Solubility curves
4 marks · NormalThe table below shows the solubility of lithium nitrate at different temperatures.
| Temperature /°C | Solubility /g per 100 g water |
|---|---|
| 10 | 46.0 |
| 30 | 62.0 |
| 50 | 78.5 |
| 70 | 94.0 |
| 90 | 110.0 |
Plot a solubility curve for lithium nitrate using the data in the table. Label both axes.
Describe the shape of the solubility curve you draw.
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) Correctly plotted curve with both axes labelled; all data points correctly plotted and a smooth best fit line or curve through them. · must show Points at (10, 46), (30, 62), (50, 78.5), (70, 94), (90, 110), x-axis: Temperature (°C), y-axis: Solubility (g per 100 g water), Smooth curve joining points
(b) The solubility curve rises smoothly and steadily as temperature increases; it is an upward sloping curve. · must show States that solubility increases with temperature, Describes the upward curve or slope
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Plots all 5 data points correctly on graph.
B2 (a) · 1 mark · Draws a smooth best-fit curve or line and labels axes with units.
B3 (b) · 1 mark · States that solubility increases as temperature increases or the curve rises.
B4 (b) · 1 mark · Describes the shape clearly as a curve, upward slope, or mentions the increase is steady or non-linear.
Worked solution
a) Mark the points for each temperature and solubility on your graph. Join them with a smooth curve. Label the x-axis as 'Temperature (°C)' and the y-axis as 'Solubility (g per 100 g water)'.
b) The curve starts lower and rises smoothly as temperature increases, showing that the solubility of lithium nitrate increases steadily with temperature.