CH1410 Practice Exam #2 (Katz) Sp2015
Section 1 - Multiple Choice - Write the letter of the BEST CHOICE in the space provided. B
_____ 1. The energy sublevel for the highest energy electrons added to the elements U, Sr, Cl, and Cu
are, in the correct order,
A) s, p, d, f
B) f,s,p,d.
C) p, d,f, s.
D) f,p,d,s.
A
_____ 2. Which subshell letter corresponds to a spherical orbital?
A) s
B) p
C) d
D) f
C
_____ 3. What is the electron configuration for Kr?
A) 1s22s22p63s23p43d104s24p6
C) 1s22s22p63s23p64s23d104p6
B) 1s22s22p63s23p64s23d24p6
D) 1s22s22p63s23p24s23d104p6
B
_____ 4. Consider the electron configuration of the ion to determine which ion shown below has an
incorrect ionic charge?
A) Al3+
B) Se2+
C) Rb+
D) Ba2+
D
_____ 5. Which one of the following species has the electron configuration of 1s22s22p6?
1. Na+
2. O2-
3. F-
A) 1 and 2 only
C) 2 and 3 only
B) 1 and 3 only
D) 1, 2, and 3
D
_____ 6. Which of the following atoms is the largest?
A) Na
B) K
C) Rb
D) Cs
A
_____ 7. Which of the following atoms has the greatest metallic character?
A) Cs
C
B) Be
C) Cu
D) Ti
_____ 8. How many carbon atoms are in the formula unit Al2(CO3)3?
A) 9
B) 6
C) 3
D) 1
C
_____ 9. How many of each type of atom are there in the formula (NH4)2HPO4?
A) N = 2, H = 9, P = 1, O = 4
B) N = 1, H = 5, P = 1, O = 4
C) N = 2, H = 5, P = 1, O = 4
D) N = 2, H = 8, P = 1, O = 4
D
_____10. Which among the following elements does NOT exist as a diatomic molecule in nature?
A) hydrogen
B) nitrogen
C) fluorine
D) neon
D
_____11. Which of the following is a molecular compound?
A) barium sulfide
B) calcium acetate
C) potassium hydroxide
D) nitrogen monoxide
A
_____12. What is the name of CoS?
A) cobalt(II) sulfide
C) cobalt monosulfide
B) cobalt sulfide
D) cobaltous sulfur
B
_____13. What is the name of Ca(NO3)2?
A) calcium dinitrite
C) calcium nitride
B) calcium nitrate
D) calcium nitrite
D
_____14. What is the correct formula for potassium dichromate?
A) K(CrO4)2
B) KCr2O7
C) K2CrO4
D) K2Cr2O7
A
_____15. The charge of a vanadium ion in the compound V2O5 is:
A) 5+
B) 2+
C) 10+
D) 10-
C
_____16. What is the name of the molecular compound SO3?
A) sulfur oxide
B) sulfur(IV) oxide
C) sulfur trioxide
D) sulfur tetraoxide
C
_____17. What is the proper name for HBr (aq)?
A) hydrobromous acid
C) hydrobromic acid
D
B) hydrousbromic acid
D) bromous acidD) an isotope.
_____18. What is the formula mass for potassium nitrate?
A) 92.99 amu
B) 117.11 amu
C) 85.11 amu
D) 101.10 amu
C
_____19. A compound has a formula mass of 61.98 amu and is comprised of atoms of sodium and
oxygen in a definite ratio. The name of the compound described here is
A) sodium monoxide.
B) disodium oxide.
C) sodium oxide.
D) sodium dioxide.
D
_____20. A chromium oxide compound contains 104.0 grams of chromium and 48.0 grams of oxygen.
What is the most likely empirical formula of this compound?
A) CrO
B) CrO2
C) CrO3
D) Cr2O3
B
_____21. What is the molecular formula of a compound given the molar mass of the compound is
30.04 gram and the empirical formula is NH?
A) NH
B) N2H2
C) N2H6
D) N4H4
B
_____22. If you have 1.81 x 1024 atoms of copper, how many moles of copper do you have?
A) 0.330
B) 3.00
C) 0.750
D) 2.00
C
_____23. How many atoms of lithium are in 11.8 g of Li?
A) 1.35 x 1024
B) 1.70 x 1024
C) 1.02 x 1024
D) 2.22 x 1024
D
_____ 24. How many moles of oxygen are in 3.70 moles of NaClO4?
A) 3.70
B) 0.270
C) 21.5
D) 14.8
C
_____25. What is the mass percent of Mg in magnesium chloride (MgCl2)?
A) 12.3
B) 40.7
C) 25.6
D) 68.3
D
_____26. When the equation, ___O2 + ___C5H12 → ___CO2 + ___H2O is balanced, the coefficient:
of O2 is:
A) 3
B) 4
C) 5
D) 8
B
_____ 27. What are the coefficients for the following reaction when it is properly balanced?
___Na3PO4 + ___Ba(NO3)2 → ___NaNO3 + ___Ba3(PO4)2
A) 2, 1, 1, 3
B) 2, 3, 1, 6
C) 2, 3, 6, 1
D) 6, 1, 3, 2
B
_____28. What are the coefficients for the following reaction when it is properly balanced?
___nitrogen monoxide (g) + ___carbon monoxide (g) → ___nitrogen (g) +___carbon dioxide (g)
A) 2, 1, 1, 2
B) 2, 2, 1, 2
C) 2, 2, 2, 1
D) 1, 1, 2, 2
D
_____29. Sodium metal reacts with water to form aqueous sodium hydroxide and hydrogen gas. Which
equation below best describes this reaction?
A) Na + H2O → NaOH (aq) + H (g)
B) S + H2O → SOH (aq) + H (g)
C) Na + H2O → NaOH (aq) + H2 (g)
D) 2Na + 2H2O → 2NaOH (aq) + H2 (g)
CHAPTER 8 QUESTIONS:
C
_____30. How many moles of H2 can be made from complete reaction of 3.0 moles of Al?
Given: 2 Al + 6 HCl → 2 AlCl3 + 3 H2
A) 3 moles
B) 3.0 moles
C) 4.5 moles
D) 9.0 moles
D
_____31. How many moles of sodium metal are needed to make 3.6 moles of sodium chloride?
Given the reaction: 2Na + Cl2 → 2NaCl
A) 0.9
B) 7.2
C) 1.8
D) 3.6
D
_____32. Given the balanced equation CO2 + Si → SiO2 + C, if you were to react 1 mole of CO2 with
1 mole of Si, which statement is TRUE?
A) The CO2 is the limiting reactant.
B) The Si is the limiting reactant.
C) The SiO2 is the limiting reactant. D) You have equal stoichiometric amounts of reactants.
B
_____33. The theoretical yield of a reaction is 75.0 grams of product and the actual yield is 42.0g. What
is the percent yield?
A) 75.0
B) 56.0
C) 31.5
D) 178
B
_____34. Consider the following reaction: 2 Mg + O2 → 2 MgO △H rxn = -1203 kJ
Calculate the amount of heat (in kJ) associated with complete reaction of 4 moles of Mg.
A) -1203 kJ
B) -2406 kJ
C) -601.5 kJ
D) -4812 kJ
Section 2 - Answer the following computational questions using the information provided. You
must show a plan for your calculations, along with the conversion factors involved for full credit .
Write your answer in the box provided. 1. How many atoms of potassium are contained in 3.00 mol of K3PO4?
(Avogadro’s number = 6.022 x 1023)
Plan and Calculations:
3.00 mol
K3PO4
x
3.00 mol K
1.00 mol K3PO4
23
x 6.022 x 10 K atoms = 5.42 x 1024 K atoms
1.00 mol K
2. How many moles of calcium phosphate are in 50.00 g of Ca3(PO4)2?
(atomic weights: Ca, 40.08; P, 30.97; O, 16.00)
Molar Mass Calculation:
3(40.08) + 2(30.97) + 8(16.00) = 310.18
Plan and Calculations:
50.00 g Ca3(PO4)2
x
1.00 mol Ca3(PO4)2
310.18 g Ca3(PO4)2
= 0.1612 mol Ca3(PO4)2
3. How many moles of carbon are contained in 100.00 g of Pb(CO3)2?
(atomic weights: Pb, 207.20; C, 12.01; O, 16.00)
Molar Mass Calculation:
207.20 + 2(12.01) + 6(16.00) = 327.22
Plan and Calculations:
100.00 g Pb(CO3)2
x
1.00 mol Pb(CO3)2
327.22 g Pb(CO3)2
x
2.00 mol C
1.00 mol Pb(CO3)2
= 0.6112 mol C
4. How many grams of sodium are contained in 15.00 g of NaHCO3 (molar mass = 84.01)?
Plan and Calculations:
15.00 g NaHCO3
x
1.00 mol NaHCO3
84.01 g NaHCO3
or
x
x
= 4.105 g mol Na
22.99 g Na
1.00 mol Na
x
1.000 mol
1.00 mol NaHCO3
22.99 g Na
84.01 g NaHCO3
5. How many moles of NH3 can theoretically be produced by the reaction of
2.00 g of N2 with 3.00 g H2? (Molar masses: N2, 28.02; H2, 2.02)
Reaction: N2(g) + 3 H2(g) → 2 NH3(g)
2.00 g N2
1.00 mol N2
28.02 g N2
x
2.00 mol NH3
1.00 mol N2
x
= 0.143 mol NH3
3.00 g H2
x
1.00 mol H2
2.02 g H2
x
2.00 mol NH3
3.00 mol H2
= 0.990 mol NH3
6. In the following reaction, if you start with 42.0 g of CO2 and 99.9 g KOH, which is the limiting reactant? (Molar masses: CO2, 44.01; KOH, 56.11)
Reaction: CO2 + 2KOH → K2CO3 + H2O
42.0 g CO2
x
1.00 mol CO2
44.01 g CO2
x
1.00 mol KOH
56.11 g KOH
x
1.00 mol K2CO3 (or H2O)
1.00 mol
99.9 g
KOH
x
= 0.954 mol
1.00 mol K2CO3 (or H2O)
2.00 mol KOH
= 0.890 mol
7. If you start with 15.5 g of Na2S and 12.1 g CuSO4 and produce only 3.05 g of CuS, what is the percent yield of CuS for the following reaction? (Molar masses: Na2S, 78.05; CuS, 95.62;
CuSO4, 157.62)
Reaction: Na2S + CuSO4 → Na2SO4 + CuS
15.5
g Na2S
x
1.00 mol Na2S
78.05 g Na2S
x
1.00 mol CuS
1.00 mol Na2S
x
12.1
g CuSO4
95.62 g CuS g Na
1.000 mol CuS
= 18.99 g CuS
x 1.00 mol CuSO4
157.62 g CuSO4
x
1.00 mol CuS
1.00 mol CuSO4
x
95.62 g CuS g Na
1.000 mol CuS
= 7.340 g CuS
(3.05/7.34) x 100 = 41.6%