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Water Potential Investigation

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Introduction

Water Potential Investigation Planning the Investigation I am going to find out whether the weight of potato cylinders increases or decreases when placed in strong and weak salt solutions and left for 48 hours, during these 48 hours the water molecules will diffuse from areas of high concentration to low concentration. I predict that the stronger the salt solution, the lighter the potato cylinder will be after 48 hours. I think this will happen because the salt solution has a very low water potential and the potato cylinder will have substantially higher water potential than the salt solution around it. As I will now explain, then water molecules diffuse from the potato cylinder to the salt solution; this makes the potato cylinder a great deal lighter as well. This is all due to high and low water potential. Water molecules move about rapidly from one location to another. The greater the concentration of water molecules in a system, the higher the so-called "water potential". The stronger the salt solution, the lower the water potential, and pure water has the highest water potential. ...read more.

Middle

The factor that I am changing is the strength of the salt solutions, and I am keeping the weight of the potato cylinders the same, all of them will be 1 gram. I will measure out the salt solutions very carefully by measuring the amounts of distilled water and salt solutions carefully in measuring cylinders, and for even more accuracy I may even use a burette. The variable I am measuring is the strength of the salt solutions. I will have 1 molar of salt solution in a large bowl and use this to make my other strengths by mixing it with distilled water. So I will have 1 molar, which is just 20mls of 1 molar salt solution. Then 0.8 molars, which is 16mls of salt solution and 4mls of distilled water. 0.6M will be 12mls of salt solution and 8mls of distilled water. 0.4M will be 8mls of the salt solution and 12mls of the distilled water. 0.2M will be 4mls o the salt solution and 16mls of the distilled water. 0M will be obviously just 20mls of distilled water. All the solutions will be 20mls. ...read more.

Conclusion

due to the fact that the strongest salt solution has the lowest water potential and therefore more water is diffused from the potato to even out water molecule concentrations. There is a pattern in my results, and it is that my graph clearly shows that the stronger the salt solution that potato was in, the lighter the potato was after 48 hours. There was only 1 anomaly, but it was not very major. It involved the potato cylinder, which was in the 0.2 molar salt solution. After 24 hours this potato cylinder had gained more weight than the potato cylinder in the 0 molar salt solution, which was strange because the 0.2 molar salt solution has the lower water potential than the 0 molar salt solution. However after another 24 hours things were back to normal again as then the potato in the 0.2 molar salt solution had lost more weight that the potato in the 0 molar salt solution, so it worked out okay in the end. In this experiment I predicted exactly what happened in my results, and that was that the stronger the salt solution was, the more weight the potato cylinder would lose. So my prediction was perfectly valid. ...read more.

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