B1 - osmosis

• • Osmosis is the movement of water across a partially permeable membrane from high to low concentration
• 1. Cut up potato into identical cylinders and place them in beakers with different sugar solutions - one should be water and another should be very concentrated sugar solution
• 2. Measure the mass of the cylinders and leave them for 24 hours
• 3. Take them out, dry them and measure the masses again.
• 4. If the cylinder has increased in mass, water has been drawn in by osmosis - if the cylinder has decreased in mass, water has been drawn out
• • Percentage change can be calculated in mass
  • Percentage change = final - original/original x 100
• • The dependent variable is the chip mass
  • The independent variable is the concentration of the sugar solution
  • Control variables are: temperature, time, volume of solution
• ERRORS:

  • Cylinders were not fully dried - would increase mass
  • Water evaporated from beakers - concentration of sugar would change
  • Effect can be reduced by repeating experiment and calculating mean percentage change