Osmosis Lab

Our bags were filled with 10mL of sucrose at different concentrations; 1%, 10%, and 20%. We had two dialysis bags of a 1% concentration since we will be using it for both beakers in the experiment. A dialysis bag that has a higher concentration of sucrose than the solution would be gaining mass since the water molecules would be passing

In this lab experiment, half our group observed and measured osmosis using dialysis tubes that were represented as the semipermeable membrane. It is permeable to water and other small molecules but is impermeable to larger molecules such as the sucrose solution used in each of the four beakers and tubing. The other half of our group observed the tonicity of sheep blood to determine whether the blood was isotonic, hypotonic, or hypertonic. The 85 g/dL of NaCl solution was the ideal isotonic number in relation to the sheep blood cells as well as a reference to the other observations of the solutions.

Osmosis is a natural occurrence constantly happening within the cells of all living things. For osmosis to occur, water molecules must move across a semipermeable membrane from an area of low concentration to an are of high concentration. In order to understand osmosis, people must understand the different types of concentrations that can be present within solution. One of them is an Isotonic solution where the concentration of dissolved particles is equal to that of a cell’s. Another is a hypertonic solution where there is a higher concentration of dissolved particles then inside the cell. And lastly there is a hypotonic solution where there are less dissolved particles than inside the cell. As dissolved particles move to a region of lower concentration, water moves the opposite direction as a result of there being less water in the highly concentrated region. In this experiment, gummy bears were placed in salt water, sugar water, and tap water to find the measure of osmosis between the solution and gummy bear.

Purpose: The purpose of this lab is to familiarize you with osmosis and, specifically, what happens to cells when they are exposed to solutions of differing tonicities.

7. Explain how incubation plant tissues in a series of dilutions of sucrose can give an

The lab for this paper was conducted for the topic of osmosis, the movement of water from high to low concentration. Five artificial cells were created, each being filled with different concentrated solutions of sucrose. These artificial cells were placed in hypertonic, hypotonic, or isotonic solutions for a period of 90 min. Over time, the rate of osmosis was measured by calculating the weight of each artificial cell on given intervals (every 10 minutes). The resulting weights were recorded and the data was graphed. We then could draw conclusions on the lab.

In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane.

The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.

Osmosis is a process in which molecules in a solvent pass across a semipermeable membrane into a more concentrated solution from a less concentrated one, attempting to make both sides isotonic or equal to each other. Isotonic can also be described as an equilibrium, where there is no net movement of the molecules. Osmosis is relevant in everyday life whether the general population is aware of it or not. It could be as simple as sitting in the pool too long and getting pruney fingers or as complex as a cholera infection in the intestinal cells that does not allow the intestinal cells

Osmosis is defined as the tendency of water to flow through a semipermeable membrane to the side with a lower solute concentration. Water potential can be explained by solutes in a solution. The more positive a number is more likely it will lose water. Therefore should water potential be negative the cell the less likely it will lose water. In using potatoes the effects of the molarity of sucrose on the turgidity of plant cells. According to Clemson University, the average molarity of a White potato is between .24 M and .31 M when submerged in a sorbitol solution. This experiment was conducted with the purpose of explaining the relationship found between the mass in plants when put into varying concentrations of sucrose solutions. Should the potatoes be placed in a solution that contains 0.2M or .4M of sucrose solution it will be hypotonic and gain mass or if placed in .6M< it will be hypertonic and lose mass instead. Controlled Variables in this lab were: Composition of plastic cups, Brand of Russet Potatoes, Brand of Sweet Potatoes and the Temperature of the room. For independent variable that caused the results recorded it was the different Sucrose concentrations (0.0M, 0.2M, 0.4M, 0.6M, 0.8M, 1M). The dependent variable was the percentage change from the initial weighs to the final. The cup with .4 molarity was the closest to an isotonic solution and was used as the control group for the lab. Water potential is the free energy per mole of water. It is

Activity 3: Osmosis Osmosis is a specific type of diffusion. It is the movement of water molecules from an area of high water concentration to an area of low water concentration. Semipermeable membranes, such as the cell membrane, allow the unrestricted movement of water across the membrane, at the same time restricting the movement of solute molecules and ions. It has been estimated that an amount of water roughly equivalent to 250 times the volume of the cell diffuses across the red blood cell membrane every second. Despite this large movement of water molecules, the cell does not lose or gain water, because equal amounts go in and out.

Osmosis is a special type of diffusion where water molecules move down a concentration gradient across a cell membrane. The solute (dissolved substance) concentration affects the rate of osmosis causing it either to speed the process up or slow it down. Based on this, how does different concentrations of sucrose affect the rate of osmosis? If sucrose concentration increases in the selectivity-permeable baggies, then the rate of osmosis will increase.

Cells are always in motion, energy of motion known as kinetic energy. This kinetic energy causes the membranes in motion to bump into each other, causing the membranes to move in another direction – a direction from a higher concentration of the solution to a lower one. Membranes moving around leads to diffusion and osmosis. Diffusion is the random movement of molecules from an area of higher concentration to an area of lower concentration, until they are equally distributed (Mader & Windelspecht, 2012, p. 50). Cells have a plasma membrane that separates the internal cell from the exterior environment. The plasma membrane is selectively permeable which allows certain solvents to pass through

The dialysis bag that contained the greatest net movement of water going in or out of one individual bag turned out to be bag “D”. Bag “D” weighed 11.3 g at the start of the experiment before being placed into the sucrose solution. At the end of the 60-minute time frame, bag “D” weighed 15.7 g. As a result, that means that overall bag D increased therefore making it a gain and letting in more of the sucrose solution that was presented around the bag itself. The hypotheses that were conducted in the beginning both were accepted and rejected. The hypothesis for bag A was rejected because it was hypothesized that there would be a loss of weight but throughout each 15-minute interval, the weight increased from 10.7 g at 0 minutes, to 11.2 by 30 minutes and then decreased to 10.8 g at the 60-minute mark.

We determined that there was no change in the water clarity in the beaker. We determined that the movement of fluids in and out of the dialysis bag was by osmosis and not by diffusion of the sucrose. Our hypothesis as to the net movement of water by osmosis was correct, conversely, our hypothesis as to the chemical movement by diffusion was incorrect. The weight of the dialysis bag increased at each interval, yet there was no change in the color of the water in the beaker suggesting that there was no diffusion. One possible explanation as to the lack of diffusion would be that the sucrose and red dye concentration were not concentrated enough to be observable.