Comment on each of the following observations:
The mobilities of the alkali metal ions in aqueous solution are Li+ < Na+ < K+ < Rb+ < Cs+
Answers
As we move down the group, the ionic and atomic size of the metals increase. The given alkali metal ions can be arranged in the increasing order of their ionic sizes as:
Li+ < N+ < K+ < Rb+ < Cs+
Smaller the size of the ion, more highly it is hydrated. Since Li+ is the smallest in size, it becomes hydrated in the solution. On the other hand, Cs+ is the largest in size and so it is the least hydrated. Hence, the extent of hydration decreases in the order:
Li+ > Na+ > K+ > Rb+ > Cs+
Greater is the mass of the hydrated ion, lower will be its ionic mobility. Hence, Li+ ion has lower ionic mobility and Cs+ has higher ionic mobility. Thus, the given alkali metal ions can be arranged in the increasing order of their mobilities as:
Li+ < Na+ < K+ < Rb+ < Cs+
Answer: SMALLER THE SIZE OF ION ,LARGER IT GETS HYDRATED
HENCE IT'S MOBILITY REDUCES
Explanation: