Osmosis coursework. The aim of this investigation is to find the best concentration of salt solution to preserve chips in, so there is no net movement of water in or out of the chip.

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Steven bangar 10 blue

Osmosis coursework


Scenario:

Mr Chips runs a busy chip shop. He cuts his chips early in the morning and stores them in water which allows him to quickly fry and serve his chips when it gets too busy at lunch time. Mr Chips asked his son to help him in the chip shop one day. His son John asked his dad why he stored the chips in water before frying them. Mr Chips said “The water stopped them from browning” John informed his dad that by putting potatoes into water caused them to absorb water.  The more water they absorbed the more oil they would take up when they were fried, making them unhealthy.  John told his dad that the potato chips should be stored in salty water so they did not take in or release any water.

Aim:

The aim of this investigation is to find the best concentration of salt solution to preserve chips in, so there is no net movement of water in or out of the chip.

Scientific theory

Diffusion is when particles spread in random motions from places with high concentration to places with low concentration. The particles move in a random motion because they collide frequently. The particles will keep mixing until they are evenly distributed. The concept of diffusion is driven by concentration gradient but diffusion still happens when there is no concentration gradient. The diagram below shows this.

Osmosis is a special type of diffusion involving only water molecules. It is physical process of when water molecules move across a semi permeable membrane (a membrane which allows certain molecules to pass through it by diffusion) from a low solute concentration to a high solute concentration. The diagram below summaries what happens in osmosis.

What happens to potato cells in different concentrations of water?

There are three different solutions potato chips can be placed in. these are hypertonic, hypotonic and isotonic and all three will be discussed below. The diagram on the following page shows what happens to a cell when they are filled with Hypertonic, Hypotonic and Isotonic solution.

Hypertonic solution:

An hypertonic solution is when the solution has more osmosis pressure. This causes the cell to become flaccid.

Hypotonic solution

An hypotonic solution is when the solution lacks osmotic pressure. This causes the cell to become turgid.

Isotonic solution

An isotonic solution is when the solution has equal osmotic pressure. The cell keeps in its original shape

Prediction:

My prediction is that the low concentration solution (0 - 0.4mol/dm3) salt solutions will make the chips turgid because the solution will be hypotonic on the other hand the chips in the concentrated solution (0.6 – 1.0mol/dm3) will make the chips lack in firmness. So I think the 0.5 salt solution would be the best concentration to store the chips in because the solution will not make the chips absorb water nor loose much water because the solution would be isotonic which makes this the perfect concentration to store the chips in.

Preliminary Investigation

The reason I am doing a preliminary report is because if we do anything incorrect we will know where we went wrong and so the main investigation would go perfectly. this would also mean that the results for the main investigation would be more accurate which would result to better quality chips for Mr chips shop. My range is 0.0-1.0mol/dm3 as this allows me to maximise the reliability of my results

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Variables:

Independent variable:  The concentration of salt solution

Dependant variables: There are two dependent variables, these are the length and mass of the chips

Controlled variables:

Apparatus:

Method:

1.   Set up all the equipment

  1. Put on goggles

  1. Make the solution with the salt solution and distilled water

  1. Pour the solution into 5 specimen tubes

  1. Cut the potatoes into halves

  1. Take the cork ...

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