An element with molar mass 27 g mol-1 forms a cubic unit cell with edge length 4.05 x 10-8 cm . If its density is 2.7 g cm-3 , what is the nature of the cubic unit cell?
How would you account for the following?
Actinoid contraction is greater than lanthanoid contraction.
For a reaction A + B → P, the rate is given by Rate = k[A] [B]2
(i) How is the rate of reaction affected if the concentration of B is doubled?
(ii) What is the overall order of reaction if A is present in large excess?
A first order reaction takes 30 minutes for 50% completion. Calculate the time required for 90% completion of this reaction.
(log 2 = 0.3010)
For the given first order reaction the rate constant for 50% completion is given by
Here t= time taken for 50% completion =30 min
[R]0 = initial concentration of the reactant
[R] =final concentration of the reactant
Let [R]0 be 100 and due to 50% completion of the reaction [R] will be 100-50 i.e. 50
Putting value in 1 we get
For same reaction the time required for 90% completion of the reaction can be computed using the expression
Here [R] = final concentration of reactant=100-90 =10
So we have
Therefore the time required for 90% completion of the given first order reaction is 100.13min.
Account for the following:
(i) Acidic character increases from HF to HI.
(ii) There is a large difference between the melting and boiling points of oxygen and sulphur.
(iii) Nitrogen does not form pentahalide.