Download Test Review # 8 - Evan`s Chemistry Corner

Chemistry R: Form TR8-9A
Name ______________________________
TEST 8 REVIEW
Date _________________ Period _____
Test Review # 8
Chemical Formulas. A chemical formula consists of chemical
symbols, subscripts, and, in some cases, a coefficient. The chemical
symbols show which elements are present in the compound. Subscripts
are small numbers written to the lower right of the symbol to which
they refer.
Example (Atoms in a Formula)
5(NH4)3PO4 . . . . . . . . . . . . N = 15, H = 60, P = 5, O = 20, TOTAL = 100
Symbols
Coefficient
Cu(NO3)2•3H2O
Subscripts
Formula Writing. The quickest way to determine the formula of a
compound of two elements or polyatomic ions is to use the CrossOver Rule. Look up the oxidation state of each element or ion and
reduce to lowest terms. Then cross over the oxidation states in lowest terms without the sign to find the subscripts as shown
in the diagram to the right and the example below.
Al+3
and
CO32–
Al2(CO3)3
Finding the Charge on Polyvalent Metals. Many transition metals have more than one oxidation state. They are called polyvalent. The
fact that a metal is polyvalent
Finding the Charge on the Cation
becomes important when the
Prepare a table as shown to the right.
compound is named. In order to
Step 1:
List the subscripts for the cations and
properly name a compound, it is
the anions.
necessary to first check the
Step 2:
Look up the oxidation state of the
anion on the Periodic Table.
Periodic Table to see if the
Step 3:
Multiply the oxidation state of the
metal is polyvalent. If it is, you
anion by the its subscript to get the
need to figure out the oxidation
total charge.
state of the metal by checking to
Step 4:
Determine the total charge of the
cations by calculating the number
see which one will make the
which, when added to the total charge
sum of the oxidation states in
of the anions, gives the compound a
the compound add up to zero.
total charge of zero.
The process is shown in the box
Step 5:
Divide the total charge of the cations
by the subscript of the cation to get
to the left. The process is only
the oxidation state.
applied for metals that have
more than one oxidation state.
Test Review # 8
Chemistry R: Form TR8-9A
TEST 8 REVIEW
Page 2
Answer the questions below by circling the number of the correct response
1. What is the total number of oxygen atoms in the formula
MgSO4•7H2O? [The • represents seven units of H2O attached to one
unit of MgSO4.] (1) 11 (2) 5 (3) 7 (4) 4
2. In the formula for water, H2O, the number 2 refers to the number of
(1) hydrogens and oxygens, (2) waters, (3) hydrogens only,
(4) oxygens only.
3. How many atoms are in 4Al(ClO3)3•6H2O (1) 124 (2) 70 (3) 31
(4) 10
4. The number of atoms in Cu3(PO4)2 is (1) 13, (2) 9, (3) 10, (4) 24.
5. Which of the following has the most oxygen?
(2) 3Ba3(PO4)2 (3) 2(NH4)2CO3 (4) 3Al(CO3)3
(1) 4Fe2O3
Answer questions 6-13 by referring to the formula below:
3FeSO4•7H2O
18. The oxidation state of chromium is +6 in (1) Cr2(CO3)3 (2) CrCl2
(3) Cr(PO4)2 (4) CrS2O3
19. In which of the following compounds is the oxidation state of copper
+1? (1) CuF (2) CuCl2 (3) CuC2O4 (4) Cu3(PO4)2
20. What is the oxidation state of manganese in Mn(CO3)2? (1) +7
(2) +2 (3) +3 (4) +4
21. What is the oxidation state of nickel in NiCr2O7? (1) +1 (2) +2 (3) +3
(4) +4
22. What is the formula for a compound of barium and fluorine? (1) BaF
(2) BaF2 (3) Ba2F (4) Ba2F2
23. What is the formula for a compound of magnesium and oxygen?
(1) MgO (2) Mg2O (3) MgO2 (4) Mg2O2
6. How many substances are shown in the formula above? (1) 1 (2) 2
(3) 3 (4) 4
24. What is the formula for a compound of potassium and thiosulfate
[S2O32–]? (1) KS2O3 (2) K2S2O3 (3) K(S2O3)2 (4) K2(S2O3)2
7. How many oxygen are shown in the formula above? (1) 12 (2) 19
(3) 7 (4) 33
25. What is the formula for a compound of NH4 and CO3? (1) NH4CO3
(2) (NH4)2CO3 (3) NH4(CO3)2 (4) NH3CO4
8. How many iron are shown in the formula above? (1) 12 (2) 21 (3) 3
(4) 33
26. What is the formula for a compound of calcium and sulfur? (1) Ca2S
(2) CaS2 (3) CaS (4) Ca2S2
Answers
22.
23.
24.
25.
26.
2
1
2
2
3
17. What is the oxidation state of copper in Cu3PO4? (1) 1 (2) 2 (3) 3
(4) 4
1
3
1
4
2
16. What is the oxidation state of tin in SnO2? (1) 1 (2) 2 (3) 3 (4) 4
17.
18.
19.
20.
21.
15. In which compound is the oxidation state of iron +3? (1) FeCl2
(2) FeO (3) FePO4 (4) FeS2O3
1
3
2
3
4
14. How many oxygens are in 2CuSO4•5H2O (1) 9 (2) 18 (3) 20 (4) 40
12.
13.
14.
15.
16.
13. The function of the dot in the formula above is to (1) multiply
coefficients, (2) multiply subscripts, (3) separate different
substances, (4) show a chemical reaction.
4
3
2
4
2
12. The numbers 2 and 4 shown in the formula above are (1) subscripts,
(2) coefficients, (3) oxidation states, (4) electronegativities
7.
8.
9.
10.
11.
11. The numbers 3 and 7 shown in the formula above are (1) subscripts,
(2) coefficients, (3) oxidation states, (4) electronegativities
1
3
1
1
4
2
10. How many atoms are shown in the formula above? (1) 189 (2) 39
(3) 90 (4) 81
1.
2.
3.
4.
5.
6.
9. How many hydrogen are shown in the formula above? (1) 14 (2) 42
(3) 21 (4) 33