Write background,purpose, and procedure on colligative properties and osmosis pressure. (Procedure I)To begin this experiment,you will make a water bath. Half-fill the 100-ml beaker with cool tap water. Place the crushed ice in the beaker so that the water is just below the top of the beaker. The water level should not be higher than the length of the test tube. Then sprinkle a little salt into the ice water, mix well. Then you will half fill the test tube with distilled water.Set the tube into the well plate. Insert the thermometer into the test tube and take readings every 30 seconds until the readings remain constant, then record the temperature of the distilled water.You will then place the test tube in the beakers ice water bath and set your stopwatch at zero. Carefully stir the water in the test tube with the “thermometer and record the temperature of the water at 30 second intervals. You should see the temperature of the water rapidly decrease from -1 degrees celcius to -3 degree celcius adn then rise to 0 degree celcius. At that time the readings should remain constant before again decreasing. This is supercooling.Once five consectutive readings have been made at a constant temperature, remove the test tube from the bath and empty it into a sink. Then refill half of the test tube with room temperature distilled water (at least 10 degree celcius) and add 1/8 teaspoon of salt to the distilled water in the test tube. Mix well until dissolved. Either prepare a fresh water bath or add more ice and a little salt to the existing water bath. Repeat steps 2-5 using the saltwater solutioin prepared in step 7 above. You may not observe supercooling this time. Pour the water from the test tube and from the water bath down the drain. Clean up your equipment and replace it in the labpac. Make two graphs of your data. On one graph plot the data from the pure water. On the other graph plot the data from the salt solution. On both plot temperature on the y-axis and time on the x-axis. Once observed two fairly linear regions on each graph. Draw the best straight lines for these regions. You should have two straight lines on each graph. On each graph extend these lines until they intersect. The points of intersection are the points you will record as your freezing points. Then (Procedure II) (Sugar solution) Half-fill a glass bowl with distilled water Place the dialysis tubing in it. Make sure the tubing is completely submerged and let it soak for 20-30 minutes.Gather your funnel, two rubber bands,and your Karo syrup and proceed to (PART THREE )(“Raw Egg” Procedure) While the tubing is soaking. After the tubing has soaked 20-30 minutes remove it from the water and put it on a paper towel. Pour the water down the drain and rinse the bowl with distilled water. Then refill the bowl halfway with distilled water. Carefully close off one end of the dialysis tubing using a rubber band. You may want to cut the rubber band and tie off the tubing or you may just want to wrap the rubber band around the tubing serveral times. Regardless, make certain the closure is as tight as possible to avoid leaks. Use the funnel to carefully fill the dialysis tubing 1/3 -full with karo syrup. Do not get any karo on the outside of the tubing. Close off the other end of the tubing as in step 5. Put the Karo filled tubing into the distilled water in the glass bowl. Make sure the tubing is completely submerged. Observe the tubing several times over the next serveral hours. Record your results. At last clean up by pouring the liquids down your drain, washing and rinsing bowl, and throwing the used dialysis tubing into the garbage. Raw Egg: To perform thsi experiment you will check your raw egg to make sure the shell is not cracked. Use only an egg with an intact shell or it will not work. Gently place the egg into the pint jar. Record your observations of the egg. Then pour vinegar over the egg to cover it completely, put the top on the jar , set it aside for 12 to 24 hours to allow the vinegar to completely dissolve the shell of the egg. During this period observe the egg several times record your observations. After the shell has dissolved, record your observations of the egg. Carefully, remove the egg from the Karo syrup gently rinse it under tap water, and record your observations. Dispose of the egg by throwing it in the trash. And clean the equipment you used.
Questions:
DATA TABLE 1: PURE WATER AND SALT SOLUTION
seconds:0,30,60,90,120,150,180,210,240,270,300,330,360,390,420,450,480,510,540,570,600,630,660
H2O Temperature for each seconds
H2O Ice Bath for each seconds
Salt Water Temp for each seconds
Salt water Ice bath for each seconds
B. Record the freezing point of the pure water and the freezing point of salt solution.
C. How do these two freezing points compare?
D.What are some practical applications of freezing point depression, boiling point elevation,and vapor pressure lowering?
A.To what biological structure is the dialysis bag comparable? How is it similar? How is it different?
B. In your experiment is the Karo hypotonic or hypertonic to the egg?
c.Historically certain colligative properties – freezing point depression, boiling point depression, and osmotic pressure- have been used to determine molecular mass. (Now there are instrumental methods to determine this) Of these three, osmotic pressure is the most sensitive and gives the best results, Molecular mass can be found according the following equation:
Osmotic pressure,Molarity of solution, The ideal gas constant (0.0821 L x atm/mol XK), and, T= Kelvin Temperature
Problem for lab report: At 23.6 degree celcius ,0.5
00L of a solution containing 0.302 grams of an antibiotic has an osmotic pressure of 8.34 mm Hg. What is its molecular mass?
Conclusion: Write a conclusion to summarize the lab report.
DO NOT WORRY ABOUT DOING THE LAB I WILL DO THE LAB MYSELF. BUT DO INCLUDE GRAPH ANSWER QUESTIONS AND THAT SORT OF THING. THANKS
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