Questions 1-5 Refer to the Following Solid Compounds

Name:______Date:______Period:____

WS Stoichiometry & Solutions

SECTION I: MULTIPLE CHOICE (NO CALCULATOR)

Questions 1-5 refer to the following solid compounds.

(A) Pb(NO ) (B) CuSO (C) KMnO (D) KCl (E) Fe(OH) 3 2 4 4 2

___1. Is purple in aqueous solution ___2. Is a common strong oxidizer in aqueous solution

___3. Forms a white precipitate when mixed with AgNO3. ___4. Is blue in aqueous solution ___5. Is insoluble in water

___6. What number of moles of O2 is needed to produce 14.2 grams of P4O10 from P ? (Molecular weight P4O10 = 284) (A) 0.0500 mole (B) 0.0625 mole (C) 0.125 mole (D) 0.250 mole (E) 0.500 mole

___7. What is the maximum number of moles of Al2O3 that can be produced by the reaction of 0.40 mol of Al with 0.40 mol of O2 ? (A) 0.10 mol (B) 0.20 mol (C) 0.27 mol (D) 0.33 mol (E) 0.40 mol ___8. The simplest formula for an oxide of nitrogen that is 36.8 percent nitrogen by weight is

(A) N2O (B) NO

(D) N2O3

(E) N2O5

+ – 2+ 10 H + 4 Zn + 2 NO3  4 Zn + N2O + 5 H2O − ___9. In the reaction represented above, the number of NO3 ions that react must be equal to which of the following? (A) ten times the number of H+ ions that are consumed (B) one half the number of Zn atoms that are consumed (C) four times the number of Zn2+ ions that are produced

(D) one-half the number of N2O molecules that are produced

___10. 10 HI + 2 KMnO4 + 3 H2SO4  5 I2 + 2 MnSO4 + K2SO4 + 8 H2O According to the balanced equation above, how many moles of HI would be necessary to produce 2.5 mol of I2, starting with 4.0 mol of KMnO4 and 3.0 mol of H2SO4? (A) 20 (B) 10 (C) 8.0 (D) 5.0 (E) 2.5 ___11. A measured mass of an unreactive metal was dropped into a small graduated cylinder half filled with water. The following measurements were made. Mass of metal = 19.611 grams Volume of water before addition of metal = 12.4 milliliters Volume of water after addition of metal = 14.9 milliliters The density of the metal should be reported as (A) 7.8444 grams per mL (B) 7.844 grams per mL (C) 7.84 grams per mL (D) 7.8 grams per mL (E) 8 grams per mL

___12. Which of the following does NOT behave as an electrolyte when it is dissolved in water?

(A) CH3OH

(B) K2CO3

(E) Sodium acetate, CH3COONa (or NaC2H3O2)

___13. A 1.0 liter sample of an aqueous solution contains 0.10 mol of NaCl and 0.10 mol of CaCl2. What is the minimum number of moles of AgNO3 that must be added to the solution in order to precipitate all of the Cl¯ as AgCl(s) ? (Assume that AgCl is insoluble.) (A) 0.10 mol (B) 0.20 mol (C) 0.30 mol (D) 0.40 mol (E) 0.60 mol

___14. A yellow precipitate forms when 0.5 M NaI(aq) is added to a 0.5 M solution of which of the following ions? (A) Pb2+(aq) (B) Zn2+(aq) 2 (C) CrO4 ¯(aq) 2 (D) SO4 ¯(aq) (E) OH¯(aq) ___15. What is the final concentration of barium ions, [Ba2+], in solution when 100. mL of 0.10 M BaCl2(aq) is mixed with 100. mL of 0.050 M H2SO4(aq)? (A) 0.00 M (B) 0.012 M (C) 0.025 M (D) 0.075 M (E) 0.10 M

___16. When 100 mL of 1.0 M Na3PO4 is mixed with 100 mL of 1.0 M AgNO3, a yellow precipitate forms and [Ag+] becomes negligibly small. Which of the following is a correct listing of the ions remaining in solution in order of increasing concentration?

3 + (A) [PO4 ¯] < [NO3¯] < [Na ] 3 + (B) [PO4 ¯] < [Na ] < [NO3¯] 3 + (C) [NO3¯] < [PO4 ¯] < [Na ] + 3 (D) [Na ] < [NO3¯] < [PO4 ¯] + 3 (E) [Na ] < [PO4 ¯] < [NO3¯] SECTION II: FREE RESPONSE Calculator Permitted

CLEARLY SHOW THE METHODS USED AND STEPS INVOLVED IN YOUR ANSWERS. It is to your advantage to do this, because you may earn partial credit if you do and little or no credit if you do not. Attention should be paid to significant figures.

2 Fe(s) + O (g)  Fe O (s) ∆H ˚ = –824 kJ∙mol–1 2 2 3 f

1. Iron reacts with oxygen to produce iron(III) oxide as represented above. A 75.0 g sample of Fe(s) is mixed with 11.5 L of O (g) at 2.66 atm and 298 K. 2 (a)Calculate the number of moles of each of the following before the reaction occurs. (i) Fe(s)

(ii) O (g) 2

(b) Identify the limiting reactant when the mixture is heated to produce Fe O . 2 3 Support your answer with calculations.

(c)Calculate the number of moles of Fe O produced when the reaction proceeds to completion. 2 3 2. Answer the following questions that relate to the analysis of chemical compounds. (a)A compound containing the elements C, H, N, and O is analyzed. When a 1.2359 g sample is burned in excess oxygen, 2.241 g of CO2(g) is formed. The combustion analysis also showed that the sample contained 0.0648 g of H. (i) Determine the mass, in grams, of C in the 1.2359 g sample of the compound.

(ii) When the compound is analyzed for N content only, the mass percent of N is found to be 28.84 percent. Determine the mass, in grams, of N in the original 1.2359 g sample of the compound.

(iii) Determine the mass, in grams, of O in the original 1.2359 g sample of the compound.

(iv) Determine the empirical formula of the compound. (b) A different compound, which has the empirical formula CH2Br, has a vapor density of 6.00 g L–1 at 375 K and 0.983 atm. Using these data, determine the following. (i) The molar mass of the compound

(ii) The molecular formula of the compound Your responses to these questions will be graded on the basis of the accuracy and relevance of the information cited. Explanations should be clear and well organized. Examples and equations may be included in your responses where appropriate. Specific answers are preferable to broad, diffuse responses. 3. The identity of an unknown solid is to be determined. The compound is one of the seven salts in the following table.