Methodical Instruction for Students of the 1 Course Medical Faculty
LESSON № 1 (PRACTICAL – 6 HOURS)
Themes: 1: Introduction. Concentration units (3 hours).
2. Colligative properties of solutions (seminar) (3 hours).
Aim: To be able to learn main rules of safety precautions in chemical laboratory and concentration units and colligative properties of solutions
Professional orientation of students:
The knowledge main rules of safety precautions are important for you working in chemical laboratory. The amounts of mattes (concentration) are main character of solutions. Concentration unit is used for preparation solution in the biochemistry, the hygiene, the therapeutic and the surgical clinics.
The phenomenon of osmosis is very important for vegetative and animal cells. It influences for exchange of water between a cells and intercellular medium of living organisms. Peculiarly resilient and elastic tissue and saved the definite form of organs by the osmotic pressure. Amount of water is enough for physical and chemical processes in an organism (a hydration, dissociation, hydrolysis, saponification, et al), which is in cells and tissues.
Methodology of Practical Class (900-1200).
I. Introduction. Concentration units.
I. Introduction. Concentration units.
Work 1. To prepare the 0.01 (1%) of sodium chlorite solution.
Materials: crystalline of NaCl, distilled water, volumetric flack.
Protocol: to prepare 200g (or
1. To calculate the amount of a salt and water, this is necessary for preparation of solution.
2. To measure of sodium chloride by technical balance.
3. To add a weighted salt in a beaker or flask.
4. To measure by graduated cylinder of distilled water and pour into a glass flask with a salt.
5. To mix the contents of the flasks by glass rod until complete dissolution of the salt.
Work 2. To prepare the physiological solution of sodium chlorite
Physiological solution it is sodium chlorate solution with mass fraction equally 0,89 %.
Materials: 10 % NaCl solution with density
Protocol. to prepare 200 mls (or 150 mls, or 100 mls, or 250 mls) the 0.0089 (0.89 %) of sodium chlorite solution
In measuring flack add some volume (which necessary is calculated) solution with mass fraction 10 % and density
Calculation: If density and volume (you ask the teacher) of a physiological solution is known, so you can calculate quantity NaCl, which necessary for making this volume of physiological solution by the formula:
After that you calculate mass solution with mass fraction 10 %, in which there are same mass salt of NaCl as in physiological solution by the formula:
Knowing density of this solution we shall be calculate its volume:
Work 3. To prepare the solution with known molaryty.
Materials: crystalline of NaCl, distilled water, volumetric flack.
Protocol. to prepare 200 mls (or 150 mls, or 100 mls, or 250 mls) the sodium chlorite solution with the molaryty of sodium chloride 0.1 mol / l (
1. To calculate the amount of a salt, this is necessary for preparation of solution by formula:
CM – molaryty;
ν – number mole of sodium chloride;
V- volume of solution.
2. To measure amount of sodium chloride by technical balance.
3. To add a weighted salt in a volumetric flask.
4. To add distilled water into the flask with a salt.
5. To mix until the salt dissolve.
Individual Students Program.
I. Introduction. Concentration units.
1. Water. Solubility compounds in water. Solution.
2. Concentration units.
3. Mass fraction (percentage by weight).
4. Mole. Molar fraction.
5. Volume fraction.
6. Mass concentration (titer).
7. The molar concentration (molarity).
8. Molar concentration (molality).
9. Normal concentration (normality).
II. Colligative properties of solutions. (seminar)
1. Solubility. The mechanism of dissolving.
2. Solubility of gases in liquids. The Henry’s law. Solubility of solids and liquids in liquids. Critical temperature of solubility liquids in liquids.
3. Colligative properties
4. Essence of an osmosis phenomenon. The vant’-Hoff’s law. Hemolysis and plasmolysis.
5. Vapor-pressure lowering of solution. A Raoult’s law.
6. Boiling-point elevation and freezing of solutions. An isotonic coefficient.
Seminar discussion of theoretical issues (1230 – 1400 hour).
Test evaluation and situational tasks.
1. If
2. If 4.50 g of ammonia, NH3, is dissolved in 3.30×102 g of water, what is the mole fraction of ammonia in the resulting solution?
3. If 4.50 g of ammonia, NH3, is dissolved in 3.30.102 g of water, what is the mol % NH3 in the resulting solution?
4. 28.6 g of sucrose (cane sugar, C12H22O11) is dissolved in 101.4 g of water. What is the percent by mass of the sucrose in the solution?
5. 4.50 g of ammonia is dissolved in 3.30 X 102 g of water. What is the percent NH3 by mass?
6. How much NaCl solution with mass faction of 10 % and density 1,05 g / сm3 is necessary for making 200 mls of a physiological solution (0,89 %)?
7. What volume should be taken solution HCl with mass fraction 4 % and density 1,018 g / m3 for making 250 mls 0,12 mol/l of solution?
8. 10.0 g of ascorbic acid (vitamin C, H2C2H6O6) is dissolved in enough water to prepare 125 ml of solution. What is the molar concentration (molarity) of this compound in the solution?
9. 3.30 g of ethanol, C2H5OH, is dissolved in enough water to make the total volume 0.150 l. What is the molarity of the ethanol?
10. 10.6 g of ammonium chloride is dissolved in 152.4 g of water. If the density of the solution is 1.02 g× ml-1, what is the molar concentration of NH4Cl?
11. 28.6 g of sucrose (cane sugar, C12H22O11) is dissolved in 101.4 g of water. What is the molality of the sucrose in the solution?
12. 250 mls solution contains the
13. 0,05 mole of non-electrolyte is in one liter of solution. What is osmotic pressure of this solution at 37 оС?
14. 100 mls solution is contained a 1 g sugar С12Н22О11. Osmotic pressure of this solution is 0,655 atm. at 0 оС. To calculate the value of constant R in the vant-Hoff’s equalization РV = nRT.
15. Haw many moles of non-electrolytes is contained in one liter of solution, if osmotic pressure has been 2 atm at 17оС made.
16. Solution, which contains 3,75 g methanal in a liter, has osmotic pressure 2,5 atm at 0 оС. To calculate molar mass of methanal.
17. 3 g sucrose С12Н22О11 is in a 250 mls solution. What is temperature in system, if osmotic pressure is 0,82 atm?
18. 0,2 mole of sugar is dissolved in 450 mls of water at 20 оС. What is vapor pressure of this solution, if vapor pressure of water is 17,6 mm Hg at the same temperature?
19. What is vapor pressure of 10% glucose (С6Н12О6) solution of at 100 оС?
20. What is vapor-pressure lowering of solution, which contain a 36 g glucose in 540 g water, if vapor pressure of water is 61,5 mm Hg at the same temperature?
21. Vapor pressure water is 233,8 mm Hg. Vapor pressure solution, which contain a 12 g matters in 270 g of water is 230,68 mm Hg at the same temperature. To calculate molar mass of the solute.
22. 0,94 g of some compound is dissolved at a 50 g ethanol. The boiling-point elevation of this solution is 0,232 оС. To calculate molar mass solute (Е (ethanol) = 1,16оС).
23. What is freezing temperature of solution, if 54 g glucose (С6Н12О6) is dissolved in 250 mls water? (К(water) = 1,86 оС).
24. What is boiling-point elevation of this solution, if 9 g glucose is dissolved in 100 g of water (Е (water) = 0,52 оС)?
25. How much grams of the sugar (С6Н12О6) are needed dissolved in 100 g water, if to boiling-point elevation of this solution is 1 оС (Е (water) = 0,52 оС)?
26. How much grams of the glucose С6Н12О6 are needed to dissolved in 100 g water, if freezing-point depression of this solution is 3 оС ? (К(water). = 1,86 оС).
27. The 8,9 g anthracene С14Н10 is dissolved in a 200 g of ethanol. The boiling-point elevation of this solution is 0,29 оС. To calculate boiling-point elevation constant of the ethanol.
28. What concentration of glucose solution will be isosmotic wilth blood plasma having an osmolarity of 0.3 osm, i.е. 300 mosm/L?
29. What concentration of NaCl solution will be 0.3 osm/l (= 300 mosm/l)?
Correct answers of test evaluations and situational tasks:
1. The molecular mass of C12H22O11 is 342.3, and so
The molecular mass of H2O is 18.02, and so
Therefore,
mol % sucrose = Xsucrose ×100 = 1.46×10-2×100 = 1.46% (The solution is 1.46 mol % sucrose and 98.54 mol % water.)
2. 1.42 ×10-2.
3. 1.42 mol %.
4.
5. 1.35 %.
6. If density of a physiological solution is one gram in liter, so possible to calculate quantity NaCl, which necessary for making of
Unfortunate, we have solution of NaCl with mass fraction 0,1 (10 %), but have not salt of sodium chlorate, so we shall be calculate mass of solution in which there are
Knowing density of this solution we shall be calculate its volume:
7. The first of all we calculate normal concentration 4 % solution of HCІ by the formula:
After that we calculate a volume its solution:
8. The molecular mass of H2C2H6O6 is 176.1. Therefore,
The volume of the solution is 125 ml, or
9.
10.
11. The number of moles of sucrose is n=
12. M =179.
13. 128,867 kPa.
14. 0.082.
15. 0.084 moles.
16. 30 g/mole.
17. 285 K.
18. 17.46 mm Hg.
19. 751.65 mm Hg.
20. 61.09 mm Hg.
21. 61 g/mole.
22. 94 g/mole.
23. –2.232 оС.
24. 0.26 оС.
25. 34.6 g.
26. 29 g.
27. 1.16 оС.
28. One osm/l solution of glucose = 1 molar (М) solution of glucose = 180 grams glucose/L 300 mosm/L (0.3 osm/L) solution of glucose = 0.3 М solution of glucose which is prepared by dissolving 180 х 0.3 = 54 grams of glucose in sufficient water to make final volume equal to one liter. (Note: 180=mol.wt. of glucose). Thus 5.4 % solution of glucose will be isosmotic with blood plasma. In clinical practice 5 % glucose in water is infused intravenously to replenish plasma volume in patients of hypovolemia.
29. As NaCl will dissociate into Na+ and Cl– ions, therefore its 0.15 М solution will possess osmolarity of 0.3 mol/1. 0.15 М solution of NaCl is prepared by dissolving 58.5 х 0.15 = 8.775 grams of NaCl in sufficient water to make а final volume of one liter. (Note: 58.5 is the mol. wt. of NaC1). In clinical practice 0.9 NaCl is used as isotonic fluid for intravenous infusion.
Individual student work (1415-1500 hour) are checked by solving situational tasks for each topic, answers in test evaluations and constructive questions (the instructor has tests & situational tasks).
Students must know:
– concentration units;
– to calculate concentration of solutions by different ways;
– Colligative properties of solutions: osmosis, vapor-pressure lowering of solution, boiling-point elevation, freezing-point depression, osmotic pressure;
– dissolubility of gases, solid matters and liquids in liquids;
– essence of phenomenon hemolisis, plasmolisis;
– the Henry law, the law of Van’t-Hoff, the Raoult law.
Students should be able to:
– to make a solutions, if is knowing the concentration;
– to calculate concentration by the formula and well-known mass of solute.
References.
Basic:
1. Atkins P.W. Physical chemistry. –
2. http://intranet.tdmu.edu.ua/Student’s facilities/Practical classes materials/Department of General Chemistry/medical chemistry/medical/1 course/English/01. Solutions. Concentration. Colligative propeties of solutions
3. Robert R Crichton; Frédéric Lallemand; Ioanna S M Psalti; Roberta J Ward. Biological inorganic chemistry: an introduction.
Additional:
1. Lawrence D. Didona. Analytical chemistry. – 2002:
2. John B.Russell. General chemistry. New York.2002. – P. 382-386
The methodical instruction has been worked out by: Associate Prof. Dmukhulska Ye. B.
Methodical instruction was discussed and adopted at the Department sitting
25.06.2013. Minutes N 11
Methodical instruction was adopted and reviewed at the Department sitting
27.08.2013. Minutes N 1
