Experiment 2: Water and Water Solutions PDF

EXPERIMENT 2 WATER AND WATER SOLUTIONS THEORY Water is essential in a biological system, comprising almost 95% of a living cell. The human body is 70% water which is mostly found in our blood, brain and lungs. It plays an important role in metabolic processes such as...

EXPERIMENT 2 WATER AND WATER SOLUTIONS THEORY Water is essential in a biological system, comprising almost 95% of a living cell. The human body is 70% water which is mostly found in our blood, brain and lungs. It plays an important role in metabolic processes such as in the digestion of food, transport of waste and regulation of body temperature. Aside from serving as a natural solvent for mineral ions and other substances, it is also a dispersion medium for colloidal cells. Some of the properties of water which are of significance to a living cell are:  Water has a very high surface tension. Surface tension causes the surface portion of water to be attracted to another portion due to cohesion.This allows plants to absorb the diluted minerals from the ground for photosynthesis which will become our own source of minerals and vitamins. This also allows the process of capillarity, which is essential to our breathing.  Water is the Universal solvent. Water can dissolve more substances than any other liquid making it essential for our basic metabolic functions.  Water has the highest latent heat capacity of any common substance. Latent heat capacity is determined by the amount of extra energy you have to put into a liquid to change its state from solid - liquid - gas. This property makes it an effective coolant for the human body via evaporation of perspiration, extending the range of temperatures in which humans can exist  Water is the primary energizer of all functions in the body. It manufactures hydroelectric energy at the cell membranes all over the body, particularly in the neurotransmitter system. Through its hydrolytic properties, it helps in the digestion of foods into its absorbable form.  Water is also the adhesive that bonds cell membranes. Therefore, it plays an all-encompassing role in energy metabolism and the physiologic functions of the body. OBJECTIVE To demonstrate physiological processes that water solutions may undergo. 5 MATERIALS cellophane bag digital balance rubber band pipette 4 250 ml beakers dropper 2 test tubes stirring rod Bunsen burner test tube rack test tube holder aspirator test tube brush REAGENTS Vinegar Benedicts reagent distilled water 1% starch solution syrup iodine solution 15% glucose solution 2 eggs PROCEDURE 1. Osmosis Weigh the two eggs separately and record their masses. Place the eggs in a beaker of vinegar until the calcium shell dissolve and the cell membrane become expose. Weigh the eggs and record their masses. Then place them in a beaker of syrup until a change in the texture of the cell membrane can be noted. Weigh and record their masses. Finally place the eggs in a beaker of distilled water. After half an hour observe the appearance of its cell membrane. Weigh the eggs and record their masses. Take note of all observations. 2. Dialysis Mix 15 ml of 15% glucose solution and 15 ml of 1% starch solution in a beaker. Place the mixture in a cellophane bag and suspend the cellophane bag in a stirring rod by means of a rubber band. Immerse the cellophane bag containing the mixture into a beaker of water as shown in the figure. After 30 minutes, take 5 ml of the water in the beaker and place in a test tube. Add a drop of iodine solution and observe the color produced. 6  Into another test tube place 5 ml of Benedict’s reagent and add into it 10 drops of the water from the beaker. Boil for 2 minutes over a low flame and allow to cool. Observe the color formed. Figure (set – up for dialysis) rubber band stirring rod H2 O glucose and cellophane starch H2O solution H2O 7 Name ______________________________ Rating _________ Course/Year & Section ________________ Date __________ EXPERIMENT 2 WATER AND WATER SOLUTIONS REPORT / ANSWER SHEET DATA AND RESULTS Results of Osmosis for egg 1 Solutions Egg mass Observations Egg mass Observations before (in before placed after (in after removed grams) in solution grams) from solution Vinegar Syrup Water Results of Osmosis for egg 2 Solutions Egg mass Observations Egg mass Observations before (in before placed after (in after removed grams) in solution grams) from solution Vinegar 8  Syrup Water Results of Dialysis Test Reagent Color Result Iodine Reagent Benedict’s Reagent QUESTIONS 1. What is the difference between osmosis and dialysis? 2. Upon placing the eggs in a beaker of syrup, in what direction did the water molecules move? What kind of solution is syrup? 3. When the eggs were placed in a beaker of distilled water, in what direction did water molecules move? On what evidence do you base your answer? 4. Which molecule passes out of the cellophane bag, the starch molecule or the glucose molecule? Which test proved your answer? 9 GENERALIZATION 10