Unit 0 – Chemistry Review
Section 3 – Chemical Formulas
Molecular (Covalent) Compounds
1. What information can we tell about a compound given its empirical formula?
2. What additional information is conveyed when we know its molecular formula?
3. What additional information to we know when we see its structural formula?
4. Two compounds have the same empirical formula; one is a gas at room temperature and the other is a liquid.
How is this possible?
5. Determine the molecular and empirical formula of the following:
a. The organic solvent benzene that has six carbon atoms and six hydrogen atoms
b. The compound silicon tetrachloride, a substance used to make computer chips
c. The reactive substance diborane, a compound with two boron atoms and six hydrogen atoms
d. The sugar glucose, a substance with six carbon, twelve hydrogen, and six oxygen atoms
6. Write down the molecular and structural formulas represented by the following models:
Ionic Compounds
7. Which of the following compounds below likely represents an ionic compound and which represents a covalent
compound? Explain your answer.
8. Predict the charge of the most stable ion each element below is capable of forming:
a. Mg
c. S
e. F
b. Al
d. K
f. O
g. N
h. Na
9. Fill in the table for the compound made from each cation and anion pair. Use parentheses when necessary.
Cl
Na+
NH4+
Sn2+
Hg22+
Al3+
Sn4+
NO3
S2
CO32
N3
PO43
OH
Naming Compounds: Molecular and Ionic
It is very important that you do as much of this as you can for memory. You will not be given the list on the AP test.
Show Formulas for the Following Compounds
calcium iodide
magnesium nitrate
iron (II) acetate
lead (IV) oxide
calcium hydride
copper (II) sulfide
ammonium ion
hydrogen sulfide
magnesium nitrate
lead (IV) oxide
potassium chromate
cadmium (II) bromide
copper (I) sulfide
aluminum acetate
antimony (V) sulfite
vanadium (V) carbonate
nickel (II) sulfate
arsenic (II) sulfite
tin (II) fluoride
lead (IV) sulfide
hydrogen bromide
lead (II) chlorate
manganese (II) oxalate
carbon tetrachloride
manganese (III) dichromate
ammonium sulfate
mercury (II) bisulfate
mercury (I) nitrite
cobalt (II) hydroxide
tin (IV) sulfide
lithium perchlorate
manganese (III) permanganate
tetraphosphorus decoxide
silver cyanide
Show Names for the Following Compounds
KCN
NaCl
SiH4
KSCN
SO3
AgIO
NO3-
HCN
ZnO2
CuCl2
SF6
KIO4
CO
CO2
(NH4)2C2O4
Fe(HSO3)3
LiBrO
NO3
Hg2Cl2
MgCr2O7
CuNO3
CBr4
Show Formulas and Names for the Following Acids
hydrobromic acid
HI
sulfurous acid
HC2H3O2
chlorous acid
HF
hydrochloric acid
H3PO3
phosphoric acid
HClO3
nitrous acid
H2CO3
hydrofluoric acid
H2SO3
perchloric acid
HClO2
Percent Composition and Empirical Formulas
10. A compound is 85.7% C and 14.3% H by mass. Determine its empirical formula.
11. In areas where temperatures get extremely cold, people must take special precautions to make sure machinery
runs properly. One compound contains 83% rubidium, 16% oxygen, and 1% hydrogen is used in low temperature
storage batteries. What is the empirical formula for this compound?
12. A form of phosphorus called red phosphorus is used in match heads. When 0.062 grams of red phosphorus burns
it combines with oxygen and 0.142 grams of product is formed. What is the empirical formula and name of this
substance?
13. A compound that is usually used as a fertilizer can also be used as a powerful explosive. The compound has the
composition, 35.00% nitrogen, 59.96% oxygen and the remainder being hydrogen. What is its empirical formula?
Given it is ionic, suggest a name for the compound.
14. The common pain medicine, Advil, contains the active ingredient Ibuprofen that has a molar mass of 184 g/mole.
Ibuprofen contains 75.73% C, 8.74% H, the remainder being oxygen. What are the empirical and molecular
formulae for Ibuprofen?
15. A compound is found to be 40% carbon, 6.7% hydrogen and 53.5% oxygen. Its molecular mass is 60 g/mol. What
is its molecular formula?
16. Epinephrine (adrenaline) is a hormone secreted into the bloodstream in times of danger and stress. It is 59.0%
carbon, 7.1% hydrogen, 26.2% oxygen, and 7.7% nitrogen by mass. Its molar mass is about 180 g/mol.
Hydrates
17. When 5.00 g of FeCl3 · xH2O are heated, 2.00 g of H2O are driven off. Find the chemical formula and the name of
the hydrate.
18. A 16.4 g sample of hydrated calcium sulfate is heated until all the water is driven off. The calcium sulfate that
remains has a mass of 13.0 g. Find the formula and the chemical name of the hydrate.
19. A hydrate is determined to be 45.43% water and 54.57% CoCl2. What is the formula and name of this hydrate?
20. What is the formula and name for a hydrate that is 90.7 g SrC2O4 (strontium oxylate) and 9.30 g H2O?