Q17 of 27 Page 1

(a) Complete the following chemical reactions:

(i) Na2Cr2O7 + KCl →


(ii) 2MnO4- + 5SO32- + 6H+→


(b) How does the color of Cr2O72- change when treated with an alkali?


(a) (i) Na2Cr2O7 + 2KCl → K2Cr2O7 + 2NaCl


(ii) 2MnO4- + 5SO32- + 6H+→ 2Mn2+ + 5SO42- + 3H2O


(b) The orange colour of Cr2O72– ion changes to yellow when treated with an alkali because of formation of chromate ion i.e. CrO42-.


Cr2O72– + 2OH-→ 2CrO42– + H2O


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15

Answer the following:

(a) Why is ester hydrolysis slow in the beginning and then becomes faster after some time?


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(c) Give an example of oil in water emulsion.


OR


Define the following:


(a) Associated colloids (b) Electrophoresis (c) Zeta potential


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(a) What is the difference between calamine and malachite? (b) Why is zinc used instead of Cu for recovery of Ag from [Ag(CN)2]- ? (c) What is the role of cryolite in metallurgy of Al?

OR


(a) Give two points of differences between pig iron and cast iron.


(b) Outline the principle of zone refining.


 18

(a) Draw the structures of geometrical isomers of [Fe(NH3)2 (CN)4]-.

(b) [NiCl4]2- is paramagnetic while [Ni(CO)4] is diamagnetic though both are tetrahedral. Why? [Atomic number of Ni = 28]


OR


Define the following:


(a) Ambidentate ligands


(b) Spectro chemical series


(c) Heteroleptic complexes


 19

(a) Write the product formed when (i) 2-chloropropane is treated with alc. KOH. (ii) Aniline reacts with conc. H2SO4 at 453 – 473 K.

(b) When aniline is heated with CHCl3 and alc. KOH, a foul smelling compound is formed. What is this compound?