Chemistry at a Glance

Why equimolar aqueous solution of sodium chloride and sodium sulphate are not isotonic?
Answer in the comment section?

Choose the correct answer
1)Value of Henry's constant KH
a)increases with increase in temperature
b) decreases with increase in temperature
c) remains constant
d) first increases, then decreases
The answer is a

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An Activity Of Class X Chemistry
When ferrous sulphate crystal (green crystal) are heated
1) First a dirty white powder is formed
2) On further heating a brown residue is obtained

FeSO4.7H2O ____________ FeSO4 + 7H2O

2FeSO4 _______________ Fe2O3 +SO2 + SO3

Dirty white powder is anhydrous FeSO4

Brown residue is Ferric Oxide Fe2O3

SO2 and SO3 both are colourless gases

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Raoult's Law for solution for non volatile solutes .
Mathematically
1) Vapour pressure of solution = Vapour pressure of pure solvent x mole fraction of solvent
2)Vapour pressure of solvent - Vapour pressure of solution/ Vapour pressure of solvent=no moles of solute /no. of moles of solute + no of moles of solvent

Mole Fraction
Mole Fraction of a solute in a solution = Number of Moles of solute /Number of Moles of solute+ Number of Moles of solvent.

Mole Fraction of a Solvent = Number of Moles of Solvent/Number of Moles of solute+ Number of Moles of solvent.

Sum of mole Fraction of Solute + Mole Fraction of Solvent = 1

(Mole = Mass / Molar Mass)

Facts about Vapour Pressure:
The vapour pressure of a solution is less as compared to that of pure solvent at the same temperature.
Lowering of vapour pressure = vapour pressure of solvent - vapour pressure of solution.
Relative Lowering of Vapour Pressure = vapour pressure of solvent - vapour pressure of solution / vapour pressure of solvent.

Special tips for the student of H.S 1st year
1) Learn the name of the elements from atomic number 1 ie from Hydrogen to the elements of atomic nos 36 ie Krypton in the Periodic Table.
2) Learn the electronic configuration of these elements.
3) At the same time you should know the general electronic configuration of d - block elements and f- block elements.

Vapour pressure:
Vapour pressure of a liquid or solution is the pressure exerted by the vapours in equlibrium with the liquid or solution at a patricular temperature.
1) Higher the temperature ,greater is the vapour pressure.
2) Weaker are the intermolecular forces in a liquid,greater is the vapour pressure.