(a) Define the terms osmosis and osmotic pressure. Is the osmotic pressure of a solution a colligative property? Explain.
(b) Calculate the boiling point of a solution prepared by adding 15.00 g of NaCl to 250.0 g of water. (Kb for water = 0.512 K kg mol-1), (Molar mass of NaCl = 58.44 g)
(i) NF3 is an exothermic compound whereas NCl3 is not.
(ii) F2 is most reactive of all the four common halogens.
(b) Complete the following chemical equations:
(i) C + H2SO4 (conc.)-->
(ii) P4 + NaOH + H2O-->
(iii) Cl2+F2 ------>
(excess)
(a) Account for the following:
(i) The acidic strength decreases in the order HCl > H2S > PH3
(ii) Tendency to form pentahalides decreases down the group in group 15 of the periodic table.
(b) Complete the following chemical equations:
(i) P4 + SO2Cl2-->
(ii) XeF2 + H2O--->
(iii) I2+HNO3(conc.)--->
Answer the following:
(i) Haloalkanes easily dissolve in organic solvents, why?
(ii) What is known as a racemic mixture? Give an example.
(iii) Of the two Bromo derivatives, C6H5CH(CH3)Br and C6H5CH(C6H5)Br, which one is more reactive in Sn1 substitution reaction and why?
Describe the following giving one example for each:
(i) Detergents
(ii) Food preservatives
(iii) Antacids
Give chemical tests to distinguish between
(i) Propanal and propanone,
(ii) Benzaldehyde and acetophenone.
(b) How would you obtain
(i) But-2-enal from ethanal,
(ii) Butanoic acid from butanol,
(iii) Benzoic acid from ethylbenzene?
(a) Describe the following giving linked chemical equations:
(i) Cannizzaro reaction
(ii) Decarboxylation
(b) Complete the following chemical equations:
(i) Cannizaro reaction
In this reaction, the aldehydes which do not have a -hydrogen atom, undergo self-oxidation and reduction (disproportionation) reaction on treatment with a concentrated alkali.
Example:
(ii) Decarboxylation
The decarboxylation reaction can be carried out either by using soda lime or by electrolysis
Using soda lime: Sodium salts of carboxylic acids when heated with soda lime (NaOH + CaO) in the ratio 3:1) undergo decarboxylation reaction to yield alkanes.
Electrolytic decarboxylation: Electrolysis of aqueous solutions of sodium or potassium salts of carboxylic acids give alkanes having twice the number of carbon atoms present in the alkyl group of acid.
This is known as Kolbe’s decarboxylation.
2RCOONa--> 2RCOO- + 2Na+
H2O-->2OH- + 2H+
At Anode:-
2RCOO- - 2e---> CO2 + R - R
At Cathode:-
2H+ + 2e----> H2
b)