Question

what numbers of moles of NaCl and MgCl2 is same?​

Answer 1

First let us know the no. of ions in MgCl2.

The molecular mass of MgCl2 is ( 1 * 24 ) + ( 2 * 35.5 ) = 24 + 71 = 95 a.m.u. .

No. of moles of a substance of atomic mass “a” = (No. of grams in sample)/(molecular mass )

No. of moles in MgCl2 = 245 / 95 = 2.5789474… = 2.579 (approx.) moles .

Now, there are ( 1 * Mg ( +2 ) ) + ( 2 * Cl( -1 ) ) = 3 ions total / molecule .

1 mole = ( Avogradro’s number ) molecules . (Avogadro’s Number = 6.022 * 10 ^ 23)

Therefore , there are a total of 3 * 2.579 * ( Avogadro’s Number ) ions in the sample.

Now ,

The NaCl sample must contain 3 * 2.579 * ( Avogadro’s Number ) ions.

Let its mass = x grams.

Now ,

Molec. Mass of NaCl = ( 1 * 23 ) + ( 1 * 35.5 ) = 58.5 a.m.u.