Osmosis Lab Report

Osmosis Abstract Osmosis is essential to many functions of the cell. This process has the ability to create homeostasis when cells are suspended in a hypertonic or hypotonic solution. This experiment was designed to observe how water would attempt to create a balance when synthetic cells, each filled with different molarities of sucrose solutions, were placed in water solutions that were hypotonic to them. Most of the experiment’s results supported the hypothesis, as four out of the five synthetic cells gained weight as a result of water moving into them. Introduction Osmosis is the diffusion of water across a semi-permeable membrane with the intent to balance out two solute concentrations (Brooker 2020). This is a passive process, as solutes are moving from an area of high concentration to low concentration. Sucrose, in this experiment, is considered to be the solute, and the water that it is dissolved in is considered to be the solvent. In this case, the synthetic cells are placed in a solution that is hypotonic to them. Hypotonic refers to a solution that has a lesser solute concentration compared to another solution, like that of the sucrose solution placed in the synthetic cells. Hypertonic refers to a solution that contains more solute concentration, giving the solution a lower water potential (Krayesky et al.). This experiment was designed to witness the process of osmosis in sucrose-filled cells created from dialysis tubing. It was hypothesized that the cells would gain weight after being placed in a hypotonic solution, as the synthetic cells had a higher solute concentration than the water that they were placed in. Materials and Methods flasks. Materials: dialysis tubing, transfer pipettes, beakers, sucrose, water, graduated cylinder, For this experiment, five eight-inch synthetic cells were made out of dialysis tubing, which acted as a semipermeable membrane similar to that of an actual cell. Each synthetic cell consisted of 20 mL of different molarities of sucrose solution. There was a 0.0 M (control group), a 0.2 M, a 0.6 M, a 0.8 M, and a 1.0 M sucrose solution. To make the sucrose solutions that were placed inside the synthetic cells, calculations were made based on the intended molarity (ranging 0.0 M to 1.0 M) and volume (20 mL). These calculations yielded 0.0 grams of sucrose needed for the 0.0 M solution, 1.37 grams of sucrose needed for the 0.2 M solution, 4.10 grams of sucrose needed for the 0.6 M solution, 5.47 grams of sucrose needed for the 0.8 M solution, and, finally, 6.84 grams of sucrose needed for the 1.0 M solution. These amounts of sucrose were individually added to 20 mL of water, creating the ranging molarities of solutions. Once the sucrose solutions were pipetted inside the synthetic cell, the dialysis tubing was tied off. Each synthetic cell was weighed before being placed in beakers of water. The hypothesis was that, with the exception of the control group, water would move into the cell to create homeostasis between the two concentrations, thus, making the cell heavier. The trial cells were each suspended in their own beaker of water for 15 minutes. Upon taking the cells out of the water, they were patted dry and weighed once more. Results are discussed below. Results Initial and final weights of the synthetic cells are recorded in Table 1 below. Percent change in weight, as well as change in weight denoted in grams, are also included in Table 1. Percent change in weight is additionally recorded in Graph 1. Concentration 0.0 M 0.2 M 0.6 M 0.8 M 1.0 M Initial Weight (g) 19.27 g 19.84 g 19.27 g 22.47 g 22.57 g Final Weight (g) 19.01 g 19.91 g 19.92 g 23.94 g 23.68 g Change in Weight (g) -0.26 g 0.07 g 0.65 g 1.47 g 1.11 g % Change in Weight -1.35% .35% 3.37% 6.5% 4.9% Table 1: Summary of initial versus final weights of synthetic cells relative to change in weight Graph 1: Percent change in weight of synthetic cells as their molarities increase Discussion As predicted, the synthetic cells of different molarities of sucrose solution gained weight when placed in water. This excludes the 0.0 M cell, as it actually lost weight when it was predicted to remain at the same weight. This could be due to water escaping when tying the dialysis tubing off. However, it seems that osmosis occurred in the rest of the synthetic cells. This makes sense because when a cell is placed in a solution that is hypotonic to it, water will move into the cell to create homeostasis between the two concentrations.