(b) Name the law or principle confirmed by the following observations :
(i) When water is added to 0.01M aqueous solution of acetic acid the number of hydrogen ions increase.
(ii) When 96500 coulombs of electricity is passed through acidulated water, 5.6 litres of oxygen at s.t.p. is liberated at the anode.
Arrange Ag, Cr and Hg metals in the increasing order of reducing power. Given :
E° Ag+/Ag = +0.80V E° cr+3/cr = -0.74V E° Hg2/Hg = +0.79V
In a first order reaction, 10% of the reactant is consumed in 25 minutes. Calculate :
(i) The half-life of the reaction.
(ii) The time required for completing 17% of the reaction.
(a) Explain giving reasons why (Give equations in support of your answer):
(i) A solution of NH4Cl and NH4OH acts as a buffer.
(ii) Cu is precipitated as CuS while Zn is not precipitated when H2S is passed through an acidic solution of Cu(NO3)2 and Zn(NO3)2 respectively.
(i) What is Schottky defect in a solid?
(ii) A bcc element (atomic mass 65) has a cell edge of 420 pm. Calculate its density in gms / cm3.
(i)Give Lewis’ definition for acids and bases.
(ii) The solubility of Ag2CrO4 at 25°C is 8.0 x 10-5 moles /litre. Calculate its solubility product.
i) Lewis acid: A compound or an ionic species which can accept a pair of electron known as lewis acid.
Lewis base: A compound or an ionic species which can donate a pair of electron known as lewis base.
ii) Ag2CrO4 ⇌ 2Ag+ + CrO42‒
S 2s s
Ksp = [Ag+ ]2 [CrO42‒] = (2s)2 (s)
= 4s3 = 4 x (8 x 10‒5 )3 = 2.048 x 10‒12