In: Chemistry
. Give the concentration of the following in terms of Molarity.
a. The molarity of hydroxide ions in a 4.25M solution of barium hydroxide.
b. The molarity of sodium ions in a 11.5M sodium phosphate solution.
a) Here we are dissolving Ba(OH)2 ,then finding out concentration of hydroxide ion in the aqueous solution.
            
Ba(OH)2   +   
H2O   
    
Ba2+     +     
2 OH-
Molarity of Hydroxide ion (OH-) :-
So molarity of OH-
ion in 4.25 M solution of Ba(OH)2 solution is 8.5 M
.
b) Sodium phosphate are salt of sodium (Na+) and phosphate(PO43-) , some examples are:-

Here I am calculating concentration of sodium in sodium dihydrogen sulphate (NaH2PO4).
            
NaH2PO4 +   
H2O   
    
Na+     +     
H2PO-4
Molarity of sodium ion (Na+) :-

So molarity of Na+ ion in 11.5 M solution of NaH2PO4 solution is 11.5M .Similarly you can calculate sonium ion concentration in other sodium phosphate by considering 2 or 3 mol of sodium ion.