Q. What is the volume percent concentration of a solution containing 30 mL of ethanol in 150 mL of solution?
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A.
20%
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B.
25%
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C.
30%
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D.
15%
Solution
Volume percent = (volume of solute / total volume) x 100 = (30 mL / 150 mL) x 100 = 20%.
Correct Answer: B — 25%
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Q. What is the volume percent of ethanol in a solution made by mixing 30 mL of ethanol with 70 mL of water?
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A.
30%
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B.
70%
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C.
50%
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D.
20%
Solution
Volume percent = (volume of solute / total volume) × 100 = (30 mL / (30 mL + 70 mL)) × 100 = 30%.
Correct Answer: A — 30%
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Q. Which of the following is a correct unit for concentration?
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A.
Molarity
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B.
Molality
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C.
Mass percent
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D.
All of the above
Solution
All listed options are valid units for concentration.
Correct Answer: D — All of the above
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Q. Which of the following is a correct unit for molality?
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A.
mol/L
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B.
mol/kg
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C.
mol/mL
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D.
mol/1000g
Solution
Molality is defined as moles of solute per kilogram of solvent, hence the unit is mol/kg.
Correct Answer: B — mol/kg
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Q. Which of the following is a unit of concentration that expresses the amount of solute per volume of solution?
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A.
Molarity
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B.
Molality
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C.
Mole fraction
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D.
Normality
Solution
Molarity is defined as moles of solute per liter of solution.
Correct Answer: A — Molarity
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Q. Which of the following is the correct unit for molality?
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A.
mol/L
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B.
mol/kg
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C.
mol/mL
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D.
mol/1000g
Solution
Molality is defined as moles of solute per kilogram of solvent, hence the unit is mol/kg.
Correct Answer: B — mol/kg
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Q. Which of the following is the correct unit for molarity?
-
A.
mol/L
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B.
mol/kg
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C.
g/L
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D.
g/mol
Solution
Molarity is defined as moles of solute per liter of solution, hence the unit is mol/L.
Correct Answer: A — mol/L
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Q. Which of the following solutions has the highest concentration?
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A.
0.1 M NaCl
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B.
0.2 M KCl
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C.
0.05 M CaCl2
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D.
0.3 M MgSO4
Solution
Concentration in terms of molarity: 0.1 M NaCl = 0.1, 0.2 M KCl = 0.2, 0.05 M CaCl2 = 0.15 (0.05*3), 0.3 M MgSO4 = 0.3. Highest is 0.3 M MgSO4.
Correct Answer: D — 0.3 M MgSO4
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Q. Which of the following statements about molarity is true?
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A.
It changes with temperature.
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B.
It is independent of temperature.
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C.
It is defined as moles of solute per liter of solvent.
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D.
It is always equal to molality.
Solution
Molarity is defined as moles of solute per liter of solution, and it can change with temperature due to volume changes.
Correct Answer: A — It changes with temperature.
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