Osmosis is defined as, diffusion, or net movement, of free water molecules from high to low concentration through a semi-permeable membrane. When a substance, such as sugar (which we will be using in the experiment we are about to analyse), dissolves in water, it attracts free water molecules to itself, and in doing so, stops them from moving freely.
The effect of this, is that the concentration of (free) water molecules in that environment goes down. There are less free water molecules, and therefore less water molecules to pass across a semi-permeable membrane, through which sugar molecules and other molecules attached to them are too big to diffuse across with ease.
In the diagram below on the right, we see two solutions divided by a partially/selectively permeable membrane (i.e. one that is porous, but allows water molecules through faster than dissolved substances).
Text Box: Originally, the two solutions were; pure water, on the left, and sugar solution with a high sugar concentration, on the right. The pure water solution is said to have higher water potential than the concentrated sugar solution, because the water will flow from the area of high concentration of free water molecules (the dilute solution), to the area of low concentration of free water molecules (the concentrated solution). In other words, to the sugar solution.
However, in this diagram we see that osmosis has been taking place for a short while, because water molecules have started to diffuse to the right, across the membrane, so that there are now many present on the right side of the membrane, and a few sugar molecules are starting to diffuse across the membrane in the opposite direction, to the left side of the membrane as we see it.
Through moving from an area of lots of free water molecules, to an area where there are less, the sugar concentration (or, ratio of sugar to water molecules) on the left side will increase, and that on the right side will decrease, until they come to a point where the concentrations on either side of the membrane are equal. At this point of equilibrium, the diffusion across the membrane will stop, due to there not being an area of higher or lower concentration.
Factors affecting Rate of Osmosis:
Before I start thinking about what I am going to test in my experiment, and how I am going to carry it out, I have to know the range of factors that might influence these choices. There are several factors that could change the rate of osmosis, but I have to identify, and thenceforth concentrate, on the most important:
· Temperature affects osmosis, because the greater the temperature, the greater the energy (which must be heat), the faster the molecules under the influence of…