Colligative Properties

8. What type of membrane does the dialysis tubing represent? Give an example of this type of

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.

This is also known as a hypertonic solution which explains why the egg will decrease in size. Corn syrup is a hypertonic liquid because it is very concentrated with not much water compared to the egg unlike water which is hypotonic because it contains more water than the egg. In this solution, the solute remains the egg, and the solvent is changed to corn syrup. Osmosis still plays an action because water is still passing through the membrane from high to low concentrations.

Osmosis is described in one of three ways when comparing more than one solution. The cell’s external and internal environment helps determine tonicity, which is defined as how the cell reacts to its environment. When the cell’s environment is equal in osmolarity to itself and there is no change, it is considered an isotonic solution. When the environment has a higher osmolarity, shrinkage occurs and it is considered a hypertonic solution. When the environment has a lower osmolarity, swellings occurs and it is considered hypotonic.

Other substances that dissolve in water also lower the freezing point of the solution. The amount by which the freezing point is lowered depends only on the number of molecules dissolved, not on their chemical nature. This is an example of a colligative property. In this project, you'll investigate different substances to see how they affect the rate at which ice cubes melt. You'll test substances that dissolve in water (i.e., soluble substances), like salt and sugar, as well as substances that don't dissolve in water (i.e., insoluble substances), like sand and pepper. Which substances will speed up the melting of the ice?

Dry ice is a solid form of carbon dioxide that produces a cold dense mist. I first learned what Dry Ice was in fifth grade, this was due to the fact that my class had taken a field trip to River Legacy Park. Where we saw an experiment and learned facts about dry ice. This led to a fascination with dry ice, in this experiment I will test whether the temperature of water and soda affect when poured over Dry ice. Dry Ice has multiple purposes some of which, is chemotherapy, to carbonate liquids, store food, and accelerate plant growth. Since, I always liked the thought of working with Dry Ice I had begun to think of an experiment to do for the IA involving Dry Ice. After much consideration I choose to test how soda and water would

Dialysis tubing is a membrane made of regenerated cellulose fibers formed into a flat tube. If two solutions containing dissolved substances of different molecular weights are separated by this membrane, some substances may readily pass through the pores of the membrane, but others may be excluded.

Through our data acquisition on day one our predicted values for the change in temperature of our NaCl solution in water was slightly off. This was most likely due to recording the freezing temperature sometime after the precise moment of the solution freezing. However, we predicted that as we doubled our concentration of NaCl in solution the freezing point depression would also double which is consistent with our results. Through our day one experiments we were able to better understand the ability of NaCl as a deicer by understanding how the freezing point depression changes based on concentration. We could further test these results by testing with different concentrations of NaCl.

Table 1 shows the contents of the bags and the content of the concentration it was submersed in. Bags 2-4 each contain a solution of both sucrose and water. These bags were each put into beakers containing hypertonic solution. These bags gained weight over time because the water moved from its high concentration inside the beaker to the low concentration inside the membrane of the artificial cell, the membrane being the bags that consisted of dialysis tubing. The

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.

In this study we constructed we researched whether different sucrose concentrations affect the rate of osmosis. In order to do this, we constructed artificial cells out of dialysis tubing filled with 20% sucrose and 40% sucrose and weighed them every 10 minutes for 90 minutes. In doing so, we concluded that the higher the sucrose concentration, the faster the rate of osmosis.

In the third stage of this experiment, the density of a liquid was determined and compared to known standards. A 100ml beaker was filled to about half-full with room-temperature distilled water. The temperature of the water in ◦C was recorded in order to compare to known standards later. A 50ml beaker was then weighed on a scale in order to determine mass and recorded. A sample of the distilled water with an exact volume of 10ml was then placed in the 50ml beaker using a volumetric pipette. The 50ml beaker with the 10ml of water was then weighed again and the initial mass of the beaker was subtracted from this mass to obtain the mass of the 10ml of water. With the volume and the mass of the water now known, density was calculated using d = m/V and recorded in g/ml. This process was then repeated to check for precision and compared to standard values to check for accuracy. Standard values were obtained from CRC Handbook, 88th Ed.

One dialysis tube was submerged in each beaker. Osmosis was allowed to occur for 5 minutes and then all of the tubes were removed from the water. The tubes were dried off and measured on the triple beam scale. The mass was taken and recorded for all three tubes. I then placed the tubes back into their respective solutions. The process was repeated four times for each tube in 5 minute increments, and then the materials were disposed of. The rate of diffusion of water in each solution was

Secondly, osmosis was to be observed to gain a proper understanding of how the principal of dialysis functions.