solution. The concentration of the solution is: a) 1.0 M b) 3.0 M c) 0.10 M d) 5.0 M e) 10.0 M 14) Which of the following aqueous solutions contain the greatest number of ions? a) ml of 0.10 M NaCl b) ml of 0.10 M CaCl2 c) ml of 0.10 M FeCl3 d) ml of 0.10 M KBr e) ml of 0.10 M sucrose 3

4 15) The net ionic equation for the reaction of calcium bromide and sodium phosphate contains which of the following species? a) Ca 2+ (aq) b) PO4 3- (aq) c) 2Ca3(PO4)2(s) d) 6NaBr(aq) e) 3Ca 2+ (aq) 16) Aqueous solutions of sodium sulfide and copper(ii) chloride are mixed together. Which statement is correct? a) Both NaCl and CuS precipitate from solution. b) No precipitate forms. c) CuS will precipitate from solution. d) NaCl will precipitate from solution. e) No reaction will occur. 17) What mass of NaOH is required to react exactly with 25.0 ml of 1.2 M H2SO4? a) 1.2 g b) 1.8 g c) 2.4 g d) 3.5 g e) None of these. 18) In which of the following does nitrogen have an oxidation number of +4? a) Nitric acid b) Nitrogen dioxide c) Dinitrogen oxide d) Ammonium chloride e) Sodium nitrite 19) Which of the following statements is not true? a) When a metal reacts with a nonmetal, an ionic compound is formed. b) A metal-nonmetal reaction can always be an oxidation-reduction reaction. c) Two nonmetals can undergo an oxidation-reduction. d) When two nonmetals react, the compound formed is ionic. e) A metal-nonmetal reaction involves electron transfer. 20) In the reaction Cs(s) + Cl2(g) CsCl(s), Cl2 is a) the reducing agent. b) the oxidizing agent. c) oxidized. d) the electron donor. e) Two of these. 4

5 21) The SO2 present in air is mainly responsible for the acid rain phenomenon. Its concentration can be determined by titrating against a standard permanganate solution as follows: 5SO2 + 2MnO H2O 5SO Mn H + Calculate the number of grams of sulfur dioxide in a sample of air if 7.37 ml of M KMnO4 solution required for the titration. a) 9.44 x 10-3 g b) 2.01 x 10-4 g c) 10 g d) 1.05 g e) 1.23 x 10-2 g 22) Oxides of copper include CuO and Cu2O. You heat 1.51 g of one of these copper oxides in the absence of air and obtain 1.21 g of Cu. True or false: You must have had CuO. 23) You heat g of a mixture of Fe3O4 and FeO to form g Fe2O3. The mass percent of FeO originally in the mixture was: (Hint: Assume all the Fe 2+ is converted to Fe 3+.) a) 12.1% b) 28.7% c) 71.3% d) 87.9% e) none of these 24) You heat g of a mixture of Fe3O4 and FeO to form g Fe2O3. The mass of oxygen reacted is a) g. b) g. c) 1.00 g. d) cannot be determined e) none of these 25) A mixture of KCl and KNO3 is 44.20% potassium by mass. The percent of KCl in the mixture is closest to (Hint: remember the conversion that one percent equals one gram.) a) 40% b) 50% c) 60% d) 70% e) 80% 5

6 ANSWERS 1) A 2) E 3) B 4) D 5) A 6) B 7) B 8) C 9) D 10) A 11) A 12) B 14) C 15) E 16) C 17) C 18) B 19) D 20) B 21) A 22) TRUE 23) B 24) A 25) A 13) D 6