Molarity vs. molality - 1 | Chemical Calculations for Solutions

What mass of Na2SO4 is needed to make 3.2 L of 2.5 M solution?

nNa2SO4 = Msol x Vsol    and     nNa2SO4 = $\frac{{\mathrm{m}}_{\mathrm{Na}2\mathrm{SO}4}}{{\mathrm{M}}_{\mathrm{Na}2\mathrm{SO}4}}$

⇒ $\frac{{\mathrm{m}}_{\mathrm{Na}2\mathrm{SO}4}}{{\mathrm{M}}_{\mathrm{Na}2\mathrm{SO}4}}$ = Msol x Vsol

mNa2SO4 = Msol x Vsol x M Na2SO4

mNa2SO4 = 2.5 x 3.2 x (23 x 2 + 32 + 4 x 16) = 1.1 x 103 g = 1.1 kg