Optional Review Set      Answers
This set of questions is optional. If you completed the mandatory review set without problems you may skip it.
If you had problems then you'd better do it.

1.      Where is nearly all of the mass of an atom located? Explain your answer in terms of what contributes to this mass. 
2. Calcium arsenate, Ca3(AsO4)2, is a poison sometimes used to kill insects on plants. What is the mass of 0.586 mole of calcium arsenate? 
3. Calculate the formula weight of Fe4[Fe(CN)6]3.

4. Which of the following atomic species have a) 1,     b) 2,   or  c) 3 unpaired electrons in their outer shell?           H, He, Li, Be, C , N, O, F, Ne. 
5. Define monoprotic acid, diprotic acid and polyprotic acid. 
6. An oxide of a certain element produced an acidic solution when dissolved in water. The oxide has the empirical formula X2O3, where X represents the symbol for the element. Is the element X a metal or a nonmetal? In which group in the periodic table does it belong? 
7. Which alkaline earth metal is used in flashbulbs and flares? Why? Explain using a chemical equation. 
8. Give Lewis structures for (a) CS2, (b) CN-, (c) SeO3, and (d) SeO2
9. Which of these bonds is most polar and which is least:   SO, ClCl, or   ClO?     Justify your arrangement. 
10. Write the formulas for 

(a) aluminum sulphide         (b) strontium fluoride 

(c) titanium(IV) oxide         (d) chromous bromide 
11. Write molecular, ionic and net ionic equation for the reaction between Pb(NO3)2 and Fe2(SO4)3.
12. One way to prepare iodine is to mix sodium iodate, NaIO3, with hydriodic acid, HI. The following reaction occurs. 

NaIO3 + 6 HI --------> 3 I2 + NaI + 3 H2O

Calculate the number of moles and the number of grams of iodine that can be made this way from 16.4 g of NaIO3