Chapter 7 Homework - 20 points total
Naming and writing ionic
formulas:
Remember: -The first symbol is positive
and called the name it is on the chart
-The second symbol is negative and changes
its name to –ide
or -ite
(with the only exception being OH-1 which is called
Hydroxide)
Section #1:
(indicate on your homework
paper which section and page number you are doing!)
Do practice problems #1-2 on p. 209
Do practice problems #1-2 on p. 213
Copy the names of the following acids onto
your homework.: HF, HCl, H3PO4,
HNO3, H2SO4, CH3COOH. You will find them in table 7-5 on p. 214
Assigning Oxidation Numbers
to Compounds: (look at the rules on p. 216 for help!)
Do practice problem #1 on p. 218 (remember
to write the section and page number)
Do Section review problem #1 p. 219
---------------------------------------------End of Section
#1--------------------------------------
Section #2:
Percent Composition: (a good
sample problem is on p. 227 of your book)
Find the Percent composition of each element in the following compounds’ empirical formulas:
1. NaCl 4. C6H12O6
2. H2O 5. CH3OH
3. Mg3(PO4)2
Empirical Formulas: (a good sample problem is on p. 229-230 of
your book)
Use
the percent composition of these compounds to determine the empirical formula
(Hint: You can figure out many of these
by balancing the ionic charges. Do that
to check your work. Realize that the
ones on the test will be all covalent, not ionic)
6. 11.0% H
and 89.0% O
7. 39. % Na and 60.7% Cl
8. 27.7%
Mg and 72.3% PO4 (Hint:Keep PO4 together, eg.
molar mass = 95.0 g/mol)
9. 32.4%
Na and 67.6% SO4 (Hint: Keep
SO4 together)
10. 40.0%
C, 6.67% H, and 53.3% O
11. 37.5% C, 12.5% H and 50.0% O
12. 66.0% Ca
and 34.0% P
13. 82.4% N and 17.6% H
Molecular
Formulas: Use the empirical formulas you found in questions #6-13 of the Empirical
Formulas section to answer these questions. NOTE: I made up these
compounds, they do not exist in real life - it is just an example of how to do
these type of problems.
(see p. 232-233
for a great sample problem)
6.
Molecular mass = 54.0 Empirical
Formula Mass = 18.0
7.
Molecular mass = 117 Empirical
Formula Mass = 58.5
8.
Molecular mass = 1320 Empirical
Formula Mass = 263
9.
Molecular mass = 568 Empirical Formula Mass = 142
Hydrates: Find the formulas for the following hydrates
(see sample problem 7-11 on p. 227-228 for help on these)
Answers
in mole ratio of compound to water
10. 0.391 g Li2SiF6, 0.0903 g H2O (1:2)
11. 0.737 g MgSO3, 0.763 g H2O (1:6)
12. 95.3 g LiNO3, 74.7 g H2O (1:3)
13. 76.9 g CaSO3, 23.1 g H2O (1:2)
14. 89.2 g BaBr2, 10.8 g H2O (1:2)
1. 39.3:60.7
2. 11:89
3. 27.7:23.6:48.7
4. 40:6.7:53
5. 37.5:12.5:49.9
6. H2O
7. NaCl
8. Mg3 (PO4) 2
9. Na2 SO4
10. CH2O
11. CH4O
12. Ca3P2
13. NH3
6. H6O3
7. Na2Cl2
8. Mg15(PO4)
10
9. Na8(SO4)
4