Ncert Exercises & Solutions

1.25 How are 0.50 mol Na2CO3 and 0.50 M Na2CO3 different?

Molar mass of

{Na}_{2} {CO}_{3}

= (2 × 23) + 12.00 + (3× 16) = 106 g mol–1
Now, 1 mole of

{Na}_{2} {CO}_{3}

means 106 g of

{Na}_{2} {CO}_{3}

.
0.5 mol of

{Na}_{2} {CO}_{3}

\frac{106 g}{1 mole} x 0.5 mol {Na}_{2} {CO}_{3}

= 53 g

{Na}_{2} {CO}_{3}

⇒ 0.50 M of

{Na}_{2} {CO}_{3}

= 0.50 mol/L

{Na}_{2} {CO}_{3}

Hence, 0.50 mol of

{Na}_{2} {CO}_{3}

is present in 1 L of water or 53 g of

{Na}_{2} {CO}_{3}

is present in 1 L of water