Solution |Bunarybliquid| chromatography|

Power point presentation on solution

1. SOLUTION: A solution or a true solution is a homogenous mixture of two or more substances , whose composition can be varied within certain limits. a homogenous mixture means that its composition and properties are uniform throughout the mixture . the component that is present in the largest quantity is known as solvent. one or more components present in the solution other than solvent are called solutes.

2. Solvent determines the physical state in which solution exists . eg. lemon water , air , etc. Important characteristics of true solution are as follows A solution is a single phase system. A solution does not allow a beam of light to scatter and the particles of solute in solution cannot be seen by naked eye. A solution is stable and the solute from the solution cannot be separated by filtration process. Solution is completely uniform , hence its properties are similar, eg. density , refractive index. The composition of solution is variable and can be changed within certain limits of temperature and pressure.

3. types of solution : On the basis of quantity of components , solutions are classified in the following way it is the solution containing the maximum possible quantity of solute dissolved in a solvent at a certain temperature. lower quantity of solute than saturated solution is dissolved in this solution . TWO TYPES : • • solution containing lower quantity of solute. solution containing higher quantity of solute but still lower than the quantity of a saturated solution.

4. □ at constant temperature , quantity of solute is greater than in saturated solution is known as supersaturated solution. ii On the basis of physical states of components, there are three types of solution

5. CONCENTRATION OF SOLUTION : The concentration of a solution is defined as the relative amount of a solute present in a solution . It is generally expressed as the amount of solute present in a unit volume of solution . VARIOUS EXPRESSION FOR THE PERCENTAGE CONCENTRATION OF SOLUTION CAN BE SUMMARISED AS 1. The mass percentage of a component in a given solution is the mass of the component per 100 g of the solution.

6. ii the volume percentage is the volume of the component per 100 parts by volume of the solution .

7. iii It is the mass of solute dissolved in 100 ml of the solution .

8. iv when a solute is present in trace quantities the concentration is expressed in parts per million .

9. v It is the amount of solute which is dissolved in 10 power 9 pats of a solution .

10. viii It is the number of moles of the solute dissolved in 100 g of the solvent. Molarity is independent of temperature unit of molarity is mol/kg of solvent

11. ix Normality is the number of gram equivalents of substance dissolved per litre of the solution . Normality changes with temperature since it involves volume. Unit = gram equivalents per litre .

12. vi Strength in g/L represent the number of grams present in 1L of solution . Strength of solution = mass of solute /volume of solution vii It is the ratio of the number of moles [n] of one component to the total number of moles of solute and solvent. solute = solute/ solute + solvent X solvent = n solvent / n solute + n solvent sum of mole fractions of solute and solvent is always unity X solute + X solvent = 1

13. BINARY LIQUIDS A binary liquid is a mixture of two liquids that can be either completely miscible (like water and ethanol) or partially miscible, forming two distinct phases(like oil and water). The behaviour of binary liquids is often described using concepts like Raoult’s law, ideal and non ideal solutions, and phase diagram. Binary liquid mixture are common in various fields, including chemistry, physics and engineering.

14. VAPOR PRESSURE The vapor pressure of a liquid is the pressure exerted by its vapor over the liquid surface when the liquid and vapor are in dynamic Equilibrium. VP=Kp for A(liq) A(vap) Thus it depends only on temperature for a given liquid.

15. BOILING POINT AND FACTOR AFFECTING The boiling point is the temperature at which the vap pressure and the external pressure are in equilibrium is known as boiling point. Volatile liquids have high vap pressure and low boiling point. Example- Ether, Methyl Alcohol etc. Less volatile liquids have low vap pressure and high boiling point. Example- Water, Aniline, Nitrobenzene

16. RAOULT’ s LAW FOR VOLATILE SOLUTE The partial pressure of volatile component of a solution is directly proportional to its mole fraction in solution at any temperature.

17. MOLE FRACTION IN VAPOR PHASE

18. LIMITATION OF RAOULT’ s LAW It is applicable for dilute solution only. It is applicable for solutions containing solutes, which neither associates nor dissociate. It is applicable for ideal solution only.

19. IDEAL AND NON- IDEAL SOLUTION

20. DISTILLATION This method is used , if organic liquid is stable at its boiling point and contains a non- volatile impurity. when the given liquid is heated to its boiling point ,it is converted into vapours and the vapours on cooling condense to give back the original liquid in its pure form . cool LIQUID VAPOUR LIQUID Liquid such as benzene, toluene , ethanol , acetone , chloroform , carbon tetrachloride can be purified by simple distillation . The liquid obtained is called distillate . This method can be of various types depending upon the conditions and methodology used.

21. TYPES OF DISTILLATION 1 SIMPLE DISTILLATION : When liquid sample has non- volatile impurities or when the difference in boiling points of components is 80 degree or more. eg. Mixture of chloroform [bp 334K] and aniline [bp 457K] Ether and toluene , hexane and toluene etc.

22. 2 FRACTIONAL DISTILLATION : When the difference in boiling points of two liquids are not too much , i.e. vapours of both the liquids are formed almost simultaneously . in such cases fractional distillation technique is adopted. eg. Crude oil in petroleum industry , mixture of acetone and methyl alcohol. The difference between the boiling point of different components in these cases is 10- 15K

23. PROCEDURE Apparatus needed for fractional distillation includes a round- bottomed flask, burner, condenser, adapter, receiver and fractionating column. We also need a mixture of liquids with different boiling points. The fractionating column consists of a long glass tube with a wide bore either packed with glass beads, small stones, porcelain rings or coke or blown into several spherical or pear- shaped bulbs. The actual purpose of the fractionating column is to increase the cooling surface area and to provide hurdles or obstructions to the ascending vapours and descending liquid. There are various types of fractionating columns used in the laboratories. Given below is the stepwise procedure of the fractional distillation:Apparatus needed for fractional distillation includes a round- bottomed flask, burner, condenser, adapter, receiver and fractionating column. We also need a mixture of liquids with

24. Step 1:- The mixture of liquids is heated in a round- bottomed flask, and the vapours rise and enter the fractionating column. Step 2:- The vapours then move to the condenser where the temperature is low. Step 3:- The vapours cool down and get converted into liquid form. Step 4:- The receiver collects the distilled liquid.

25. 3 DISTILLATION UNDER REDUCED PRESSURE [VACUUM]: When liquid boils at higher temperature and it may decompose before is boiling point then distillation under reduced pressure is used. A liquid boils at a temperature when its vapour pressure equalises to the external pressure . But if the liquid decomposes at its boiling point then it can be made to boil at lower temperatures by the application of reduced pressure. eg. Recovery of glycerol from spent- lye, concentration of sugar juice in sugar industry.

26. 4 STEAM DISTILLATION : When the substance is immiscible with water and is steam- volatile, it can be purified by distillation in a current of steam called steam distillation . This technique of purification is applicable to only those organic compounds which are steam volatile. eg. Aniline is separated from water , ortho and para- nitrophenols.

27. 5 CHROMATOGRAPHY :[CHROMA - COLOR , GRAPHY - WRITING] It is the modern technique used for separation and purification of organic compounds. It is discovered by Tswett in 1906. Chromatographic separation depends on the differences in the partition coefficients of the components of a mixture between two immiscible phases. which moves relative to the other.i.e. the . The substances being separated are transported with the mobile phase. The partition coefficient K of a substance , in such a two phase system is given by K = Cs/Cm

28. Cs = concentration of the substance in the stationary phase Cm = concentration of the substance in the mobile phase Thus , greater the partition coefficient of a substance , greater would be its concentration in the stationary phase As a result of this , retention in the stationary phase would be higher and its movement with the mobile phase would be slower.

29. CLASSIFICATION OF CHROMATOGRAPHY Based on the physical state of the mobile and stationary phases

30. Adsorption chromatography This method is based upon the different rates of adsorption of different compounds by an absorbent . Silica gel and alumina are generally used as adsorbent in this process. When the mobile phase is passed over the stationary phase the components of the mixture are moved to different distances over the stationary phase and thus, they can be separated or identified.

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33. CONDUCTANCE The property of a medium which tells about ease with which current flows through the medium is called conductance. CONDUCTANCE [G] = 1/resistance[R] Unit = ohm- 1 , mho , Siemen[S]

34. CONDUCTOMETRY

35. ELECTRO MOTIVE FORCE Electromotive force is defined as the electric potential produced by either an electrochemical cell or by changing the magnetic field. EMF is the commonly used acronym for electromotive force. A generator or a battery is used for the conversion of energy from one form to another. In these devices, one terminal becomes positively charged while the other becomes negatively charged. Therefore, an electromotive force is a work done on a unit electric charge. Electromotive force is used in the electromagnetic flowmeter which is an application of Faraday’s law.

36. The electromotive force symbol is ε. FORMULA ε = V + Ir Where, V is the voltage of the cell I is the current across the circuit r is the internal resistance of the cell ε is the electromotive force

37. POTENTIOMETRY Potentiometry is the field of electro analytical chemistry in which potential is measured under the condition of no current flow. It is method of analysis in which we determine the concentration of solute in solution, and the potential difference between two electrode. Potentiometry is an instrument that used for the determination of unknown concentration between the reference solution an the sample.

38. PRINCIPLE OF POTENTIOMETRY The principle of potentiometry is when the pair of electrodes is placed in the sample solution it shows the potential difference by the addition of titrants. In this way a potential difference is setup between electrode and solution. REFERENCE ELECTRODE - A reference is a half - cell having a known and constant potential. Example Standard Hydrogen Electrode, Silver – Silver Chloride Electrode.

39. INDICATOR ELECTRODE – An indicator electrode is another half cell with unknown potential. Immersed in analyte solution. Its potential is sensitive to the concentration of analyte. Potential is directly proportional to the ion concentration. Example metal electrode, ion selective electrode.

40. REFERENCE www.cemicool.com https://link.aps.org https://tech.chemistrydocs.com NCERT TEXTBOOK AAKASH MODULE

41. THANKS