The aim of this lab is to use an artificial partially permeable membrane to replicate osmosis by filling three different bags

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Lab Osmosis

Introduction

Osmosis is the net movement of water molecules through a partially permeable membrane, from their high water concentration to their low, this process occurs in a cell when the concentration of water molecules is higher inside the cell then outside, this means that the solution is hypertonic, which means that the water molecules will move outwards until they achieve equilibrium, but the water can also move inside the cell when the solution is hypotonic which means that there is a lower water concentration inside the cell then outside, so the water molecules will move inside the cell until it reaches equilibrium, when the solutions both inside the cell and outside the cell are of equal concentration the solution is called isotonic. The aim of this lab is to use an artificial partially permeable membrane to replicate osmosis by filling three different bags of this partially permeable membrane (in this case dialysis tubing) with three different concentration of sugar-water solution.

Material

  1. 8 pieces of string
  2. 4 water soaked dialysis tubing about 15 cm long
  3. Graded cylinder or mechanical pipette
  4. 1% sucrose solution
  5. 25% sucrose solution
  6. 50% sucrose solution
  7. 1000ml beaker
  8. Large bowl
  9. Scale (±0.01 g)
  10. Timer (±1s)

Hypothesis

I expect that bag A will lose mass due to the fact that the water concentration outside the bag is lower than the water concentration inside which means that the water molecules will move outwards to try and achieve equilibrium, bag B I assume nothing will happen to it i.e. it will not lose any mass. And bag C and D will increase in mass, but bag D will increase in mass more than bag C because the concentration of solutes is higher inside the cell than outside so the water will move inwards to balance the concentration out.  

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Procedure

Firstly we took the pieces of string and we used them to seal one end of the dialysis tubing then we took small pieces of paper and wrote respective letter on them (A, B, C and D) for identification purposes then filled the bags with their respective water-sucrose solutions (A 10ml of 1% sucrose, B 10ml 1% sucrose, C 10ml 25% sucrose and D 10 ml 50% sucrose). And we checked for leaks then we took firstly the 1000ml beaker and we filled it with 50% sucrose solution and dipped bag A in it started the timer and waited ...

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