Chemistry 200
Exam 1 Review Problems
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1.08 x 1023 atoms
1. Calculate the number of atoms in 10.0 grams of Fe.
2. Calculate the percent (by mass) of oxygen in H2O to three significant figures.
88.8 %
3. Calculate the number of moles of carbon in 50.0 g of benzene C6H6
3.84 mol C
4. A substance is found to be 38.7 % C, 9.7 % H and 51.6 % O by mass.
mass is 62.1 g/mole. What is its molecular formula?
C2H6O2
5.
a)
b)
c)
d)
e)
6.
Name the following:
Ca(OH)2 calcium hydroxide
KCN
potassium cyanide
HClO4(aq) perchloric acid
FeSO4
iron (II) sulfate
Na2O
sodium oxide
Its molar
f) SF6
sulfur hexafluoride
g) MgSO4  2H2O magnesium sulfate
dihydrate
h) Na2O2
sodium peroxide
What are the formulas of the following compounds?
a) sodium sulfite
Na2SO3
b) potassium permanganate
KMnO4
c) calcium sulfide
CaS
d) aluminum hydroxide
Al(OH)3
e) mercury (II) phosphate
Hg3(PO4)2
f) tetraphosphorus trisulfide P4S3
g) nitrous acid
HNO2
7. Which of the following is not an example of a chemical change?
a)
b)
c)
d)
e)
converting gasoline to carbon dioxide and water
digesting starch to give glucose
grinding sucrose crystals into powdered sugar
smoking tobacco
generating carbon dioxide from baking soda and vinegar
8. The density of ethyl alcohol is 0.789
of ethyl alcohol ? 45.0 mL
9.
How
g/mL.
What is the volume of 35.5 grams
many significant figures are in the mass measurement 0.050 gram?
2
10.
If an automobile engine has a volume of 155 in3, what is the volume in cm3 ?
( 2.54 cm = 1 in exactly) 2.54 x 103 cm3
11.
Convert
25 μL
into
milliliters
0.025 mL
12.
If 5.58 g of powdered iron react with powdered sulfur to produce 8.79 g of
iron sulfide, what is the mass of reacting sulfur? 3.21 g
13.
Sodium chloride, table salt, melts at 801C.
the Fahrenheit scale ? 1474F
14.
Express this number in scientific notation:
What is the melting point on
0.00104 centimeter 1.04 x 10-3 cm
15.
What is the mass in kilograms of a beaker that weighs 101 grams?
16.
Convert 12 gcm2/s2 to Joules (kgm2/s2) 1.2 x 10
–6
0.101 kg
J
17. A 1.013 g sample of a hydrate, ZnSO4  X H2O is dissolved in pure water and the
sulfate ion is precipitated by adding an excess of barium chloride solution. The
mass of pure dry barium sulfate obtained is 0.8223 g. What is the formula of the
zinc hydrate? ZnSO4  7H2O hint: “7” is the ratio of moles of water to moles of
zinc sulfate in the hydrate. mol Zn sulfate = mole of sulfate = mole Ba sulfate.
To get mole of water you need to first get g water: subtract g Zn sulfate (you
have moles) from g sample. Now you can calc the mole ratio.
18.
0.01981 g of an acid containing only C, H, and O undergoes combustion
(reaction with O2) to yield 0.04198 g carbon dioxide and 0.00645 g water. What is
the empirical formula of the acid? C4H3O2
19. The maximum allowable concentration of carbon monoxide in urban air is 10
mg/m3 over an eight-hour period. At this level, what mass of CO in grams is
present in a room measuring 8.0 x 12.0 x 20.0 ft ? 0.54 g
20. An English unit used in pharmaceutical work is the grain (gr). There are 15
grains in 1 gram. An aspirin tablet contains 5.0 gr of aspirin. A 145 lb person
takes two aspirin tablets. Calculate the dosage of aspirin, which is the number
of milligrams of aspirin per kilogram of body weight. (1 lb = 453.5 g) 10.1 mg/kg
21. The dosage of an arthritis medicine for dogs is given as
1.5 – 1.7 mg / kg body weight. If my dog weighs 70. lbs and the drug comes as 100
mg tablets, how many tablets should my dog get? (1 lb = 453.5 g) half of a
tablet (50 mg)
True or False
22.
A compound is a pure substance that cannot be broken down any further by
ordinary chemical reaction. false
23.
Li2O is dilithium oxide. false
24.
The nucleus of one atom of
25.
The name of the family of potassium is “alkali metal". true
18O
contains 18 neutrons and 8 protons.
26.
Sodium chloride is a mixture.
27.
All atoms of an element have the same mass.
false
false
false
More Calculations:
28. Given the reaction:
2C2H6 + 7O2 ─────> 4CO2 + 6H2O
How many moles of O2 will react completely with 12.00 moles of C2H6 ?
29. Given the equation:
4FeS2 + 11O2 ─────> 2Fe2O3 + 8SO2
If you react 85 grams of FeS2 with excess O2 , how many grams of
get? 57. g
30.
42.00 mol
Given the reaction:
2C2H6
+

7O2
Fe2O3 should you
4CO2
+
6H2O
If 28.0 grams of C2H6 are reacted with excess oxygen, and 70.0 grams of CO2
produced , what is the percent yield of the reaction?
? 85.4 %
31.
Given the reaction:
If 15.00 g of H2
16.9 g
2
H2
+
are mixed with 15.0 g of O2
O2

are
2 H 2O
what mass of water is produced?
32. What is the molarity of a HCl(aq) solution made by dissolving 0.20 moles of
HCl(g) in enough water to make 40.0 mL of solution?
33.
5.0 M
What mass of NaOH(s) is required to prepare 250 mL of 50.0 mM NaOH(aq)?
0.50 g
34.
How many mL of 12 M HCl(aq) do you need to prepare 150.0 mL of 1.5 M HCl(aq)?
19 mL
35. If 75.0 g of Na2SO4 are dissolved in water to make 1.50 L of solution, what
are the concentrations (molarity) of all the ions in the final solution? 0.704 M
Na+, 0.352 M SO4236.
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37.
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38. Element X has three naturally occurring isotopes. The masses (amu) and % abundances of the isotopes
are given in the table below. The average atomic mass of the element is _41.54____ amu.
39. – 41. See notes in packet for chp 2.
42. Provide the products of the following reaction and balance:
2C6H10
+
17O2
CO2 + 10H2O
What type of reaction is this? combustion
43. Give the mass number, #protons, #neutrons and #electrons for the isotope strontium-88
Mass # 88; 38 protons; 50 neutrons; 38 electrons.