Solubility curves
3 marks · EasyA student performed an experiment to measure the solubility of sodium nitrate. Her results are:
| Mass of evaporating dish (g) | Mass of dish + solution (g) | Mass of dish + dry sodium nitrate (g) |
|---|---|---|
| 22.00 | 60.00 | 32.50 |
Calculate the mass of sodium nitrate dissolved in the solution.
Calculate the mass of water in the solution.
Calculate the solubility of sodium nitrate in g per 100 g of water.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 10.5 g
(b) 27.5 g
(c) 38.2 g per 100 g water
Common mistakes: Wrong subtraction order; Forgetting to multiply by 100
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Subtracts mass of dish from mass of dish + dry sodium nitrate: 32.50 – 22.00 = 10.50 g
M2 (b) · 1 mark · Subtracts mass of dish + dry sodium nitrate from dish + solution: 60.00 – 32.50 = 27.50 g
A1 (c) · 1 mark · Solubility calculated as 10.5 / 27.5 x 100 = 38.2 g per 100 g water (follow-through)
Worked solution
a) Mass of sodium nitrate = 32.50 – 22.00 = 10.50 g
b) Mass of water = 60.00 – 32.50 = 27.50 g
c) Solubility = (10.50 ÷ 27.50) × 100 = 38.18 ≈ 38.2 g per 100 g of water