Abstraction:
Several experiments were performed to detect the colligative belongingss. This includes the freeze point depression. and osmotic force per unit area. Two ice baths were made. one with pure H2O. the other with salt H2O. The lowest temperature was so record for each bath and compared. The salt H2O had a lower freeze point than the pure H2O by 2 grades which supports the hypothesis that solutions have a lower freeze point than pure H2O. The 2nd belongings observed was osmosis force per unit area. This experiment used a 6 inch piece of dialysis tubing that was filled 2/3 full with light Karo sirup and tied off. Then it was wholly submerged in a big glass bowl of room temperature distilled H2O. The dialysis tubing Acts of the Apostless as a semi-permeable barrier and H2O passed through to inside the tubing and over the following several hours. this act caused the tubing to swell. Osmosis is where H2O moves from an country of high concentration to low concentration. hence doing the tubing to swell.
The last experiment involved puting an egg in a jar of acetum. After 24 hours. the shell of the egg wholly disintegrated. Then the jar was rinsed and refilled with Karo sirup where the egg was submerged for 48 hours. This allows osmosis to take topographic point where the H2O inside the egg leaves and moves outside where thereis a lower concentration of H2O. Thus. doing the mass of the egg smaller. This series of experiments takes a closer expression at the colligative belongingss. specifically the freeze point depression and the osmotic force per unit area. Colligative belongingss is where the concentration of solute atoms in a solution is what is of import and non needfully the chemical individuality of the solute.
The first portion of this experiment focuses on the freeze point depression. The freezing point depression is based on the thought that a solution freezes at a lower temperature than the freezing point of pure H2O. Finding the stop deading point of a substance allows the molar mass of a substance to be calculated. The 2nd portion of this experiment observes the colligative belongings of osmotic force per unit area. Osmosis is based on the thought that H2O will travel from an country of high concentration to an country of low concentration. With this information. we can find the individuality of a substance.
Purpose:
Determine the freezing point of H2O
Find the freezing point of a solution
Observe osmotic force per unit area.
Procedures
First. an ice H2O bath was prepared make fulling a 100ml beaker halfway with cool tap H2O and adding a pinch of salt and some crushed ice. Then. the temperature was recorded with a thermometer placed in a trial tubing until a consistent temperature was observed and recorded. Then the trial tubing was placed in the ice bath. Then. the thermometer was stirred inside the trial tubing continuously while the temperature was recorded every 30 seconds until the temperature was consistent once more for 5 back-to-back readings. The same process was repeated a 2nd clip. though this clip with some salt in the trial tubing. Another ice bath was prepared in a 100ml beaker make fulling it midway with distilled H2O and a pinch of salt. An 1/8 teaspoon of iodinated salt with distilled H2O filled up another trial tubing. The initial temperature was recorded until a consistent temperature was observed.
Then. the trial tubing was placed in the ice bath. while the thermometer was stirred inside the trial tubing entering the temperature at 30 2nd intervals until a consistent temperature was observed. Initially. the temperature of the salt H2O mixture did non diminish well so another 1/8 teaspoon of iodinated salt was added. The 2nd belongings we observed was osmotic force per unit area. A 6 inch piece of dialysis tube was placed in room temperature H2O for 30 proceedingss to soak. One terminal of the tube was sealed off by binding the terminal in a knot. Then the tube was filled 2/3 full with light Karo sirup and the other terminal was tied shut go forthing some infinite to spread out.
Then the tube was placed in distilled H2O over a period of several hours and recorded and observed. The last experiment besides observed osmosis. An ordinary big white egg was placed in a quart size Mason jar filled half manner with white acetum and the palpebra screwed shut. Then. it soaked for 24 hours and was rinsed off with distilled H2O. The jar was rinsed out every bit good and refilled half the Mason jar with light Karo sirup. The egg was placed back in the jar with the Karo sirup with the palpebra shutThe egg’s alterations were observed and recorded over several yearss. Temperatures for the Ice Bath experiment:
Answers to Lab Questions
Part 1
B. The freezing point of the pure H2O is -2 grades while the stop deading point of the salt solution is -5 grades. C. The salt solution has a lower freeze point because H2O is the lone thing that freezes. so the salt is left behind. Molecules must come in and go forth the solid stage at the same rate. This occurs at a lower temperature for the solution because of the vapor force per unit area. D. Some practical applications of cognitive belongingss include salting the roads in the winter.
The salt lowers the freezing point of snow/ice. so it takes a lower temperature for roads to stop dead over. Antifreeze in a auto can be used to take down the freezing temperature and besides it can be used to raise the boiling point so autos will non overheat in the summer months. Freeze drying is an illustration of vapor force per unit area take downing. The vapor force per unit area of the environing air is lowered. and it causes the environing air to take heat from the substance which so freezes which preserves perishable stuffs.
Part 2
A. The dialysis bag is comparable to a cell membrane. It allows H2O and little atoms through. while halting big atoms from go throughing through. It is different from a cell membrane because a cell membrane uses many procedures to transport stuffs across the membrane including active conveyance and inactive conveyance. while the dialysis tubing merely uses diffusion. B. The Karo sirup is hypertonic to the egg. Th concentration is higher outside the egg than indoors. so the H2O moves outside of the egg.
C. N=MRT
8. 34 mmHg osmotic force per unit area
23. 6 grades Celcius
0. 5 L of solution incorporating 0. 302 gms of antibiotic
8. 34 mmHg * 1atm/760 mmHG = 0. 01097 standard pressure
0. 01097 atm = M ( 0. 0821 ) ( 23. 6 +273 = 296. 6 K )
M = 0. 01097atm/ ( 0. 0821*296. 6K )
M = 0. 01097atm/24. 35086
M = 4. 505X 10-4 moles of antibiotic
Gram molecules = molar concentration Ten Volume
( 4. 505 Ten 10-4 moles/L ) X ( 0. 5 L ) = 2. 2525 X 10-4 moles
0. 302g/2. 2525 X 10-4 moles = 1340g/mole
Results/Analysis:
The freezing point of the solution was -5 grades. while the stop deading point of the pure H2O was -3 grades. This is a 2 grades difference in the freeze points. This supports the hypothesis that solutions have lower freeze points. The freezing point depression is a colligative belongings used to cipher the molar mass of a substance. However. It was non possible to cipher the molar mass of our substance because with a place lab kit there was no weighing involved. We were still able to enter and find the freezing point of both distilled H2O every bit good as salt H2O. Given more tools to decently put to death the experiment. we would hold come out with more accurate consequence and complete consequences.
For the Karo syrup experiment. after several hours of detecting the Karo sirup in the dialysis tube. The tube swelled up some. nevertheless excessively much Karo sirup was placed in the bag and there was non much room left to swell. The egg was placed in acetum and the shell wholly disappeared after about 24 hours. Then. when placed in Karo sirup for a 48 hours. the egg’s mass appeared smaller. The H2O inside the egg moved out into the environing solution. hence doing the egg’s mass smaller. Decision:
The freeze point depression was observed for pure H2O every bit good as salt H2O. The salt H2O ice bath had a lower freeze point which supports our original hypothesis. Osmotic force per unit area was observed both in the egg experiment and in the dialysis tubing experiment. The egg lost its H2O content and the dialysis tube swelled up. Even though the basic colligative belongingss were demonstrated with these experiments. more accurate consequences would hold been obtained in a more controlled environment. Knowing the weight of the salt would hold been helpful in finding the molecular mass.
