Question

How many moles of ions are there in 2.5 mole of NaCl

Answer 1

remember a trick that if both have same no.of atoms then moles will be same in both,as same of compound.

Answer 2

the number of moles of NaCl = 2.5
molecular mass of NaCl = 23 + 35.5 = 58.5amu

so n = given mass ÷ molecular mass
2.5 = w ÷ 58.5
so w = 2.5 * 58.5
w = 146.25gm

% age of Na+ ion = (23 ÷ 58.5)*100
39.31%

%age of Cl- ion = 100 - 39.31 = 60.69%

so n(Na+) = given weight ÷ molecular weight

n = 39.31% of 146.25 ÷ 23
n = 57.49÷ 23
n = 2.5mol

similarly
n(Cl-) = 60.69% of 146.25 ÷ 35.5
n = 88.76 ÷ 35.5
n = 2.5 mol

hope it helps