Physical Pharmacy Lab Manual PDF

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DEPARTMENT:

Pharmaceutics

COURSE:

BPharm II

Physical Pharmacy Practical Manual

UNAM, School of Pharmacy - Pharmaceutics

Practical Index

1. Solubility and Disintegration:

2. Intermolecular Forces and Solution Properties: 

A: To investigate evaporation and to determine the relation between evaporation and intermolecular forces.

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B: To investigate solubility and to determine the relation between solubility and intermolecular forces.

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C: To investigate boiling point and to determine the relation between boiling point and intermolecular forces.

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D: To investigate capillarity and to determine the relation between capillarity and intermolecular forces.

3. Chemical Equilibrium and Le Chatelier’s Principle 4. States of Matter 5. Buffer and Isotonic Solutions 6. Partition Phenomenon 7. Ionic Properties 8. Protein Binding and Complexation 9. Stability and Kinetic Reaction Studies

UNAM, School of Pharmacy - Pharmaceutics

LAB SAFETY In the laboratory, students should behave in accordance with the following general rules that are also displayed on the walls in the laboratories:

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The practical classes begin promptly at the prescribed times. No student is allowed in the laboratory before or after these times.

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Take note of the “prohibited” signs in the laboratory.

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Components that had been distributed must be handed in at the end of the practical.

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Connecting wire must also be returned.

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All electrical instruments must be switched off at the end of the practical.

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Chairs must be returned to their places after use.

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Tidy bench after use.

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Defective equipment must be entered in designated fault book in the laboratory.

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Pregnant students have to get special permission to enter any laboratory.

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Students, who do not heed the above rules, could be prohibited from using the laboratory again.

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Please do not carry apparatus from one table to the other without permission of the demonstrator. No electrical circuit is to be switched on before it is checked by a demonstrator. Switch everything off after you have finished using it.

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Please be careful with gas and Bunsen burners. Make sure they are switched off after usage.

UNAM, School of Pharmacy - Pharmaceutics

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Please leave the apparatus in neat order after completion of your experiment. Switch off all electrical equipment and disconnect the leads.

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Report any problems with apparatus (apparatus out of order, etc) without delay to a demonstrator.

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Handle all apparatus with respect.

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Please do not smoke in the laboratory and keep noise levels down.

UNAM, School of Pharmacy - Pharmaceutics

1. Solubility and Disintegration  The dissolution of the same tablet in different solvents at different temperatures: Solvents:

Water NaCl NaOH

Materials:

Procedure:

2x tablets per Solvent (=6 tablets per group) 1. Dissolve a tablet at RT in each solvent Three solvents in test tubes

2. Record time and behaviour of dissolution

Heater

-Repeat (1-2) in a water bath at 37C Take pictures of tablet dissolution process 

Water bath Thermometer Stop-watch SOLVENT (T) to dissolve at: a) Room temperature Behaviour of tablet at RT b) 37C (using a water bath for NaCl and NaOH) Behaviour of tablet at 37C

Water

NaCl solution

UNAM, School of Pharmacy - Pharmaceutics

NaOH solution

2. Intermolecular forces and Properties of Solutions The following five experiments investigate the effect of various physical properties (evaporation, surface tension, solubility, boiling point and capillarity) of substances and determine how these properties relate to intermolecular forces. Each experiment will look at a different property. A: The effects of intermolecular forces: Aim To investigate evaporation and to determine the relation between evaporation and intermolecular forces. Apparatus You will need the following items for this experiment:  

ethanol, water, nail polish remover (acetone), isopropanol evaporating dishes (or shallow basins) or measuring cylinders

Method 1. Place 10 ml of each substance given in separate evaporating dishes. 2. Carefully move each dish to a warm (sunny) spot. 3. Mark the level of liquid in each dish using a permanent marker. Make several marks at different positions around the dish. If the permanent marker is leaving a smudge rather than a noticeable mark, carefully wipe the side of the dish and try again. 4. Observe each dish every 10 minutes and note which liquid evaporates fastest. Results Record your results in the table below. You do not need to measure the level of the liquid, but rather just write how much the level had dropped (e.g. for water you might write did not notice any decrease in the level or for ethanol you might write almost all the liquid had evaporated). Substance

Liquid level after 10 min

20 min

30 min

Ethanol Water Nail polish remover Isopropanol Discussion and conclusion Which solvent takes the longest to evaporate? ______________________________________ Which solvent evaporates the fastest? ____________________________________________

UNAM, School of Pharmacy - Pharmaceutics

60 min

Explain why in terms of intermolecular forces: _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _____________________________________________ Circle the correct answer: Substances with weaker intermolecular forces evaporate faster/slower than substances with stronger intermolecular forces. (5)

B: The effects of intermolecular forces: Aim To investigate solubility and to determine the relation between solubility and intermolecular forces. Apparatus You will need the following items for this experiment:     

Solids: sodium chloride (table salt), iodine, potassium permanganate Solvents: water, ethanol, chloroform 9 beakers or test-tubes or vials Pipettes 3 A4 sheets of paper Method

1. Place about 10 ml of each solvent given in separate beakers. Place this set on a piece of paper labelled “sodium chloride”. 2. Repeat this step twice. The second set is for potassium permanganate (so your piece of paper will say “potassium permanganate”) and the third set is for iodine (so your piece of paper will say “iodine”). You should now have nine beakers in total. 3. Into the first set, add about 1 g of sodium chloride. 4. Into the second set, add about 1 g of potassium permanganate. 5. Into the third set, add about 1 g of iodine. 6. Observe how much of each substance dissolves in the solvent.

UNAM, School of Pharmacy - Pharmaceutics

Results Record your results in the table below. If you observe only a small amount of the solid dissolving then write that very little solid dissolved. If all the solid dissolves then write that all the solid dissolved. Substance

Water

Chloroform

Ethanol

Sodium chloride Potassium permanganate Iodine Discussion and conclusion Which substances dissolved in the solvents? _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ Which of the substances did not dissolve? _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ Explain why in terms of polarity and intermolecular forces. _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ ___________________________________________________________________________________________________________(5)

UNAM, School of Pharmacy - Pharmaceutics

C: The effects of intermolecular forces: Aim To investigate boiling point and to determine the relation between boiling point and intermolecular forces. Apparatus You will need the following items for this experiment: water, cooking oil (sunflower oil), nail polish remover, isopropanol test-tubes and a beaker hot plate Stopwatch

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Method Warning: Nail polish remover is highly flammable. It will easily catch fire if left near an open flame. For this reason it must be heated in a water/oil bath. This experiment MUST be performed in a well ventilated room. 1. 2. 3. 4.

Place about 10 ml of each substance given in separate test-tubes. Half-fill the beaker with water and place on the hot plate. Place the test-tubes in the beaker. Observe how long each substance takes to boil. As soon as a substance boils, remove it from the water bath.

Results Write down the order in which the substances boiled, starting with the substance that boiled first and ending with the substance that boiled last. Order of boiling point 1 2 3 4

Substance

Discussion and conclusion Which two substances boil first? _______________________________________________________________________________________________________________ ____________________________________________________________________________________________________________

UNAM, School of Pharmacy - Pharmaceutics

Explain why these substances boil before the others: _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ Which substance between water and oil, would boil first? ___________________________________________________________________________ Explain why in terms of intermolecular forces: _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ Circle the correct answer: Substances with strong intermolecular forces will have a higher/lower boiling point than substances with weaker intermolecular forces. (5) D: The effects of intermolecular forces: Aim To investigate capillarity (how far up a tube a liquid rises or how far down a liquid falls) and to determine the relation between capillarity and intermolecular forces. Apparatus You will need the following items for this experiment:  

water, cooking oil (sunflower oil), nail polish remover, isopropanol large shallow dish, narrow glass tube

Method 1. 2. 3. 4.

Place about 20 ml of water in the shallow dish. Hold the narrow tube just above the level of the water in the dish. Observe how far up the tube the water travels. Repeat for the other three substances, remembering to wash and dry the dish and tube well between each one.

UNAM, School of Pharmacy - Pharmaceutics

Results Record your results in the table below. You do not need to measure how far up the tube the substance travels but rather say if it only travelled a short distance or a long distance. Substance

Distance travelled up tube

Water Oil Nail polish remover Isopropanol

Discussion and conclusion Which substance travels the furthest? ____________________________________________ Which substance travels the least distance? ________________________________________

Complete the sentence: These results are observed because capillarity is related to ____________________________ Circle the correct answers: Substances with strong/weak intermolecular forces will travel further up a narrow tube (have a greater capillarity) than substances with stronger/weaker intermolecular forces. (5) Overall Conclusion Write a summary of the effects of intermolecular forces on surface tension, solubility, evaporation, boiling point and capillarity. _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ UNAM, School of Pharmacy - Pharmaceutics

_______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ _______________________________________________________________________________________________________________ __________________________________________________________________________________________________________(5)

UNAM, School of Pharmacy - Pharmaceutics

3. Equilibrium/ Le Chatelier’s Principle Traditionally, equilibrium experiments and Le Chatelier’s Principle are illustrated using the following experiments: exo 2(A) CoCl4 + 6H2O Co(H2O)62+ + 4Clblue endo red This experiment is used to demonstrate the effects of both temperature changes and concentration changes on an equilibrium mixture. (B) Cr2O72- + H2O orange

2CrO42- + 2H+ yellow

This experiment is used to demonstrate the effects of concentration changes on an equilibrium mixture. (C)

Fe3+

+ CNSyellow

Fe(CNS)2+ red

This experiment is also be used to demonstrate the effects of concentration changes on an equilibrium mixture. In this experiment, the above materials are replaced by everyday non-toxic materials. Objective of lesson: To give students an understanding of the concept of chemical equilibrium and to demonstrate Le Chatelier’s Principle, i.e. if a stress is applied to a system at equilibrium, the system re-adjusts to relieve the stress applied. Part I is do be done as a demo and discussed in class as an introduction to Le Chatelier’s Principle and the concept of equilibrium. Learning Outcomes: At the end of this lesson:  Explain the concept of chemical equilibrium.  Distinguish between static and dynamic equilibrium.  State Le Chatelier’s Principle.  Describe how to set up an experiment that is at chemical equilibrium.  Predict the effect of adding a stress to the system at equilibrium. Materials required:  Candle  1 balloon  Soda water  5 Erlenmeyer Flasks  Black tea  Vinegar  Ammonia – cleaning solution  Tincture of iodine  Starch  Universal indicator  Drinking straw UNAM, School of Pharmacy - Pharmaceutics

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Hot plate Ice bath Glass stirring rods Introduction o You may have come across the word “equilibrium” in your study of physics o If you look up the meaning of “equilibrium” in a dictionary you will find it explained using words like “state of balance”. A meter stick which is suspended at its centre of gravity is said to be balanced or in equilibrium. A meter stick suspended at its centre of gravity remains stationary or static. Thus, this type of equilibrium is often referred to as static equilibrium. In other words, the entire system is not moving. o Consider now the case of a man running on a treadmill. Overall, there is no change in the position of the man. He is running forward at the same speed as the belt is moving in the opposite direction. The two opposing motions balance each other. This is...