Download 1411 Practice Exam 1

Chemistry 1411 Practice Exam 1, Chapters 1-4 Chang
Show your calculations clearly on show work problems. A periodic table is also attached to the
end of the exam. Good luck!
1.
Give the number of significant figures in the following numbers (2 pts each):
a) 5.204 X 102 mL
2.
3.
______
b) 0.0010270 mole
______
Carry out the following operations and give your answers with the correct number of
significant figures (2 pts each):
a) 14 + 6.724 + 0.0099
=
_______________
b) 52.35 X 5.7 ÷ 29.8
=
_______________
Make the following conversions (2 pts each, show all steps):
a) 5 ft, 9 in to m (1 in = 2.54 cm)
b) 77°F to Kelvin
c) 7.92 lb/gal to g/mL (1 lb = 453.6 g, 1 gal = 3.785 L)
4.
When an object claimed to be made of pure gold was immersed in a graduated cylinder
containing water, the water level rose from 25.0 mL to 25.8 mL. The mass of the object was
7.1 g. What is the density of the object in grams per mL? (3 pts)
5.
(3 pts) Isotopes are atoms that:
a) have different atomic numbers
b) have the same mass number
c) have the same number of protons but different numbers of neutrons
d) have different numbers of electrons
6.
Which of the following is an extensive property? (3pts)
a) volume
b) boiling point
c) density
d) freezing point
7.
What is the number of protons, neutrons, and electrons in the nitrogen-14 –3 ion? (3 pts)
a) 7 protons; 7 neutrons; 7 electrons
b) 7 protons; 7 neutrons; 10 electrons
c) 8 protons; 6 neutrons; 14 electrons
d) 7 protons, 7 neutrons; 4 electrons
8.
Which of the following elements is a nonmetal? (3 pts)
a) calcium
b) sulfur
c) zinc
d) mercury
Which of the following is a transition element? (3 pts)
a) Br
b) Pb
c) Ba
d) Os
Which of the following elements is a halogen? (3 pts)
a) Fe
b) K
c) Br
d) Te
9.
10.
11.
Which of the following compounds is a molecular compound? (3 pts)
a) barium chloride b) carbon dioxide c) ferric nitrate
d) magnesium oxide
12.
(3 pts) A set of measurements has good precision if
a) the average is close to the true value
b) the measurements are in close agreement with each other but are not necessarily correct
c) a large number of measurements are made
d) a small number of measurements are made
13.
14.
Name the following compounds (1 pt each):
a) CuCl2
_________________________ b) Li2CO3
______________________________________
c) NO2 (g)
_________________________ d) Na2SO3
______________________________________
Write the chemical formulas for the following compounds (1 pt each):
a) aluminum oxide ___________________ b) magnesium phosphate __________________________
c) iron(III) bromide ___________________ d) sulfuric acid ___________________________________
15.
Balance the following reactions (2 pts each):
a)
_____ N2 (g) +
_____ H2 (g)
_____ NH3 (g)
b)
_____ Al (s) +
_____ HBr (aq)

_____ AlBr3 (aq) +
c)
_____ C8H18 (l) +
_____ O2 (g)

_____ CO2 (g) +

_____ H2 (g)
_____ H2O (l)
16.
What is the mass percentage of sulfur in Na2SO4? (3 pts)
17.
How many moles of Na2SO4 are in 25.0 g of this compound? (3 pts)
18.
A compound is 70.57% C, 5.94% H, and 23.49% O. What is the empirical formula of the
compound? (3 pts)
19.
Naturally-occurring copper is composed of 69.17% copper-63 with an atomic weight of
62.9396 amu, and 30.83% of another copper isotope. If the average (weighted average)
atomic weight of copper is 63.546 amu, what is the atomic weight of the other copper
isotope? (3 pts)
20.
Copper metal reacts with dilute nitric acid according to the following equation:
3Cu (s) + 8HNO3 (aq)  3Cu(NO3)2 (aq) + 2NO (g) + 4H2O (l)
If we start with 0.500 mol of copper metal, how many moles of water will be formed? (3 pts)
21.
If 5.00 g of magnesium metal is burned in the presence of excess O2, how many grams
of MgO will form? (3 pts)
22.
125 mL of 12.0 M HCl solution is diluted with water to a final volume of 1.00 L. What is the
molarity of the diluted solution? (3 pts)
a) 3.75 M
b) 1.50 M
c) 0.185 M
d) 0.015 M
23.
What is the molarity of an NaCl solution prepared by dissolving 9.3 g of NaCl in 350 mL of
solution? (3 pts)
a) 18 M
b) 0.16 M
c) 0.45 M
d) 27 M
24.
How many grams of NaOH are in 500 mL of 0.175 M NaOH solution? (3 pts)
a) 2.19 X 10–3 g
b) 114 g
c) 14.0 g
d) 3.50 g
25.
When aqueous solutions of Ba(NO3)2 and K2SO4 are mixed, a precipitate of BaSO4 results.
Write the molecular, ionic, and net ionic equation for this double displacement reaction. (6 pts)
26.
What is the oxidation state of chlorine in the chlorate ion, ClO3 ? (3 pts)
a) –1
b) +3
c) +5
d) +7
–
27.
Based on the equations below, which metal is the most active? (3 pts)
Ni(s) + Pb(NO3)2 (aq)  Ni(NO3)2 (aq) + Pb(s)
Cu(s) + Pb(NO3)2 (aq)  No reaction
Cu(s) + 2Ag(NO3) (aq)  2Ag(s) + Cu(NO3)2 (aq)
a) Ni
b) Ag
c) Cu
d) Pb
28.
Calculate the molarity of hydrochloric acid, HCl, in a solution if 25.00 mL of that solution
required 35.74 mL of 0.1522 M KOH for complete neutralization in a titration. (3 pts)
a) 0.2668 M
b) 0.8003 M
c) 0.2176 M
d) 0.1345 M
29.
If a copper penny weighs 3.00 g, how many copper atoms are in the penny? (3 pts)
30.
Classify the following reactions (combination, decomposition, single displacement, or double
displacement). (1 pt each)
31.
HCl (aq) + NaOH (aq)  NaCl (aq) + H2O (l)
____________________________________
H2 (g) + CuO (s)  Cu (s) + H2O (l)
____________________________________
2 KClO3 (s)  2 KCl (s) + 3 O2 (g)
____________________________________
2 Mg (s) + O2 (g)  2 MgO (s)
____________________________________
A compound has the empirical formula CH2 and molecular weight 112.21 g/mol. What is the
molecular formula of the compound? (3 pts)
Answers
1. a) 4
b) 5
2. a) 21
b) 1.0 X 101
3. a) 1.8 m
b) 298 K
c) 0.949 g/mL
4. 9 g/mL
5. c
6. a
7. b
8. b
9. d
10. c
11. b
12. b
13. a) copper(II) chloride or cupric chloride
c) nitrogen dioxide
14. a) Al2O3
c) FeBr3
b) Mg3(PO4)2
d) H2SO4
15. a) 1, 3, 2
b) 2, 6, 2, 3
16. 22.574 %
17. 0.176 mol
18. C4H4O
19. 64.907 amu
20. 0.667 mol H2O
21. 8.29 g of MgO will form
22. b
23. c
b) lithium carbonate
d) sodium sulfite
c) 2, 25, 16, 18
24. d
25. Molecular or formula equation:
Ba(NO3)2 (aq) + K2SO4 (aq)
BaSO4 (s) + 2 KNO3 (aq)
Ionic equation:
Ba2+ (aq) + 2 NO3– (aq) + 2 K+ (aq) + SO42– (aq)
Net ionic equation:
Ba2+ (aq) + SO42– (aq)
26. c
27. a
28. c
29. 2.84 X 1022 Cu atoms
30. a)
b)
c)
d)
double displacement
single displacement
decomposition
combination
31. C8H16
BaSO4 (s)
BaSO4 (s) + 2 K+ (aq) + 2 NO3– (aq)