AP Chemistry
Worksheet : Ch. 3-1
Name :
Date :
Questions 1-6 (Letters can be used more than once).
_____ 1. Forms monatomic ions with a +1 charge.
_____ 2. Metallic element forming a compound with the formula KXO4.
a. Cl
b. S
c. Na
d. Mn
e. Zn
_____ 3. Forms a compound with the formula K2XO4.
_____ 4. Forms oxides that when combined with water will form a basic solution.
_____ 5. Transition metal forming colorless solutions with ions having a 2+ charge.
_____ 6. A transition metal forming colored solutions with ions having more than one oxidation state.
_____ 7. (T/F) Molecular formulas are always in the lowest whole number ratio.
_____ 8. (T/F) Empirical and molecular formulas may be the same for a compound.
_____ 9. What is the empirical formula of benzene, an aromatic hydrocarbon with the formula C6H6?
a. C6H6
b. CH
c. C2H2
d.C3H3
_____10. (T/F) The atomic mass of carbon (C) is given in the periodic table as 12.01, therefore every carbon
atom has a mass of 12.01 amu.
_____ 11. (T/F) The atomic mass of carbon (C) is given in the periodic table as 12.01, therefore most carbon
atoms have a mass of 12.01 amu.
_____ 12. (T/F) In a 5.0 gram sample of pure carbon, not one atom of carbon will have a mass of 12.01 amu.
13. The element magnesium (Mg) has three stable isotopes with the following masses and abundances:
Calculate the average atomic mass (the atomic weight) of
Isotope Mass (amu) Abundance magnesium from these data.
24
78.99%
Mg 23.9850
25
24.9858
10.00%
Mg
26
Mg
25.9826
11.01%
14. Assume that element Uus is synthesized and that it has the following stable isotopes:
284
Uus (283.4 amu) 34.60%
285
Uus (284.7 amu) 21.20%
288
Uus (287.8 amu) 44.20%
What is the value of the average atomic mass for Uus that would be listed on the periodic table?
15. An element is a mixture of two isotopes. One isotope of the element has an atomic mass of 34.96885 amu
and has a relative abundance of 75.53%. The other isotope has an atomic mass of 36.96590 amu. Calculate
the average atomic mass and identify the element.
16. The element europium exists in nature as two isotopes: 151Eu has a mass of 150.9196 amu, and 153Eu has a
mass of 152.9209 amu. The average atomic mass of europium is 151.96 amu.Calculate the relative
abundance of the two europium isotopes.
AP Chemistry – ws-3-1
17. The mass spectrum of bromine (Br2) consists of three peaks /with the following characteristics:
Mass(amu)
157.84
159.84
161.84
Relative size
0.2534
0.5000
0.2466
How do you interpret these data?
18. a. Calculate the mass of 500. atoms of iron (Fe) in grams.
b. How many Fe atoms and how many moles of Fe atoms are in 500.0 g of iron?
19. Diamond is a natural form of pure carbon. How many atoms of carbon are in a 1.00-carat diamond (1.00
carat = 0.200 g)?
20. A diamond contains 5.0 x 1021 atoms of carbon. How many moles of carbon and how many grams of
carbon are in this diamond?
21. Aluminum metal is produced by passing an electric current through a solution of aluminum oxide (A12O3)
dissolved in molten cryolite (Na3AlF6). Calculate the molar masses of A12O3 and Na3AlF6.
22. Calculate the molar mass of the following substances.
a. NH3
b. N2H4
c. (NH4)2Cr2O7
23. How many moles of compound are present in 1.00 g of each of the compounds in Exercise 22.
24. How many grams of nitrogen are present in 5.00 mol of each of the compounds in Exercise 22.
25. How many atoms of nitrogen are present in 1.00 g of each the compounds in Exercise 22.
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26. Ascorbic acid, or vitamin C (C6H8O6), is an essential vitamin. It cannot be stored by the body and must be
present in the diet. What is the molar mass of ascorbic acid? Vitamin C tablets are taken as a dietary
supplement. If a typical tablet contains 500.0 mg of vitamin C, how many moles and how many molecules
of vitamin C does it contain?
27. The molecular formula of acetylsalicylic acid (aspirin), one of the most commonly used pain relievers, is
C9H8O4.
a. Calculate the molar mass of aspirin.
b. A typical aspirin tablet contains 500. mg of C9H8O4. How many moles of C9H8O4 molecules and how
many molecules of acetylsalicyclic acid are in a 500. mg tablet?
28. Determine the mass in grams of the following:
a. 3 x 1020 N2 molecules
b. 1.5 x 102 mol N2
c. 2.00 x 10-15mol N2
d. 18.0 picomoles of N2
e. 5.0 nanomoles of N2
29. How many atoms of carbon are present in 1.0 g of each of the following?
a. CH3CO2H
b. Na2CO3
c. C6H12O6
Calculators may not be used on the following problems :
_____ 30. For which of the following compounds does 0.48 mol have a mass of 86 grams?
a. AlCl3
b. NF3
c. C6H12O6
d. O3
e. C2H4N2O
_____ 31. How many moles are there in 0.24 grams of ozone(O3)?
a. 2.0 mol
b. 0.20 mol
c. 0.50 mol
d. 0.050 mol
e. 0.0050 mol
_____ 32. How many moles of O2 are needed to form 3.2 g of SO2 (molar mass = 64.07 g)?
a. 2.0 mol
AP Chemistry – ws-3-1
b. 0.50 mol
c. 0.25 mol
d. 0.050 mol
e. 0.020 mol
_____ 33. The weight of H2SO4 (molecular weight is 98.1 amu) in 25.0 ml of a 2.0 molar solution is
a. 4.9 g
b. 9.8 g
c. 49g
d. 98g
e. 0.49g
_____ 34. How many grams of calcium sulfate (MW = 136.15 g) contain 32.0 grams of oxygen?
a. 136 g
b. 68.1 g
c. 34.5 g
d. 17.3 g
e. 8.65 g
_____ 35. How many moles are there in 50. g of calcium carbonate?
a. 2.0
b. 0.50
c. 0.75
d. 1.0
e. none of the above
_____ 36. How many grams of silver are there in 0.0500 moles of silver sulfide?
a. 54.0g
b. 10.8g
c. 21.6g
d. 12.5g
e. 24.9g
_____ 37. How many moles of hydrochloric acid are needed to completely react with 131 g of zinc?
a. .050 mol
b. 1.0 mol
c. 2.0 mol
d. 3.0 mol
e. 4.0 mol
_____ 38. Which of the following compounds has a S:O ratio of 1:1.5 by mass?
a. SO2
b. SO3
c. SO4
d. S2O3
e. S2O5
Answers to selected problems 13. 24.31 amu
14. 285.6 amu 15. 35.46 amu, chlorine
16. 48%
151
Eu and 52% 153Eu
17. There are two isotopes of Br : 79Br and 81Br The lightest Br2 molecules are
composed of to atoms of the lighter isotope… etc. 18a. 4.637 x 10-20 g Fe 18b. 8.953 mol Fe, 5.391 x 1024
atoms Fe
19. 1.00 x 1022 atoms C 20. 8.3 x 10-3 mol C, 0.10 g C 21. 101.96 g/mol, 209.95 g/mol 22c.
252.08 g/mol
23a. 0.0587 mol NH3 23c. 3.97 x 10-3 mol (NH4)2Cr2O7 24a. 70.1 gN 24c. 140. g N
22
25a. 3.54 x 10 atoms N 25c. 4.78 x 1021 atoms N 26. 176.12 g/mol, 2.839 x 10-3 mol, 1.710 x 1021
molecules 27a. 180.17 g/mol 27b. 1.67 x 1021 molecules 28a. 1.40 x 10-2 g N2 28c 5.60 x 10-14 g N2
28e. 1.4 x 10-7 g N2 29a. 2.0 x 1022 atoms C 29c. 2.0 x 1022 atoms C
AP Chemistry – ws-3-1