CHM 2045 Fall 2022 Exam 1 (Harris, Korolev, Lopez, Song, Sumner) - Chemistry Past Paper PDF

**[Form Code A] NAME\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **[CHM 2045 Fall 2022 Exam 1 (Harris, Korolev, Lopez, Song, Sumner) (Chapters 1, 2, 3, 4, 5)]** **Instructions: On your Scantron form, [enter and bubble] your [name, UFID, and Form Code] (see above)....

**[Form Code A] NAME\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_** **[CHM 2045 Fall 2022 Exam 1 (Harris, Korolev, Lopez, Song, Sumner) (Chapters 1, 2, 3, 4, 5)]** **Instructions: On your Scantron form, [enter and bubble] your [name, UFID, and Form Code] (see above). Turn in only your Scantron. You may keep your exam sheet and any other papers. Check bubbling carefully: [bubbling errors are non-negotiable.] As on all graded events, the Honor Code applies.** **Questions 1-10 are worth 5 points each. Questions 11-25 are worth 10 points each.** **1. How many of the following quantities have five significant figures?** **a. 0.1055 g  b. 53,080 mL  c. 0.0020 L  d. 0.0000081200 cm^3^  e. 0.00004813 m ** **(1) one (2) two (3) three (4) four (5) five** **2. Bromine has two naturally-occurring isotopes. ^79^Br has a mass of 78.9 amu and accounts for 50.3% of bromine atoms. What is the mass of an atom of the second bromine isotope? ** **(1) 77.9 amu    (2)  80.0 amu    (3)  80.1 amu (4) 80.9 amu    (5)  88.9 amu ** **3. Classify each substance as a pure substance or a mixture. If it is a pure substance, classify it as an element or a compound. If it is a mixture, classify it as homogeneous or heterogeneous. ** **        a. sweat    b. carbon dioxide    c. aluminum     ** **(1) a: mixture, heterogeneous; b: pure substance, compound; c: pure substance, element  ** **(2) a: mixture, homogeneous; b: pure substance, compound; c: pure substance, element  ** **(3) a: mixture, homogeneous; b: pure substance, compound; c: pure substance, compound** **(4) a: mixture, homogeneous; b: mixture, heterogeneous; c: pure substance, element** **(5) a: mixture, heterogeneous; b: mixture, heterogeneous; c: pure substance, compound** **4. Which of the following formulas and names are correct? ** **I: CoCl~2~ -- cobalt chloride  II: P~2~I~4~ -- diphosphorus tetraiodide III: H~2~PO~3~ -- phosphoric acid** **(1) Only I (2) Only II (3) I and II (4) II and III (5) I and III** **5. An isotope of an element contains 82 protons and 122 neutrons. What is the symbol for the isotope? ** **(1) ^204^~82~Pb   (2) ^122^~82~Pb   (3) ^122^~40~Zr    (4) ^204^~40~Zr    (5) ^82^~40~Zr ** **6. How many atoms of oxygen are contained in 5.0 grams of Ca~3~(PO~4~)~2~? ** **(1) 9.7x10^21^ (2) 2.2x10^22^ (3) 3.9x10^22^ (4) 7.8x10^22^ (5) 8.9x10^22^ ** ** ** **7. Balance the following equation using the smallest possible whole number coefficients: ** **Ca~3~(PO~4~)~2~ + SiO~2~ + C → CaSiO~3~ + P~4~ + CO.** **What is the sum of the coefficients (don't forget to add any implied coefficients of "1")? ** **(1) 12 (2) 19 (3) 26 (4) 35 (5) 45** **8. Which of the following is the net ionic equation for the reaction between Ca(OH)~2~ and FeSO~4~? ** **(1) Ca(OH)~2~ + FeSO~4~ → CaSO~4~ + Fe(OH)~2~** **(2) Ca^2+^ + SO~4~^2−^ → CaSO~4~** **(3) Ca(OH)~2~ + FeSO~4~ → Ca^2+^ + 2OH^−^ + Fe^2+^ + SO~4~^2−^** **(4) 2OH^−^ + Fe^2+^ → Fe(OH)~2~** **(5) Ca^2+^ + 2OH^−^ + Fe^2+^ + SO~4~^2−^ → CaSO~4~ + Fe(OH)~2~** **9. Identify the oxidizing agent in the following equation:** **2 NaMnO~4~ (aq) + 3 Na~2~C~2~O~4~(aq) + 4 NaOH (aq) → 2 MnO~2~(s) + 6 Na~2~CO~3~(aq) + 2 H~2~O(l)** **(1) NaMnO~4~ (2) Na~2~C~2~O~4~ (3) NaOH (4) MnO~2~ (5) Na~2~CO~3~** **10. Which of the following has the correct oxidation state listed for Mn?** **(1) +1 in KMnO~4~ (2) +2 in Mn~2~O~3~ (3) +4 in Mn~3~O~4~ (4) +6 in Mn~2~O~7~ (5) +6 in K~2~MnO~4~** **11. The volume of one bacterial cell is 3.25 µm^3^.  What is the volume of 10^6^ bacterial cells in liters?  ** **(1) 3.25x10^-9^ L (2) 3.25x10^-6^ L (3) 3.25x10^-3^ L (4) 3.25x10^3^ L (5) 3.25x10^6^ L** **12.  A NASA spacecraft measures the rate, R, at which atmospheric pressure on Mars decreases with altitude as R = 0.0406 kPa km^-1^. Convert R to mJ m^-4^.  ** **Possibly useful information: 1 Pa = kg m^-1^ s^-2^ 1 J = 1 Pa m^3^ ** **(1) 4.06x10^-8^ J m^-4^ (2) 4.06x10^-5^ J m^-4^ (3) 0.0406 J m^-4^ (4) 40.6 J m^-4^ (5) 4.06x10^4^ J m^-4^** **13. Chalcocite is a commonly mined copper ore that contains copper (I) sulfide. If a chalcocite ore contains 75.0% copper (I) sulfide by mass, how many kilograms of copper can be extracted from 80.0 kg of chalcocite?**   **(1) 24.0 kg** **(2) 39.9 kg** **(3) 47.9 kg** **(4) 60.0 kg** **(5) 63.9 kg**   **14. A sample of a hydrocarbon produced 3.14 grams of CO~2~ and 1.28 grams of H~2~O during combustion analysis. If the hydrocarbon has a molar mass between 50 and 60 g/mol, what is its molecular formula?  ** **(1) C~3~H~6~ (2) C~3~H~8~ (3) C~4~H~4~ (4) C~4~H~8~ (5) C~4~H~10~  ** **15. Consider the reaction: 3 F~2~(g) + N~2~(g) → 2 NF~3~(g). When 12.0 moles of F~2~ and 7.0 moles of N~2~ react as completely as possible, how many moles of the excess reactant remain?  ** **(1) 3.0 moles (2) 4.0 moles (3) 5.0 moles (4) 6.0 moles (5) 7.0 moles** **16. Nitrogen dioxide can be formed through the following two-step process: ** **Step 1: NO(g) + O~2~(g) → NO~3~(g)** **Step 2: NO~3~(g) + NO(g) → 2 NO~2~(g) ** **If the percent yield of the first step is 35.0% and the percent yield of the second step is 40.0%, how many grams of NO~2~ can be formed from 10.0 g of NO? ** **(3) 2.15 g (2) 2.80 g (3) 4.29 g (4) 11.5 g (5) 23.0 g** **17. What volume (mL) of 1.0 M magnesium chloride solution must be added to an excess volume of aqueous silver nitrate solution to be able to produce 20.0 g of precipitate? \ (1)  20 mL (2) 70 mL (3)  140 mL (4)  210 mL (5)  280 mL** **18. What volume (mL) of aqueous 0.75 M calcium nitrate solution must be diluted with pure water to produce 1.00 L of a solution with 0.45 M nitrate ion?\ (1) 100 mL (2) 167 mL (3) 300 mL (4) 500 mL (5) 600 mL** **19. If 50.0 mL of a standard 0.200 M NaOH solution is required to neutralize 10.0 mL of H~2~SO~4~, what is the molarity of the acid solution?** **(1) 0.100 M (2) 0.200 M (4) 0.500 M (4) 1.00 M (5) 2.00 M** **20. Which of the following equations is/are properly classified as precipitation, reduction/oxidation, and/or Bronsted-Lowry acid/base reaction?** **I: 2 AgNO~3~(aq) + Cu(s) → Cu(NO~3~)~2~(aq) + 2 Ag(s) is reduction/oxidation, but isn't precipitation** **II: 3 NaOH(aq) + AlCl~3~(aq) → 3 NaCl(aq) + Al(OH)~3~(s) is precipitation, but isn't acid/base** **III: H~2~SO~4~(aq) + Ba(OH)~2~(aq) → 2 H~2~O(l) + BaSO~4~(s) is acid/base, but isn't reduction/oxidation** **(1) Only I (2) Only II (3) I and III (4) II and III (5) I, II, and III** **21. What is the density of a sample of argon gas at 55.0°C and 765 mmHg?** **(1) 2.99 g/L (2) 1.13 x 10^3^ g/L (3) 1.49 g/L (4) 8.91 /L (5) 6.45 g/L** **22. A tightly sealed 4.0-L flask contains 884 mmHg of N~2~ at 94.0°C. The flask is cooled until the pressure is reduced to 442 mmHg. What is the temperature of the gas?** **(1) ‒ 47.0°C (2) 47.0°C (3) ‒ 89.5°C (4) 184°C (5) 188°C** **23. A balloon is filled with equal molar amounts of H~2~ and N~2~, but both gases leak through pores in the balloon. When 45% of the H~2~ leaks out, what % of N~2~ remains in the balloon?** **(1) 12% (2) 17% (3) 55% (4) 83% (5) 88%** **24. A sample of XeO~4~ was fully decomposed into its elements, and the resulting gas was collected over water at 29°C. If the total pressure of the collected gas was 750 torr, and the vapor pressure of water at 29°C is 30.0 torr, what was the partial pressure of O~2~ gas in the flask?** **(1) 360 torr (2) 375 torr (3) 480 torr (4) 500 torr (5) 720 torr** **25. In a closed 1.00 L flask, 2.60 atm of CO reacts with 5.80 atm of O~2~ according to the equation below. Assuming that the temperature remains constant, what is the final pressure in the flask?** **2 CO(g) + O~2~(g) → 2 CO~2~(g)** **(1) 1.30 atm (2) 2.60 atm (3) 4.50 atm (4) 5.70 atm (5) 7.10 atm**