Q1. 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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Q2. What is the molarity of a solution prepared by dissolving 5 grams of NaCl in enough water to make 250 mL of solution? (Molar mass of NaCl = 58.5 g/mol) (2023)
Solution:
Molarity (M) = moles of solute / liters of solution. Moles of NaCl = 5 g / 58.5 g/mol = 0.0855 moles. Volume of solution = 250 mL = 0.250 L. M = 0.0855 moles / 0.250 L = 0.342 M, approximately 0.34 M.
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Q3. If 10 g of sugar (C12H22O11) is dissolved in 200 g of water, what is the mass percentage of the 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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Q4. 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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Q5. If 10 g of sugar is dissolved in 100 g of water, what is the mass percent of sugar in the solution? (2023)
Solution:
Mass percent = (mass of solute / total mass of solution) x 100. Total mass = 10 g + 100 g = 110 g. Mass percent = (10 g / 110 g) x 100 = 9.09%, approximately 10%.
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Q6. What is the volume of 1 M HCl solution needed to obtain 0.5 moles of HCl? (2022)
Solution:
Volume = moles / molarity = 0.5 moles / 1 M = 0.5 L.
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Q7. What is the mass percent of a solution containing 10 g of solute in 90 g of solvent?
Solution:
Mass percent = (mass of solute / total mass of solution) x 100 = (10 g / (10 g + 90 g)) x 100 = 10%
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Q8. 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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Q9. How many liters of a 0.5 M NaOH solution are needed to obtain 1 mole of NaOH? (2023)
Solution:
Volume = moles / molarity = 1 mole / 0.5 M = 2 L.
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Q10. How many liters of a 3 M solution can be made from 6 moles of solute? (2023)
