2. Balance the following equation (find what number coefficient X is): NH3 (g) + O2 (g) --> NO (g) + XH2O (g).
2 3 4 5 6
3. The empirical formula of a compound is C10H20 with a molar mass of 284 grams, find the molecular weight.
C20H40 C10H20 C5H10 C4H8 CH4
4. There are two beakers sitting on a table. One contains 56.20 grams of water. The other contains hydrochloric acid (HCl). The number of atoms of hydrogen in the HCl equals the number of total atoms in the beaker full of water. How many grams of HCl are in the second beaker?
341.4 grams 142.4 g 938.1 g 53.29 g None of these
5. How many carbon molecules are present in 5.0 grams of glucose? (C6H12O6)
1.0 * 10^22 5.1 * 10^22 1.0 * 10^23 6 None
6. A chemistry student was performing an experiment involving the following reaction: C3H8 (g) + O2 (g) --> CO2 (g) + H2O (g), balancing it with the coefficients 1, 5, 2, and 4 respectively. The oxygen was in excess. He used 20.18 grams of C3H8. When he measured the amount of CO2 produced, he was astounded to find that 46.22 grams were produced, 5.88 grams more than the theoretical yield of 40.34. What went wrong? Hint: Look at the formula
C3H8's coefficient should be 3, not 1 CO2's coefficient should be 3, not 2 O2's coefficient should be 3, not 5 Water's coefficient should be 3, not 4 None of these
7. How many moles in 20 g of water?
1.11 20 18 1.1 42
8. 6.02x1023 is....
a random number Avogadro's number stoichiometry percent yield None of these
9. Hydrochloric acid reacts with calcium carbonate yielding calcium chloride, water, and carbon dioxide. How many moles of calcium carbonate would be necessary to react with 8 moles of HCl?
1 2 3 4 5
10. How many grams is 0.25 moles of table salt (NaCl?)
58.44 grams 14.61 grams 14.6 grams 58 grams 15 grams
11. There are 2.34 moles of substance A3 combined with 2.77 moles of substance B. Assume that the reaction goes to completion. After the reaction is complete, AB is reacted with substance C2. The reaction creates CB and A. If C2 was in excess during the second reaction, then how many moles of CB were produced?
2.43 moles 3.82 moles 4.38 moles 7.02 moles None of these
12. What is the % mass of carbon in carbon dioxide?
44% 25% 27% 63% 50%
13. What is the mass percent of oxygen in H2SO4 (sulfuric acid)?
0 1% 2.04% 32.70% 65.26%
14. When 2 moles of propane (C3H8, MW = 44 grams) is combusted with oxygen gas, how many grams of CO2 (MW: 44 grams) are produced?
88 44 3 132 264
15. If 11 grams in a reaction was obtained, and you had a theoretical yield of 14 grams, what is your % yield?
0.79% 79% 11% 14% 12%
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