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Plotting osmosis investigation results
A student investigated the concentration of salt in solution Z using osmosis. Table 1 shows the results.
| Concentration of salt solution in mol/dm³ | Mass of tube at start in grams | Mass of tube after 2 hours in grams | Change in mass in grams | Percentage (%) change in mass |
|---|---|---|---|---|
| 0.0 | 15.54 | 16.50 | 0.96 | X |
| 0.2 | 15.16 | 15.78 | 0.62 | 4.1 |
| 0.4 | 15.00 | 15.35 | 0.35 | 2.3 |
| 0.6 | 15.29 | 15.37 | 0.08 | 0.5 |
| 0.8 | 14.95 | 14.75 | −0.20 | −1.3 |
| 1.0 | 14.77 | 14.40 | −0.37 | −2.5 |
Complete Figure 2. You should:
- plot the percentage change in mass from Table 1 for salt concentrations of only 0.2 mol/dm³ to 1.0 mol/dm³
- draw a line of best fit.
One of the results has been plotted for you.
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Marking points
- 1 Plots at least 3 of the 4 required unplotted points accurately.
- 2 Plots all 4 required unplotted points accurately.
- 3 Draws an appropriate line of best fit.
Why this answer loses marks
Plot every row from the table and join each point to the next.
The task limits which points should be added and requires a line of best fit rather than point-to-point joining.