Molality is defined as 1 mole of a solute in 1 kg of solvent.
Molality=
[tex]\frac{Number of moles of solute}{Mass of solvent in kg}[/tex]
Number of moles of solute, n=
[tex]\frac{Given mass of the substance}{Molar mass of the substance}[/tex]
Given mass of the nitrobenzene=0.2 g
Molar mass of the substance= 123.06 g mol⁻¹
Number of moles of nitrobenzene,
[tex]n= \frac{0.2 }{123.06}[/tex]
Number of moles of nitrobenzene, n= 0.0016 mol
Mass of 10.9 g of naphthalene in kg=0.0109
[tex]Molality= \frac{0.0016}{0.0109 }[/tex]
Molality= 0.146 m
