Start by cutting a potato cylinder with the cork borer.
Potato cylinders
No cylinder chosen
Cut a cylinder, or tap one on the tile.
Nothing is soaking yet.
Use one cylinder in each tube. Record the concentration of each solution, the mass of the cylinder before and after, the change in mass (final minus initial, keeping the sign) and the percentage change in mass to one decimal place. Choose the unit for each column heading.
| concentration/sucrose solution | initial mass/before soaking | final mass/after soaking | change in mass/final minus initial | percentage change/change ÷ initial × 100 |
|---|---|---|---|---|
Plot the percentage change in mass on the y-axis against the concentration on the x-axis. Some values are negative: start the y-axis below zero. Draw a straight line of best fit that crosses the zero line.
Choose a start and a value per large square for both axes, then plot.
Use your graph to find the concentration of sucrose solution that would cause no change in mass. Give the unit.
Explain why the cylinder in 0.0 mol/dm³ (pure water) gained mass.
Why is the percentage change in mass used, rather than the change in mass?
State one source of error in this investigation.
Suggest one improvement to make the results more reliable or more accurate.