Instructions:  Circle the best answer for each question.

The Reagent Shelf.
These compounds are available as pure substances or in solution, as appropriate for your needs.
 

Acids	Bases	Boron	Carbon	Halogens	Hydrogen
H2SO4 H3PO4 HCl HNO3	Ca(OH)2 KOH NaOH	B(OH)3 B2O3 BF3 Na2B4O7.10 H2O NaBH4 NaBO3.4 H2O	C(s)  CaC2 CO  CO2 Na2CO3 Na2CO3 NaHCO3	Br2 Cl2 I2 KBr  KI  NaCl	CaH2 H2 LiAlH4 NaBH4

 

Metals, Metal Salts	Oxygen	Nitrogen	Phosphorus	Silicon	Sulfur
Cu Cu(NO3)2 Mg MgO MnO2 Zn Zn(NO3)2	H2O H2O2 Na2O O2 O3	KNO3 NaNO2 NH3(aq) NH3(g)	Ca3P2 H3PO3 H3PO4 P(red) P4 P4O10	Si SiCl4	H2S FeS Na2S Na2SO3 NaHSO3 S8 SO2 SO3

ALKALINE EARTH METALS

1. Recall the lab in which you softened water by passing it through resin.  You tested the water before and after with a phosphate solution.  What was the purpose of this test?

A. to test that the pH had been lowered
B. to test for the presence of sodium ions.
C. to test for the presence of calcium and magnesium ions
D. to test the solubility of the ions in the water
E. to precipitate any remaining ions from the treated water

2.  Recall the experiment in which we burned magnesium in dry ice. Which of the following was NOT one of the products observed?
 

A. carbon  B. magnesium oxide C. magnesium carbonate

3. You heated metallic calcium in a test tube with a similar mass of sulfur.  After a few seconds, a fireball ensued producing

A. calcium silicate  B. calcium sulfide    C. calcium sulfite  D. calcium sulfate E. calcium bisulfite

4 - 5. Calcium fluoride crystallizes in the fluorite structure, a cubic arrangement of fluoride ions with the calcium ions located at half of the body centers.  Sketch a body-centered cell at right and use it to answer the next two questions. (Sketch required for credit on the next 2 questions!)

4. Which of the following compounds could, in principle, have the fluorite-like structure?

 A.  K2Se         B.  MgO         C.  KBr         D. Fe3(PO4)2         E. AlCl3

5. Determine the ratio of body-centered positions to corner positions (1 : 1, 1 : 2, 1 : 3, etc).  From your knowledge of the stoichiometry of calcium fluoride, what fraction of the body-centered positions must be occupied?

 A.  all B.  half C.  a third

6.  Dolomite, marble, limestone, Iceland spar have which of the following in common?

A. They all contain magnesium salts originally from the oceans.
B. They all are hydrates.
C. They are all commercially important minerals of magnesium.
D. They all are carbonates.
E. None of the above.

7. The primary chemical difference between gypsum and plaster of Paris is:

A. gypsum is calcium sulfate and plaster of Paris is calcium bisulfate.
B. the oxidation state of the anion.
C. the solubility of the salts.
D. gypsum is covalent and plaster of Paris is ionic.
E. the number of waters of hydration.

8 & 9.  Reagent Shelf Question.  What two reagents did you use to produce a fine precipitate of calcium carbonate?

A.    B.

10. Which single step was the most exothermic in the heat of formation of any salt.

A. ionization of metal to cation                  B. atomization of metal to gas phase
C. formation of anion                                 D. vaporization of non-metal
E. lattice energy

1.  C
2.  C
3.  B
4.  A
5.  B
6.  D
7.  E
8 and 9. Ca(OH)2(aq) + Na2CO3(aq)
10.  E