Respuesta :

Willchemistry
Mass water = 100 g solution - 10.5 g glucose => 89.5 g of H2O

Molar mass glucose => 180.1559 g/mol

Molality = moles glucose / kg solvent

( 10.5 / 180.1559 ) mol / ( 89.5 / 1000 ) kg =

0.0582 / 0.0895 => 0.650 mol/kg

hope this helps!
   let suppose we have 100g sample solution: 
10.5% by mass, there is 10.5g glucose.
 89.5g is water. 
Molality = moles of solute / kilograms of solvent 
 no of moles= 10.5g glucose/ molar mass (180g) 
= 0.058moles
 0.058mole glucose / 0.089kilograms of water
=0.65molal 
=hope it helps