chemistry hw

homework #3 CHE 221 General Chemistry I Concordia University—Irvine Due: 2016 August 31 – September 1 1. A 0.321-g sample of aluminum is reacted with 1.000 g of solid sulfur to produce a specific

aluminum-sulfide compound. After the reaction, all of the aluminum is used and the mass of un-reacted sulfur is 0.430 g. What is the mass of the compound produced?

2. A 0.847 g sample of nickel reacts with chlorine producing 1.870 g nickel(II) chloride as the

only product. Using the law of constant composition, determine the mass of nickel contained in a 5.054 g sample of nickel(II) chloride.

3. The element “X” forms two compounds with element “Y”. In the first compound, 1.000 g X is

combined with 0.406 g Y. In the second compound, 2.000 g X reacts with 1.218 g Y. Show that these results are consistent with Dalton’s law of multiple proportions.

4. For the following isotopes, write their symbols in the form

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Z AE

a. arsenic-75 b. gold-197 5. Indicate the number of protons, neutrons, and electrons in each of the following atoms: a. tin-119 b. calcium-40 6. Indicate the number of protons, neutrons, and electrons in each of the following atoms: a. 131Xe b. 93Nb 7. Indicate the number of protons, neutrons, and electrons in each of the following ions: a. 56Fe3+ b. 133Cs1+ 8. Indicate the number of protons, neutrons, and electrons in each of the following ions: a. 80Br – b. 32S2– 9. The masses and percent abundances of the four un-naturally occurring isotopes of the

imaginary element notrealium are 71Nt, 70.2737 u, 17.054%; 73Nt, 72.2532 u, 24.531%; 77Nt, 76.2123 u, 13.067%; and 74Nt, 73.2430 u, 45.348%. Calculate the weighted-average atomic mass of notrealium in atomic mass units, u.