CHM 141- Exam 2

Name: ________________________ Class: ___________________ Date: __________ ID: A


Midterm 2 sample

Constants and equations:
Avogadro's number: NA = 6.0221×1023 mol-1
log(10x) = x pH = -log[H+]
Molarity M = mol / V mol = M × V
percent yield = actual yield / theoretical yield × 100%




Multiple Choice (5 pts each)
Identify the choice that best completes the statement or answers the question.

1. When propane undergoes complete combustion, the products are carbon dioxide and water.
__ C3H8(g) + __ O2(g)  __ CO2(g) + __ H2O(g)
What are the respective coefficients when the equation is balanced with the smallest whole numbers?
a. 1, 1, 1, 1
b. 1, 3, 1, 3
c. 1, 3, 3, 1
d. 1, 5, 3, 4
e. 2, 5, 3, 4

2. Which of the following statements is/are CORRECT?
1. All ionic compounds that are soluble in water are electrolytes.
2. All ionic compounds dissolve in water.
3. Molecular compounds are never soluble in water.

a. 1 only
b. 2 only
c. 3 only
d. 1 and 2
e. 2 and 3

3. Which of the following compounds is a weak base?
a. NaOH
b. H2CO3
c. NaCl
d. NH3
e. CH3CO2H


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, Name: ________________________ ID: A


4. How many moles of sodium bromide can be produced from the reaction of 1.50 moles of sodium with 0.950 moles
of bromine gas?
2 Na(s) + Br2(g)  2 NaBr(s)
a. 0.650 mol
b. 1.08 mol
c. 1.50 mol
d. 2.06 mol
e. 0.515 mol

5. How many liters of 0.2207 M KCl(aq) contain 0.333 mol of KCl?
a. 0.277 L
b. 0.903 L
c. 3.71  103 L
d. 1.51 L
e. 5.94  104 L

6. If 25.00 mL of 1.50 M HCl(aq) is diluted with water to a volume of 250.0 mL, what is the molarity of the diluted
HCl(aq)?
a. 1.50  101 M
b. 5.00  102 M
c. 2.07  103 M
d. 4.50  101 M
e. 1.35  103 M

7. A 25.00 mL sample of NaOH is titrated with 30.25 mL of 0.1250 M HCl(aq). What is the concentration of the
NaOH solution?
a. 1.995  104 M
b. 0.09149 M
c. 0.1830 M
d. 0.1513 M
e. 0.08945 M

8. The reaction of tetraphosphorus decaoxide with water produces phosphoric acid.
__ P4O10 + __ H2O  __ H3PO4
What are the respective coefficients when the equation is balanced with the smallest integer values?
a. 1, 1, 1
b. 1, 3, 1
c. 2, 4, 1
d. 2, 6, 2
e. 1, 6, 4

9. All of the following compounds are insoluble in water except ____.
a. BaCO3
b. PbI2
c. Fe(OH)3
d. NH4Cl
e. PbCl2




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