Short Answer Type(a) Why does the presence of an excess of lithium make LiCl crystals pink?
(b) A solid with cubic crystal is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-center. What is the formula of the compound?
How are interhalogen compounds formed? What general compositions can be assigned to them?
Aluminum crystallizes in an fcc structure. Atomic radius of the metal is 125 pm. What is the length of the side of the unit cell of the metal?
The standard electrode potential (E°) for Daniell cell is +1·1 V. Calculate the G° for the reaction
Zn(s) + Cu2+ (aq) ----> Zn+ (aq) + Cu (s)
(1 F = 96500 C mol-1).
(a) For a reaction A + B --> P, the rate law is given by,
r = k [A]1/2 [B]2.
What is the order of this reaction?
(b) A first order reaction is found to have a rate constant k = 5·5 x 10-14 s-1. Find the half-life of the reaction.
Outline the principles of refining of metals by the following methods:
(i) Zone refining
(ii) Vapour phase refining
Principles of refining of metals by:
(i) Zone refining: The impurities are more soluble in the melt than in the solid state of the metal. Hence, the pure metal crystallises out of the melt and impurities pass on into the adjacent molten zone and like this at one end impurities get concentrated. Silicon, indium, boron, gallium etc. can be purified by this process.
(ii) Vapour phase refining: Vapour phase refining is the process of refining metal by converting it into its volatile compound and then, then decomposing it to obtain a pure to carry out this process
(a) The metal should form a volatile compound with an available reagent.
(b) The volatile compound should be easily decomposable so that the metal can be easily recovered.
Nickel, Zirconium, and titanium are using this method.Define the following terms giving an example of each:
(i) Associated colloids
(ii) Lyophilic sol
(iii) Adsorption
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