Q1. What is the mass of solute in grams in a 3 M solution of NaCl in 1 L of solution? (2023)
Solution:
Molar mass of NaCl = 58.44 g/mol; mass = moles × molar mass = 3 moles × 58.44 g/mol = 175.32 g
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Q2. How many liters of a 3 M solution can be made from 6 moles of solute? (2023)
Solution:
Volume = moles / molarity = 6 moles / 3 M = 2 L.
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Q3. If 10 grams of NaCl is dissolved in 500 mL of water, what is the concentration in g/L? (2020)
Solution:
Concentration = (10 g / 0.5 L) = 20 g/L.
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Q4. What is the molarity of a solution containing 5 moles of solute in 2 liters of solution? (2021) 2021
Solution:
Molarity (M) = moles of solute / liters of solution = 5 moles / 2 L = 2.5 M.
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Q5. What is the volume of a 2 M NaOH solution needed to obtain 4 moles of NaOH? (2021) 2021
Solution:
Volume (L) = moles / molarity = 4 moles / 2 M = 2 L.
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Q6. If 10 g of sugar (C12H22O11) is dissolved in 200 g of water, what is the mass percentage of the sugar solution? (Molar mass of sugar = 342 g/mol) (2023)
Solution:
Mass percentage = (mass of solute / mass of solution) x 100. Mass of solution = 10 g + 200 g = 210 g. Mass percentage = (10 g / 210 g) x 100 = 4.76%.
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Q7. What is the effect of increasing the temperature on the solubility of most solid solutes in water? (2023)
Solution:
For most solid solutes, increasing the temperature increases their solubility in water.
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Q8. If 15 g of sugar is dissolved in 300 mL of water, what is the concentration in g/mL? (2020)
Solution:
Concentration = mass / volume = 15 g / 300 mL = 0.05 g/mL.
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Q9. What is the mass of NaOH required to prepare 0.5 L of a 1 M solution? (2023)
Solution:
Molar mass of NaOH = 40 g/mol; grams = moles × molar mass = (1 mole/L × 0.5 L) × 40 g/mol = 20 g
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Q10. What is the freezing point depression of a solution containing 1 mol of NaCl in 1 kg of water? (Kf for water = 1.86 °C kg/mol) (2023)
Solution:
Freezing point depression (ΔTf) = i * Kf * m. For NaCl, i = 2 (dissociates into Na+ and Cl-). m = 1 mol/kg. ΔTf = 2 * 1.86 °C kg/mol * 1 = 3.72 °C.
