Osmosis + practical

• What is osmosis?


  The movement of water molecules across a partially permeable membrane
• In which direction do water molecules move during osmosis?


  From a region of high water concentration to a region of low water concentration
• What does it mean that water molecules move both ways during osmosis?


  It indicates that water molecules are constantly moving in and out of the membrane
• What happens when there are more water molecules on one side of a membrane?


  There is a steady net flow of water molecules to the side with fewer water molecules
• What is the process of osmosis characterized by?


  • Movement of water across a partially permeable membrane
  • Direction: high water concentration to low water concentration
  • Continuous movement in both directions
  • Net flow towards fewer water molecules
• The rate of osmosis depends on the surface area, temperature, pressure difference across the membrane, and thickness of the membrane.
• Osmosis is the movement of water molecules from an area of high concentration to low concentration through a partially permeable membrane.
• What is the first step in the osmosis practical involving potatoes?


  Cut potatoes into identical cylinders and place them in beakers of different sugar solutions.
• Why are different sugar solutions used in the osmosis practical?


  To observe the effect of varying concentrations on osmosis.
• What is the range of sugar solution concentrations used in the experiment?

  From pure water to very concentrated sugar solution
• What should be done after leaving the potato cylinders for 24 hours?

  Dry the potatoes with a paper towel and measure the new mass.
• What does an increase in mass of the potato indicate in terms of osmosis?


  Water has entered the potato by osmosis.
• What does a decrease in mass of the potato indicate in terms of osmosis?


  Water has exited the potato by osmosis.
• What are the dependent and independent variables in the osmosis practical?


  • Dependent variable: Mass of the chip
  • Independent variable: Concentration of sugar solutions
• What are the controlled variables in the osmosis practical?


  • Temperature
  • Time
  • Type of sugar
  • Volume
• What error can occur if the potato is not dried before measuring mass?


  Excess water may lead to an increase in mass.
• How can evaporated water affect the experiment?


  It can change the concentration of the sugar solutions.
• How can errors in the osmosis practical be reduced?


  • Repeat the experiment
  • Calculate the mean percentage mass change