Potato Osmosis Lab

In this experiment, we worked with potatoes, also known as solanum tuberosum (Watkins, n.d). Potatoes are starchy crops that provide a lot of energy. For this experiment, our hypothesis was: If the pH level of the solution is more basic, then the potato membrane will weigh less due to osmosis. Our null hypothesis was: If the pH level of a solution is either acidic or basic, then it will have no effect on the weight. The independent variable was the different solutions of different pH values. The dependent variable was the weight of the potato, which was measured in grams. The baseline of this experiment is the weight of the potato when in the milk solution because milk has a neutral pH. The controls in this experiment are that each sample had
Osmosis is defined as: “the diffusion of free water across a selectively permeable membrane” (Reese et all., 2014). Selectively permeable membranes only allow certain substances to pass through them. They allow things such as oxygen, water, carbon dioxide, and lipids to pass through. On the other hand, selectively permeable membranes do not let ions or larger polar molecules such as sucrose and proteins to pass through (Diffen.com, 2015). In order to get ions and large molecules to pass through, they need help by channel proteins and carrier proteins. Osmosis is a type of passive transport, which means that it requires no expenditure of energy. It also requires water for movement. It wouldn’t be able to function without it. An example of osmosis is a sponge and how water moves through it from an area of low concentration to an area of high concentration. Osmosis was discovered by René Joachim Henri Dutrochet in 1826. Dutrochet’s research on osmosis and diffusion attracted a lot of attention to the public. He observed “that certain organic membranes allow the passage of water but stop the molecules dissolved in it” (Encyclopedia.com, 2008). He noticed that between two solutions of different concentrations in a membrane, water passes from an area of low concentration to an area of higher concentration (Encyclopedia.com). Even though Dutrochet’s experiments were fairly simple and not very accurate, he made the first steps toward the study
We tested the weights of the potato membranes every 5 minutes in the different solutions of pH. PH is defined as “a measure of hydrogen ion concentration equal to –log[H+]” (Reese et al., 2014). It measures how acidic or alkaline (basic) something is. It ranges from 0 to 14, with 7 being neutral. Acids are solutions that have a higher concentration of hydrogen ions and less hydroxide ions. Bases are solutions that have a higher concentration of hydroxide ions and a less concentration of hydrogen ions (Reese et al., 2014). Because the pH scale is logarithmic, each pH value below 7 is 10 times more acidic than the next one (Helmenstine, n.d.). This goes vice versa with pH levels above seven, being 10 times more alkaline. Lemon juice, black coffee, milk, milk of magnesium, and bleach were the solutions used in this experiment. Their pH’s were 2, 5, 7, 10, and 12. The term “pH” was first described by a biochemist named Søren Peter Lauritz Sørensen in 1909. It stands for “power of hydrogen”. The p is short for the German word meaning power, potenz. The H stands for the element hydrogen. The H is capitalized in pH because it is a standard in science to capitalize the element symbols (Helmenstine, n.d.). Limus paper is the type of paper that we use to measure the acidity of a