Sample Questions - Chapter 2

Chemical Formulas and Composition StoichiometryExamples ofMultiple Choice Questions

1.The formula weight of the compound, Al2(SO4)318H2O is: (a) 394.4 g (b) 666.4 g (c) 110,900 g (d) 466.8 g (e) 561.2 g 2.The weight of a millimole of (NH4)2HPO4 is: (a) 132 g (b) 114 g (c) 1.14 x 10-3 g (d) 0.132 g (e) 6.02 x 1020 g 3.How many moles of alanine, C3H7NO2, are there in 159 g of alanine? (a) 1.42 x 104 (b) 1.78 (c) 0.992 (d) 0.560 (e) 3.31 4.How many atoms are in one mole of CH3OH? (a) 6 (b) 6.0 x 1023 (c) 12.0 x 1023 (d) 3.6 x 1024 (e) 3 5.The mass in grams of 2.6 x 1022 chlorine atoms is: (a) 4.4 (b) 11 (c) 0.76 (d) 1.5 (e) 3.2 6.How many aluminum atoms are there in 3.50 grams of Al2O3? (a) 4.13 x 1022 (b) 4.90 x 1022 (c) 2.07 x 1022 (d) 1.68 x 1022 (e) 2.45 x 1022 7.Which one of the samples contains the most atoms? (a) 1 mol of CO2(g) (b) 1 mol of UF6(g) (c) 1 mol of CH3COCH3(l) (d) 1 mol of He(g) (e) all contain the same number of atoms 8.Which one of the samples contains the most molecules? (a) 1 mol of CO2(g) (b) 1 mol of UF6(g) (c) 1 mol of CH3COCH3(l) (d) 1 mol of He(g) (e) all contain the same number of molecules 9.Which one of the samples has the largest mass? (a) 1 mol of CO2(g) (b) 1 mol of UF6(g) (c) 1 mol of CH3COCH3(l) (d) 1 mol of He(g) (e) all have the same mass 10.Which of the following statements is(are) FALSE? 1. The percent by mass of each element in a compound depends on the amount of the compound. 2. The mass of each element in a compound depends on the amount of the compound. 3. The percent by mass of each element in a compound depends on the amount of element present in the compound.(a) 2 and 3 (b) 1 only (c) 1 and 2 (d) 1, 2 and 3 (e) another combination 11.Guanidin, HNC(NH2)2, is a fertilizer. To three significant figures, what is the percent by mass of nitrogen in the fertilizer? (a) 45.2% (b) 49.4% (c) 54.8% (d) 65.1% (e) 71.1% 12.Calculate the percent, by weight, of carbon in 154 g of C4H8O3? (a) 46% (b) 31% (c) 72% (d) 27% (e) 55% 13.Analysis of a sample of a covalent compound showed that it contained 14.4% hydrogen and 85.6% carbon by mass. What is the empirical formula for the compound? (a) CH (b) CH2 (c) CH3 (d) C2H3 (e) none of these 14.An oxide of lead contains 90.65% Pb, by weight. The empirical formula is: (a) Pb (b) PbO (c) Pb3O4 (d) Pb2O3 (e) PbO2 15.A 0.500 g sample of a compound containing only antimony and oxygen was found to contain 0.418 g of antimony and 0.082 g of oxygen. What is the simplest formula for the compound? (a) SbO (b) SbO2 (c) Sb3O4 (d) Sb2O5 (e) Sb2O3 16.A compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen. A 0.320 mole sample of this compound weighs 28.8 g. The molecular formula of this compound is: (a) C2H4O2 (b) C3H6O3 (c) C2H4O (d) CH2O (e) C4H7O2 17.What mass of cerussite, PbCO3, would contain 35.0 grams of lead? (a) 27.1 g (b) 45.1 g (c) 42.4 g (d) 35.6 g (e) 51.7 g

Answers:

1. (b) 2. (d) 3. (b) 4. (d) 5. (d) 6. (a) 7. (c) 8. (e) 9. (b) 10. (b) 11. (e) 12. (a) 13. (b) 14. (c) 15. (e) 16. (b) 17. (b)

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