--%>
Assignment Help - homework help

What is Elevation in boiling point?

The boiling of a liquid may be defused by the temperature at which its vapour pressure which is equal to atmospheric pressure. The effect of addition in a non-volatile solute on the boiling point shown and its solution containing non-volatile solute with temperature are represented by the curves AB and CD respectively. It is evident by the curves temperature the vapour pressure of solutions is lower than that of the pure solvent and thus, the vapour pressure.

Curve for solution runs below that of the pure solvent. At temperature T0, the vapour pressure of the pure solvent becomes equal to the atmospheric pressure. Thus, the atmospheric pressure and therefore, it is necessary to heat the solution to a higher temperature sayT1 in the atmospheric pressure. Thus, it is clear that the solution in higher temperature than the pure solvent. Evidence T1 - T0 (or Δ Tb)is the elevation in boiling point vapour pressure (Δp), the elevation in the boiling point is also proportional to the solute concentration. Thus,

ΔTb ∝ Δp

According to Raoult's law, Δp ∝ xB

∴ ΔTb ∝ xB

1444_elevation in boiling point.png 

1084_elevation in boiling point1.png 

1730_elevation in boiling point2.png 

1333_elevation in boiling point3.png 

If WA is the mass of solvent in kg, then  1283_elevation in boiling point4.png is equal to molality (m) of the solution

ΔTb = kMA m

Here, k and MA are constants and hence their product, i.e. kMA is replaced by another constant K2.

ΔTb = Kb m, where Kb is called boiling point-elevation constant or molal elevation constant or molal ebullioscopic constant.

As elevation in boiling point depends upon the relative number of moles of solute and solvent but does not depend upon the nature of solute, so it is a colligative property.

   Related Questions in Chemistry

  • Q : Problem on distribution law The

    The distribution law is exerted for the distribution of basic acid among: (i) Water and ethyl alcohol (ii) Water and amyl alcohol (iii) Water and sulphuric acid (iv) Water and liquor ammonia What is the right answer.

    		•
  • Q : Explain oxygen and its preparation.

    Karl Scheele, the Swedish chemist, was

    		•
  • Q : Describe Enzyme Catalyzed reactions

    Many enzyme catalyzed reactions obeys a complex rate equation that can be written as the total quantity of enzyme and the whole amount of substrate in the reaction system. Many rate equations that are more complex than first and se

    		•
  • Q : What are heterogenous catalysis? Give

    When the catalyst exists in a different phase than that of reactants, it is said to be heterogeneous catalyst, and the catalysis is called heterogeneous catalysis. For example, SO2 can be oxidized to SO3

    		•
  • Q : Molarity based question Help me to

    Help me to solve this problem. 4.0 gm of NaOH are contained in one decilitre of solution. Its molarity would be: (a) 4 M (b)2 M (c)1 M (d)1.5 M

    		•
  • Q : Reactivity of allyl and benzyl halides

    why allyl halide and haloarenes are more reactive than alkyl halide towards nucleophilic substitution

    		•
  • Q : Chem Silicon has three naturally

    Silicon has three naturally occurring isotopes. 28Si, mass = 27.976927; 29Si, mass = 28.976495; 30Si, mass = 29.973770 and 3.10% abundance. What is the abundance of 28Si?

    		•
  • Q : Describe the properties of the

    Briefly describe the properties of the carbohydrates?

    		•
  • Q : Finding Active mass of urea Can someone

    Can someone please help me in getting through this problem. 10 litre solution of urea comprises of 240 gm urea. The active mass of urea is: (i) 0.04 (ii) 0.02 (iii) 0.4 (iv) 0.2

    		•
  • Q : Question related to colligative

    The colligative properties of a solution depend on: (a) Nature of solute particles present in it (b) Nature of solvent used (c) Number of solute particles present in it (d) Number of moles of solvent only

    		•