Measurement of freezing point Depression

The subject of Measurement of freezing point Depression will be discused FREEZING POINT DEPRESSION Relation between Depression of Freezing point and Lowering of Vapour-pressure – The vapour pressure of a pure liquid changes with temperature as shown by the curve ABC, in Fig. – There is a sharp break at …

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Measurement of boiling point elevation

MEASUREMENT OF BOILING POINT ELEVATION – There are several methods available for the measurement of the elevation of boiling point. – Some of these are outlined below : (1) Landsberger-Walker Method This method was introduced by Landsberger and modified by Walker. Apparatus: – The apparatus used in this method is …

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Measurement of lowering of vapour pressure

MEASUREMENT OF LOWERING OF VAPOUR PRESSURE (1) Barometric Method – Raoult measured the individual vapour pressure of a liquid and then the solution by this method. – He introduced the liquid or the solution into Toricellian vacuum of a barometer tube and measured the depression of the mercury level. – …

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Lowering of vapour pressure- Raoult’s law

In this subject we will restrict our discussion to Raoult’s Law COLLIGATIVE PROPERTIES – Dilute solutions containing non-volatile solute exhibit the following properties : (1) Lowering of the Vapour Pressure (2) Elevation of the Boiling Point (3) Depression of the Freezing Point (4) Osmotic Pressure – The essential feature of …

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Solutions of solid substances in liquids

SOLUTIONS OF SOLIDS IN LIQUIDS – Solutions of a solid substance in a solvent are most commonly met with. – The process of solution of a solid substance in a solvent is explained by the electrical forces operating between the molecules or ions of the solute and the molecules of …

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Solutions of liquids in liquids

SOLUTIONS OF LIQUIDS IN LIQUIDS – The solutions of liquids in liquids may be divided into three classes as follows: – We will now proceed to consider the more important properties of these three classes of solutions. SOLUBILITY OF COMPLETELY MISCIBLE LIQUIDS – Liquids like alcohol and ether mix in …

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Ways of Expressing Concentration

Concentration of A Solution – The concentration of a solution is defined as : the amount of solute present in a given amount of solution. – Concentration is generally expressed as the quantity of solute in a unit volume of solution. A solution containing a relatively low concentration of solute …

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Measurement of Optical Activity

Optical Activity – Optical activity is one of imortant physcial properties of liqiuds – A beam of ordinary light consists of electromagnetic waves oscillating in many planes. – When passed through a polarizer (e.g., a Polaroid lens), only waves oscillating in a single plane pass through. – The emerging beam …

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Determination of Refractive Index

Refractive Index – The refractive index (n) of a substance is defined as the ratio of the velocity of light in vacuum or air, to that in the substance: – When a ray of light passes from air into a liquid, its direction is changed. This change of direction is …

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Viscosity – Measurement of Viscosity

Viscosity – Viscosity is the resistance of a liquid to flow. – A liquid may be considered to be consisting of molecular layers arranged one over the other. – When a shearing force is applied to a liquid, it flows. However, the forces of friction between the layers offer resistance …

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Determination of Surface Tension

Surface Tension – Surface Tension property of liquids arises from the intermolecular forces of attraction. – A molecule in the interior of a liquid is attracted equally in all directions by the molecules around it. – A molecule in the surface of a liquid is attracted only sideways and toward …

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Intermolecular Forces in Liquids

 Intermolecular Forces in Liquids Intermolecular forces in liquids are collectively called van der Waals forces. These forces are essentially electrical in nature and result from the attraction of charges of opposite sign.  The principal kinds of intermolecular attractions are: (1) Dipole-dipole attractions (2) London forces (3) Hydrogen bonding.    The relative …

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General Characteristics of Gases

All matter exists in three states: gas, liquid and solid.   A molecular level representation of gaseous, liquid and solid states is shown in the following Fig:     A gas consists of molecules separated wide apart in empty space. The molecules are free to move about throughout the container. …

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