Exam 1 Form B Key fall 07CHEM103A Dr. Keller

Exam 1 Form B Key fall 07CHEM103A Dr. Keller - Chemistry...

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Unformatted text preview: Chemistry 103A Exam 1 Form B Answer Key 1. (2) A 1.00 mol sample of the molecular compound sulfur dioxide (SO2) (a) is 64.0 g of SO2 (b) is 6.02 x 1023 SO2 molecules (c) has the same number of molecules as 16.0 g of methane (CH4) (d) has 1.81 x 1024 atoms (e) all of these 2. (2) The weight of 377 cm3 of pure water is (a) 385 g (b) 0.377 kg (c) 0.377 mg (d) 364 g (e) 0.0377 Mg 3. (2) In the original metric system the gram was defined to be (a) 0.001 kg (b) 2.205 x 10-3 lb (c) 10-3 L of water (d) the weight of 1 cm3 of water (e) 1 cm3 of water 4. (2) On problem 8 of the first problem set 36 students chose a hair growth rate of 4 x 10-14 Gm/fs. Convert this to m/s. (a) 4 x 1016 m/s (b) 4 x 1021 m/s (c) 4 x 1013 m/s (d) 4 x 107 m/s (e) 4 x 1010 m/s 5. (2) Which statement about balanced equations is incorrect? (a) the total weight on each side is the same (b) the number of atoms on each side is the same (c) the number of molecules on each side is the same (d) conservation of matter is obeyed in a balanced equation (e) the same formula never appears on both sides of the equation 6. (2) The balanced equation for the reaction of aluminum with bromine is 2 Al + 3 Br2 Al2Br6. How many grams of bromine are needed to form 2.43 mol of Al2Br6? (a) 239.5 g (b) 159.7 g (c) 479 g (d) 582.5 g (e) 1165 g 7. (2) The balanced equation for the reaction of aluminum with bromine is 2 Al + 3 Br2 Al2Br6. How many moles of aluminum are needed to form 2.43 mol of Al2Br6? (a) 4.86 mol (b) 1.22 mol (c) 1.62 mol (d) 2.43 mol (e) 7.29 mol 8. (2) If Avogadros number were defined as the number of carbon atoms in 12.0 centigrams of carbon, it would have the value (a) 6.022 x 1020 (b) 6.022 x 1021 (c) 6.022 x 1022 (d) 6.022 x 1023 (e) 6.022 x 1025 9. (2) The number of atoms in one molecule of ethene C2H4 (a) 6.022 x 1023 (b) 6 (c) 3.61 x 1024 (d) 7.227 x 1024 (e) 7.528 x 1022 10. (2) The number of atoms in one mole of ethene C2H4 (a) 6.022 x 1023 (b) 6 (c) 3.61 x 1024 (d) 7.227 x 1024 (e) 7.528 x 1022 11. (2) How many grams of oxygen, O2, are consumed in the combustion of 3.0 mol of butene, C4H8? (a) 576. g (b) 288. g (c) 384. g (d) 192. g (e) 128. g 12. (2) How many moles of carbon dioxide are formed in the combustion of 3.0 mol of butene, C4H8? (a) 16.0 mol of CO2 (b) 12.0 mol of CO2 (c) 4.0 mol CO2 (d) 3.0 mol CO2 (e) 9.0 mol CO2 13. (2) The number of hydrogen atoms in 156 g of C3H8O3 is (a) 8.17 x1024 (b) 4.82 x 1024 (c) 3.67 x 1025 (d) 1.56 x 1024 (e) 4.76 x 1023 14. (2) Calculate the number of moles in 156 g of C3H8O3 (a) 156 mol (b) 6.02 x 1023 mol (c) 2.17 mol (d) 1.70 mol (e) 4.75 mol 15. (2) What is the weight in grams of one mole of magnesium nitrate, Mg(NO3)2? (a) 164.09 g (b) 86.31 g (c) 110.61 g (d) 148.31 g (e) 136.02 g 16. (2) In the structural formula of a molecular compound each element symbol represents (a) an element (b) one mole (c) one atom (d) one molecule (e) one gram atomic weight 17. (2) The simplest formula of the compound formed from Sc3+ and Si4-ions will be (a) Sc3Si4 (b) Sc3Si (c) ScSi4 (d) ScSi3 (e) Sc4Si3 18. (2) A molecular formula (a) is a procedure for making a molecule (b) gives the number of molecules in a mole of a molecular compound (c) is a diagram showing how atoms are bonded in a molecule (d) is the same as an empirical or simplest formula (e) gives the number of atoms of each element in a molecular compound 19. (2) The balanced equation for the combustion of two moles of C10H14 requires (a) 7 H2O (b) 20 CO2 (c) 14 O2 (d) 16 O2 (e) 28 H2O 20. (2) The balanced equation for the combustion of one mole of C8H12 requires (a) 16 CO2 (b) 10 O2 (c) 12 H2O (d) 10 H2O (e) 11 O2 21. (2) Which of the following compounds is molecular (covalent) (a) Ni3Cu (b) AlF3 (c) PF3 (d) MgCa3 (e) K3N 22. (2) Which of the following compounds is ionic? (a) ZnCu0.553 (b) SCl2 (c) OCl2 (d) MgCl2 (e) CCl2 23. (2) Find the mass in grams os 3.00 x 1024 methane (CH4) molecules. (a) 79.7 g (b) 8.0 g (c) 9.6 x 1024 g (d) 48.0 g (e) 69.7 g 24. (2) Ammonia (NH3) will react with fluorine to produce N2F4 and HF according to the balanced equation 2 NH3 + 5 F2 N2F4 + 6 HF How many moles of ammonia are needed to react completely with 3.6 mol of F2? (a) 9.0 mol (b) 2.8 mol (c) 0.72 mol (d) 1.4 mol (e) 7.2 mol 25. (2) The correct name for P3- is (a) potassium(III) ion (b) phosphoric ion (c) phosphide ion (d) potassium-3(e) none of these ...
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