Download Unit #7 Take Home Test

Name: ___________________________________________________________________
Period: __________
Unit #7 Take Home Test
The following questions are due on Monday, January 25th at the beginning of class. Failure to turn in the take-home test
on the due date will result in a 20 point reduction from the overall grade for each day the assignment is late.
1. The empirical formula of a compound is CH4.
The molecular formula of the compound could
be
a. CH4
b. C2H6
c. C3H8
d. C4H10
7. What is the percent by mass of oxygen in
Ca(OH)2? [formula mass = 74.1]
a. 21.6%
b. 43.2%
c. 45.9%
d. 54.1%
2. What is the total number of molecules
contained in 0.50 mole of O2 at STP?
a. 6.0 x 1023
b. 4.5 x 1023
c. 3.0 x 1023
d. 1.5 x 1023
8. Which of the following reactions does not
represent a double replacement reaction?
a. Mg(s) + 2HCl(aq) MgCl2(s) + H2(g)
b. HCl(aq) + KOH(aq) KCl(aq) + H2O(ℓ)
c. Pb(NO3)2(aq) + CaCl2(aq) Ca(NO3)2(aq) + PbCl2(s)
d. 2KClO3(s) 2KCl(s) + 3O2(g)
3. In the reaction Al + Cr3+ Al3+ + Cr, the
reducing agent is
a. Al
b. Cr3+
c. Al3+
d. Cr
9. What is the total number of moles of atoms
contained in 1 mole of NH3?
a. 1 mole
b. 2 moles
c. 3 moles
d. 4 moles
4. According to the equation
HCl + NaOH NaCl + H2O,
the total number of moles of HCl that can be
neutralized by 80. grams of NaOH is
a. 1.0
b. 2.0
c. 36
d. 72
10. The gram-formula mass of (NH4)2CO3 is
a. 46.0 g/mol
b. 64.0 g/mol
c. 78.0 g/mol
d. 96.0 g/mol
5. When the equation Al(s) + O2(g) Al2O3(s) is
correctly balanced using smallest whole
numbers, the sum of the coefficients will be
a. 9
b. 7
c. 3
d. 12
6. A sample of a substance containing only
magnesium and chlorine was tested in the
laboratory and was found to be composed of
74.5% chlorine by mass. If the total mass of the
sample was 190.2 grams, what was the mass of
the magnesium?
a. 24.3 g
b. 48.5 g
c. 70.9 g
d. 142 g
11. Which metal can replace Cr in Cr2O3?
a. nickel
b. lead
c. copper
d. aluminum
12. A compound has the empirical formula CH2O
and a gram-formula mass of 60 grams per mole.
What is the molecular formula of this
compound?
a. CH2O
b. C2H4O2
c. C3H8O
d. C4H8O4
13. In the reaction Mg + Cl2 MgCl2, the correct
half-reaction for the oxidation that occurs is
a. Mg + 2e- Mg2+
b. Cl2 + 2e- 2Clc. Mg Mg2+ + 2ed. Cl2 2Cl- + 2e-
14. Given the balanced equation representing a
reaction: 2CO(g) + O2(g) 2CO2(g).
What is the mole ratio of CO(g) to CO2(g) in this
reaction?
a. 1:1
b. 1:2
c. 2:1
d. 3:2
21. A student observed the following reaction:
AlCl3(aq) + 3NaOH(aq) Al(OH)3(s) + 3NaCl(aq)
After the products were filtered, which
substance remained on the filter paper?
a. NaCl
b. NaOH
c. AlCl3
d. Al(OH)3
15. Given the reaction:
3Cu + 8HNO3 3Cu(NO3)2 + 2NO + 4H2O
The total number of grams of Cu needed to
produce 2.0 mole of Cu(NO3)2 is
a. 32
b. 64
c. 128
d. 192
22. Given the incomplete equation: 4Ni + 3O2 2X
Which compound is represented by X?
a. NiO
b. Ni2O3
c. Ni3O2
d. Ni3O4
16. A compound consists of 46.7% nitrogen and
53.3% oxygen by mass. What is its empirical
formula?
a. NO
b. NO2
c. N2O
d. N2O3
17. A 1.20-gram sample of a hydrated salt is heated
to a constant mass of 0.80 gram. What is the
percent by mass of water in the original
sample?
a. 20
b. 33
c. 50
d. 67
18. When a substance is reduced, it
a. loses protons
b. gains protons
c. acts as an oxidizing agent
d. acts as a reducing agent
19. According to Reference Table J, which reaction
will take place spontaneously?
a. I2 and CaF2
b. Cl2 and CaF2
c. F2 and CaCl2
d. I2 and CaCl2
20. What is the total number of oxygen atoms in
the formula MgSO4 • 7H2O? [The • represents
seven units of H2O attached to one unit of
MgSO4.]
a. 11
b. 7
c. 5
d. 4
23. Given the balanced equation representing a
reaction: PbSO4 + Mg MgSO4 + Pb
Which type of chemical reaction is represented
by this equation?
a. double replacement
b. single replacement
c. decomposition
d. synthesis
24. Which statement describes the composition of
potassium chlorate, KClO3?
a. The proportion by mass of elements
combined in potassium chlorate is
fixed.
b. The proportion by mass of elements
combined in potassium chlorate varies.
c. Potassium chlorate is composed of four
elements.
d. Potassium chlorate is composed of five
elements.
25. If a chemical equation is balanced properly,
both sides of the equation must have the same
number of
a. atoms
b. coefficients
c. molecules
d. subscripts
26. Given the reaction:
Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g)
Which statement correctly describes what
occurs when this reaction takes place in a closed
system?
a. Atoms of Zn(s) lose electrons and are
oxidized.
b. Atoms of Zn(s) gain electrons and are
reduced.
c. There is a net loss of mass.
d. There is a net gain of mass.
27. Given the unbalanced equation:
___ Mg(ClO3)2(s) ___ MgCl2(s) + ___ O2(g)
What is the coefficient of O2 when the equation
is balanced correctly using the smallest whole
number coefficients?
a. 1
b. 2
c. 3
d. 4
28. According to Reference Table F, which of these
compounds is the least soluble in water?
a. K2CO3
b. KC2H3O2
c. Ca3(PO4)2
d. Ca(NO3)2
29. A sample of a compound contains 65.4 grams of
zinc, 12.0 grams of carbon, and 48.0 grams of
oxygen. What is the mole ratio of zinc to carbon
to oxygen in this compound?
a. 1:1:2
b. 1:1:3
c. 1:4:6
d. 5:1:4
30. According to Reference Table J, which of these
metals will react most readily with 1.0 M HCl to
produce H2(g)?
a. Ca
b. K
c. Mg
d. Zn
31. The unbalanced equation below represents the decomposition of potassium chlorate.
KClO3(s) KCl(s) + O2(g)
a. Balance the equation, using the smallest whole-number coefficients. [1]
b. Explain, in terms of particles, why the KCl(s) produced in this reaction does not conduct electricity. [1]
c. Calculate the mass percentage of oxygen in potassium chlorate. [1]
32. A student takes 1.082 grams of hydrated nickel (II) sulfate and heats it in a crucible.
NiSO4•xH2O(s) NiSO4(s) + xH2O(g)
The anhydrous material weighed 0.596 grams.
a. Determine the complete formula for this hydrated salt. Show all work. [2]
b. Write the IUPAC name for the hydrated crystal. [1]
33. Base your answers to the following questions on the unbalanced redox reaction below.
Cu(s) + AgNO3(aq) Cu(NO3)2(aq) + Ag(s)
a. Balance the redox equation, using the smallest whole-number coefficients. [1]
b. Write a balanced net ionic equation. [1]
c. Write the reduction half-reaction. [1]
34. Naphthalene, a nonpolar substance that sublimes at room temperature, can be used to protect wool clothing
from being eaten by moths.
a. Explain why naphthalene is not expected to dissolve in water. [1]
b. The empirical formula for naphthalene is C5H4 and the molecular mass of naphthalene is 128
grams/mole. What is the molecular formula for naphthalene? [1]
35. A hydrated compound contains water molecular within its crystal structure. The percent composition by mass of
water in the hydrated compound CaSO4•2H2O has an accepted value of 20.9%. A student did an experiment and
determined that the percent composition by water in CaSO4•2H2O was 21.4%.
Calculate the percent error of the student’s experimental result. Your response must include both a correct
numerical setup and the calculated result. [2]
36. An unsaturated solution is made by completely dissolving 20.0 grams of NaNO3 in 100.0 grams of water at 20.0°C.
Calculate the number of moles of NaNO3 used to make this unsaturated solution. [2]
37. Rust on an automobile door contains Fe2O3(s). The balanced equation representing one of the reactions between
iron in the door of the automobile and oxygen in the atmosphere is given below.
4Fe(s) + 3O2(g) 2Fe2O3(s)
a.
b.
c.
d.
Identify the type of chemical reaction represented by this equation. [1]
Determine the gram-formula mass of the product of this reaction. [1]
Write the IUPAC name for Fe2O3. [1]
If 9.0 moles of O2 are completely consumed, what is the mass of Fe2O3 produced? [2]
38. Aqueous solutions of lithium chromate and barium chloride are mixed together and a yellow precipitate is
formed.
a. Write the balanced chemical equation for this reaction, including the products formed. [1]
b. Using the Solubility Guidelines on the Chemistry Reference Table, determine which of the products
formed is the precipitate. [1]
c. Write the net ionic equation for this reaction. [1]
d. Identify the spectator ion(s). [1]