CHE 105 14 September 1995 MID-TERM EXAMINATION I
University of Kentucky Department of Chemistry 1. All atoms of the same element
A. have the same number of neutrons in the nucleus. B. have the same number of electrons in the nucleus. C. have the same number of protons in the nucleus. D. have exactly the same mass.
2. The empirical formula for the compound C6H12O6 isA. C12H24O12 B. C3H6O3 C. C2H4O2 D. CH2O
3. Lime (CaO) and CO2 are produced by heating limestone (CaCO3) to a high temperature. Calculate the amount of CaO that will be produced from 7.19 tons of CaCO3, assuming the process is 91.5% efficient.A. 7.38 kg B. 3.69 tons C. 147 pounds D. 1.47 x 103 tons
4. Which of the following lists contain the correct formulas for iron(III) chloride, copper(I) oxide, ammonium nitrate, and xenon tetrafluoride?A. FeCl2, Cu2O, NH4NO3, ZnF4 B. Fe3Cl, CuO2, NH4NO2, ZnF4 C. FeCl3, Cu2O, NH4NO3, XeF4 D. FeCl3, CuO, NH4NO2, XeF4
5. The balanced equation for the combustion of C3H8 isA. C3H8 = 3 C + 8 H B. C3H8 + O2 = CO2 + H2O C. 2 C3H8 + 5 O2 = 6 CO + 4 H2O D. C3H8 + 5 O2 = 3 CO2 + 4 H2O
6. It is very difficult to separate chemically isotopes of an element from each other becauseA. isotopes of an element contain the same number of neutrons. B. isotopes of an element contain the same number of protons. C. isotopes of an element have the same atomic mass. D. isotopes of an element contain the same number of electrons.
7. Epsom salt is a hydrate of magnesium sulfate. A sample of Epsom salt is found to contain 9.86% magnesium, 13.0% sulfur, 5.72% hydrogen, and 71.4% oxygen. Select the correct formula for Epsom salt.A. MgSO3.6 H2O B. MgSO4.7 H2O C. MgSO4.5 H2O D. MnSO4.6 H2O
8. Which of the following lists contain the correct formulas for the permanganate, dichromate, sulfite, and chlorate ions?A. MnO4-, CrO42-, SO42-, Cl- B. MnO4-, Cr2O72-, SO32-, ClO3- C. MnO42-, Cr2O32-, SO42-, ClO4- D. MnO4-, Cr2O72-, SO32-, OCl-
9. Determine the limiting reagent and the number of moles of N2 formed in the following balanced reaction.3 CuO + 2 NH3 = N2 + 3 H2O + 3 Cu Reacted: 1.5 moles 1.5 moles
A. CuO, 0.50 moles B. CuO, 0.33 moles C. NH3, 0.75 moles D. NH3, 0.50 moles
10. Indicate whether the following statements correctly describe an ionic substance, a molecular substance, or both ionic and molecular substances.1. The solid does not conduct electrical current. 2. In general, the substances are hard crystalline solids with high melting points. 3. Conducts an electric current in the liquid state.
A. ionic, ionic, molecular B. molecular, molecular, both C. molecular, ionic, ionic D. both, ionic, ionic
11. The species containing 17 protons, 18 neutrons and 18 electrons is correctly represented by which of the following symbols?A. 1817Cl- B. 3517Cl- C. 3518Ar D. 3517Br-
12. Consider the following balanced equationN2 + 3 H2 = 2 NH3
How many grams of NH3 is produced if 10.0 g of N2 is reacted with 10.0 g of H2?
A. 12.2 g B. 56.3 g C. 6.10 g D. 20.0 g
13. The total number of atoms in 9.0 g of water isA. 3.0 x 1023 B. 8.3 x 10-25 C. 9.0 x 1023 D. 1.0 x 1024
14. The number of neutrons, protons and electrons in 3919K+ are
A. 20, 19, 19 B. 39, 19, 19 C. 20, 19, 18 D. 39, 19, 18
15. The reaction 3 Ca(OH)2 + 2 H3PO4 = Ca3(PO4)2 + 6 H2O is an example of a(n) _______________ reaction.A. combustion B. neutralization C. electrophilic substitution D. ionic exchange
16. Which of the following is an ionic compound?A. ClO4- B. Au C. CCl4 D. Na2Cr2O7
17. Silicon carbide is an extremely hard substance, almost as hard as diamond. A pure sample of 0.531 g of it was analyzed by combustion in excess oxygen to produce 0.583 g CO2. If the remainder of the (pure) substance was silicon, what is the empirical formula for silicon carbide?
A. SiC B. SiC2 C. Si7C3 D. Cannot determine with the information given.
18. Name the following compound and indicate whether it is ionic or molecular. P2I4A. phosphorus tetraiodide; molecular B. diphosphorus tetraiodide; molecular C. diphosphorus iodide; ionic D. phosphorus iodide; ionic
19. Magnesium oxide is produced by the combustion of magnesium. Assuming an excess of oxygen, what is the theoretical yield of magnesium oxide that can be produced by burning 2.0 g magnesium?A. 3.3 g B. 4.6 g C. 6.6 g D. 4.0 g
20. Which of the following are true statements?1. The masses of the proton and neutron are nearly the same. 2. Electrons make up most of the mass of an atom. 3. Atoms are indivisible. 4. The charges of the electron and proton are exactly equal but opposite in sign.
A. 1 and 2 B. 1 and 3 C. 1 and 4 D. 2 and 3
21. Poseidon, while bored, began counting the number of water molecules in the ocean. He (being a god) could count 100 molecules per second. After counting for 3 years (9.46 x 107 seconds) he was thirsty and drank the water he had counted. How many mL of water did he drink? (The density of water is 1.00 g/mL)A. 2.83 x 10-13 mL B. 1.70 x 1011 mL C. 1.57 x 10-14 mL D. More information must be provided.
22. The correct formula for iron(III) phosphate isA. Fe3PO4 B. FePO4 C. Fe2(PO4)3 D. Fe3PO3
23. When the reactionK4Fe(CN)6 + H2SO4 + H2O = K2SO4 + FeSO4 + (NH4)2SO4 + CO
is balanced so that the coefficient of K4Fe(CN)6 is one, the coefficients of H2O and (NH4)2SO4, respectively, will be
A. 6, 3 B. 3, 6 C. 6, 1 D. 4, 3
24. How many oxygen atoms are in a 48.0 g sample of hydrogen peroxide, H2O2?A. 6.02 x 1023 B. 8.50 x 1023 C. 1.70 x 1024 D. 1.70033 x 1024
25. Determine the empirical formula of a compound that is 25.9% nitrogen and 74.1% oxygen by mass.A. N4O10 B. N4O6 C. N2O3 D. N2O5