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  • Level: GCSE
  • Subject: Science
  • Essay length: 3918 words

'Investigating how isotonic, hypertonic and hypotonic solutions affects the total mass of a potato chip".

Extracts from this essay...

Introduction

OSMOSIS IN POTATO CHIPS 'Investigating how isotonic, hypertonic and hypotonic solutions affects the total mass of a potato chip" Aim: To find out how changing the concentration of salt solution affects the total mass of potato chips, placed in it. So we are investigating the movement of Osmosis through a selectively permeable membrane, in this case potato. Introduction: I am carrying out an investigation regarding Osmosis in potato chips. In order to conduct my investigation I will need to fully understand all the background information I know. Using secondary sources such as textbooks, CD Roms, library, class notes and the Internet. Key words: Isotonic: The solutions being compared have equal concentrations of solutes. E.g. 20ml water + 20ml salt sol. Hypertonic: The solution with the higher concentration of solutes. Hypotonic: The solution with the lower concentration of solutes. Osmotic pressure: Diffusion of water across a membrane - osmosis generates a pressure called Osmotic pressure. Osmolarity: Used to describe the number of solute particles in a volume of fluid. Plants in general Plants need water to grow. Plants use water to aid them in respiration and photosynthesis. So somehow they need to take it up from the environment surrounding them. They do this using the small hair-like fibres on the roots. These hairs sense water and then the water is drawn up through the Xylem and Phloem cells in the shoot of the plant and distributed around the plant to where it is needed. Why plants need water The transpiration stream is the process by which water moves through a plant. Plant cell Why do plants need water? * To keep the leaves cool. * To transport material - Minerals e.g. Magnesium, Nitrogen, * In Photosynthesis to produce Glucose. * To keep cells firm and the plant rigid. * Supports the plant. Osmosis Osmosis is a type of diffusion. It is the movement of water through a semi permeable membrane, separating solutions of different concentrations.

Middle

Method: After having done our preliminary work we knew exactly which measurements we needed to change or keep the same in order to obtain the correct sorts of results. We set up 9 test tube experiments in order to save time. 1. Collect all equipment as listed above. 2. Using the cork borer push it into the middle of the potato. Pull out the cork borer and use the plastic rod to push out the potato. Do this on a tile to avoid scratches. You will need a total of 9 potato chips. 3. Then cut all the potatoes to the same length and make sure you cut off the skin. 4. Weigh each of the potatoes cut to exact mass. 1.99grams 5. Finally double check that all the potatoes are the same in length, diameter etc to ensure a fair reliable test. 6. Collect 9 test tubes and fill them with a total of 40ml of solution, (Different ratios of water and salt solution) 7. Place each potato chip into each of the test tubes at exactly the same time and start the timer. 8. The potatoes should be in the solution for exactly 30min. 9. After 30min take out ALL the potato chips (and exactly the same time), pat it dry and weigh its new mass and record the results on the table. 10. Conduct this experiment at least 3 times and then work out an average. Safety: It is very important when doing any scientific experiment to make sure you abide by the safety rules. In this particular investigation I must make sure of the following: * Keep unnecessary items (e.g. Bags, chairs) away from desk/area of experiment. * Cut each potato chip on a tile using a scalpel, so that no one will be cut. * Be extra careful when handling water, as it may spill and someone could have a nasty accident.

Conclusion

Because according to the particle theory which states that a high temp. Results in particles have more energy therefore more successful collisions. Which means that osmosis will occur faster. And therefore vice versa. In all three of my experiments I used different sizes of test tubes. This could have affected my results because according to the particle theory the particle would have more surface area, therefore there would be more successful collisions. So the larger the surface area the faster the rate of osmosis. I should have used the same sized test tube all throughout each experiment. But didn't because of the lack of test tubes available to us. In order to investigate 'osmosis' more fully, I could conduct the experiment again with the following changes. To investigate different aspects of osmosis. I could extend my coursework by using different solutions. For instance sugar, coffee or even a vimto solution. This will enable me to find out whether osmosis occurs differently according to the solution. I could also use different varieties of potatoes to see whether which brand of potato has the most osmosis occurring within it. I could investigate osmosis occurring in different type of vegetables. I could conduct this experiment using different temperatures (classroom temp, solution temp), to see how temperature affects osmosis. I could use different sizes of potato chips. E.g. I could change the surface area, length, diameter, and total mass. I could start the experiment off with different water potentials for the potato chip. I could use different amounts of the total volume of solution. To see how osmosis affects the amount of solution surrounding it. I could use different light intensities to see whether there is a relationship between light and osmosis. I could run my experiment for different lengths of time to see how much osmosis occurs in a given time. Factors, which may have affected my final results: Size of test tube differed Salt solution Type of potato used Size of potato Mass/ length of potato Amount of solution used Type of water used Environment - light, water, carbon dioxide,

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