Chemical Formulas

Chemistry Test

Unit Six

Chemical Formulas

Choose the best answer to each of the following questions.

1. Which of the following represents the number of atoms of a given kind
    in a compound?
    a. oxidation number
    b. formula unit
    c. subscript
    d. coefficient

2. Which of the following is a salt?
a. H₂SO₄ b. C₂H₂ c. CO₂ d. MgO

3. How many atoms of oxygen are there in the compound Al₂(SO₄)₃?
    a. 12
    b. 7
    c. 4
    d. 1

4. A combination of symbols that represents the composition of a
    compound is a(n)
    a. isotope
    b. chemical formula
    c. polyatomic ion
    d. oxidation number

5. An atom that has a charge is called a (n)
    a. formula unit
    b. ion
    c. binary compound
    d. sotope

6. Compounds composed of nonmetals are called
    a. covalent
    b. ionic
    c. binary
    d. inert

7. An ion that has a 3+ oxidation number can combine with three other
    ions, if each of these ions has a charge of
    a. 3-
    b. 3+
    c. 1-
    d. 1+

8. Which of the following is a compound composed of lithium and the
    nitrate polyatomic ion?
    a. LiNO₃     b. NH₃     c. Li₂O
     d. Li₃N

9. The empirical formula for the compound C₁₂H₁₂N₆O₄ is
    a. C₆H₆NO₄    b. C₁₂H₆N₆O₄    c. C₁₂H₁₂N₆O₄    d. C₆H₆N₃O₂

10. How many total ions are represented by the formula 3K₂SO₃?
     a. 6
     b. 9
     c. 15
     d. 30

11. The apparent charge on the individual atom is represented by the
      a. oxidation number
      b. subscript
      c. formula unit
      d. coefficient

12. For the formula of an ionic compound to be correct, the algebraic
     addition of the charges on the atoms must add up to
     a. a number one less than the number of atoms in the compound
     b. zero
     c. a number equal to the number of atoms in the compound
     d. a number one greater than the number of atoms in the compound

13. The correct formula for nickel(II) chloride is
a. Ni₂Cl
b. Ni(ClO₃)₂ c. Ni₂ClO₃ d. NiCl₂

14. The symbol that is used to represent that a substance has been
      dissolved in water is
      a. (I)
      b. (Cr)
      c. (aq)
      d. (g)

15. Which of the following will be a better electrolyte?
a. Cr(NO₃)₃ b. NH₃ c. H₂O
d. C₆H₁₂O₆

Free Response

You must show all work and answer in complete sentences to receive full credit.

1. What is the relationship between valance electrons, the octet rule, and
the oxidation number of an ion?

2. In 1962, a scientist combined a noble gas with another element in a
chemical reaction for the very first time. The noble gas was xenon,
which was combined with fluorine to produce the compound XeF₄

(a) What is the name of this compound?
(b) What is the oxidation number of xenon in this compound?

3. Why can carbon have a +4 or –4 oxidation number?

4. Name the following covalent compounds:
a. CO
b. NO₂ c. P₃O₅

5. Name the following acids:
a. H₃PO₄ b. HclO₂

6. Write the chemical formulas and name all compounds.

	Br^-	CO₃^-2	N^-3
Al⁺³
Ba⁺²
Co⁺³