RP Osmosis

• What should be prepared for the osmosis practical?


  Samples of potatoes or other plant tissue
• What measurements should be taken before and after soaking the potato samples?

  Mass and length of the samples
• How is the percentage change in mass calculated in the osmosis practical?


  By comparing the mass before and after soaking
• What is the independent variable in the osmosis practical?


  The concentration of salt or sucrose solution in mol dm³
• What are the dependent variables in the osmosis practical?


  The mass and length of each potato cylinder before and after immersion
• What does a positive percentage change in mass indicate in the osmosis experiment?


  That the potato has gained water by osmosis
• What does a negative percentage change in mass suggest in the osmosis experiment?


  That the potato has lost water to the surrounding solution
• What does it mean when the results lie above 0 on the X-axis in the osmosis graph?


  It means the potato has increased in mass and taken in water
• What does it mean when the line crosses the X-axis in the osmosis graph?


  It indicates the concentration of sugar/salt inside the potato where no water has been lost or gained
• What is an important control variable in the osmosis practical?


  The type and volume of solute in the solution