Q.

20 mL of sodium iodide solution gave 4.74 g silver iodide when treated with excess of silver nitrate solution. The molarity of the sodium iodide solution is _____ M. (Nearest Integer value)

(Given: Na = 23, I = 127, Ag = 108, N = 14, O = 16 g mol-1)                          [2025]


Ans.

(1)

Molar mass of silver iodide (MAgI)=(108+127)g/mol=235g/mol

Moles of AgI (nAgI)=WAgIMAgI=4.74235mol

NaI(aq)+AgNO3(aq)(excess)  AgI(s)+NaNO3(aq)

As per reaction stoichiometry:  

Moles of NaI (nNaI)=Moles of AgI (nAgI)=4.74235mol

Volume of NaI solution (VNaI)=20mL=0.02L

Molarity of NaI (MNaI)=nNaIVNaI(in L)=4.74235×0.02mol

=1.008 M