Question

A `17.2*g` mass of ethylene glycol was dissolved in a `500*g` mass of water to give a solution of `515*mL` volume. What are....?

`"(i) Molarity..."`
`"(ii) Molality..."`
`"(iii) Percentage by mass..."`
`"(iv) Moles fractions of each component..."`

Answer 1

`"Moles of solute"` `=` `(17.2*g)/(62.07*g*mol^-1)=0.277*mol`

Explanation:

`"Molarity"="Moles of solute"/"Volume of solution"=(0.277*mol)/(0.515*L)`

`~=0.50*mol*L^-1`

`"Molality"="Moles of solute"/"Kilograms of solvent"=(0.277*mol)/(0.500*kg)`

`~=0.50*mol*kg^-1`

`"Percentage by mass"` `=` `"Mass of solute"/"Mass of solution"xx100%`

`=(17.2*g)/(17.2*g+500*g)xx100%=3.33%(m/m)`

`"Mole fraction, "chi_"diol"` `=` `"Moles of diol"/"Moles of diol + moles of solvent"`

`=(0.277*mol)/(0.277*mol+(500*g)/(18.01*g*mol^-1))~=0.001`

What is `chi_"water"`?