An Investigation of Factors Affecting the Rate of Osmosis

An Investigation of Factors Affecting the Rate of Osmosis

Introduction

Osmosis is the movement of water molecules across a semi permeable

membrane from a region of high water concentration to a region of low

water concentration.

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A semi permeable membrane is a membrane with very small holes in it;

they are so small that only water molecules can pass through them.

Bigger molecules such as glucose cannot pass through it. In actual

fact water molecules pass both ways through the membrane, but because

there are more water molecules in the high concentration region than

the other there is a steady net flow into the lower concentration

region. The lower concentration is the stronger solution, such as a

glucose solution. This movement causes the glucose-rich region to fill

up with water. The water movement is diluting the solution so that the

concentration on both sides is equal.

Osmosis

Figure no.1

This diagram illustrates the net flow of water movement from a

hypotonic solution, low solute concentration, to an area of high

solute concentration. In other words this shows water movement across

the semi permeable membrane from a high concentration of water to a

low concentration of water.

Water moves from a high water potential to a low water potential. A

low water potential is a high solute concentration. Water potential

has the symbol Ψ, sigma.

When water potential on both sides is equal then it is known as

equilibrium. In this case there is not an absence of movement between

the equal water potentials but a movement of water in both directions,

maintaining the equilibrium. Osmosis is a continuous process which

does not require any energy to take place.

Factors Which Affect the Rate of Osmosis

1) Temperature: The higher the temperature is the faster the molecules

will move. This means that the movement of water molecules across the

semi permeable membrane will be faster.

2) Surface Area: When there is a larger surface area there will be