UNIT 7 REVIEW

Part 1 – Write the formulas for the following compounds:

1.)      chromium (III) acetate                        Cr(C2H3O2)3

2.)      silver iodide                                        AgI

3.)      calcium perchlorate                             Ca(ClO4)2

4.)      carbon disulfide                                  CS2

5.)      zinc hydroxide                                    Zn(OH)2

6.)      cesium phosphide                                 Cs3P

7.)      ammonium sulfate                                (NH4)2SO4

8.)      copper (I) oxide                                  Cu2O

Part 2 – Name the following compounds:

9.)      LiNO3                                                                                 lithium nitrate

10.)    PCl3                                                                                      phosphorus trichloride

11.)     ZnCO3                                                                                zinc carbonate

13.)    AlF3                                                                                     aluminum fluoride

14.)    NiS                                                    nickel (II) sulfide

15.)    NH4NO3                                                                           ammonium nitrate

16.)    K3N                                                    potassium nitride

Part 3 – Determine the oxidation number and percent composition of the underlined element in the compound:

17.)    K2C2O4                                                                               (2.+1) + (2.x) + (4.-2) = 0

2 + 2x -8 = 0

X = +3

24    x 100 = 14.4 % C
166.2

18.)    Ca(ClO)2                                                                           (1.+2) + (2.x) + (2.-2) = 0

2 + 2x -4 = 0

X = +1

71    x 100 = 49.6 % Cl
143.1

Part 4 – Solve the following problems:

19.)    Benzoic acid is a compound used as a food preservative.  The compound contains 68.8 % carbon, 4.95 % hydrogen, and 26.2 % oxygen.  What is the empirical formula for benzoic acid?  If the molar mass of the molecular formula is 122 g/mole, what is the molecular formula?     Empirical & Molecular Formula = C7H6O2

20.)    A hydrated sample of cobalt (II) chloride has a mass of 29.7 grams.  Once all of the water has evaporated from the sample, 16.2 grams of anhydrous salt remain.  What is the empirical formula for this hydrate?

CoCl2 .  6  H2O