Question

A solution was prepared by dissolving 125.0 g of KCl in 275 g of water. Calculate the mole fraction of KCl. (The formula weight of KCl is 74.6 g/mol. The formula weight of water is 18.0 g/mol.)

Answer 1

The mole fraction of KCl is 0.13

Step-by-step explanation:

no of moles of KCl (n KCl) = W/G.F.Wt

= 135/74.6

= 1.81moles

no of moles of H2O (nH2O) = W/G.F.Wt

= 225/18 = 12.5 moles

mole fraction of KCl ( XKCl) = nKCl/nKCl + nH2O

= 1.81/(1.81+12.5)

= 1.81/14.31

The mole fraction of KCl is = 0.13

Answer 2

The mole fraction of
`KCl` is
`N_(KCl)=0.099`

Step-by-step explanation:

Generally number of mole is mathematically represented as

`n = (mass)/(Molar mass )`

The number of mole of
`KCl` is

`n_(KCl) = (mass \ of \ KCl)/(Molar\ mass \ of \ KCl )`

`n_(KCl) = (125)/(74.6)`

`=1.676 \ moles`

The number of mole of
`H_2O` is

`n_(H_2O) = (mass \ of \ H_2O)/(Molar\ mass \ of \ H_2O )`

`n_(H_2O) = (275)/(18)`

`= 15.28 \ moles`

Mole fraction of
`N_(KCl)= (n_(KCl))/(n_(KCl) + n_(H_2O))`

`= (1.676)/(15.28 +1.676)`

`N_(KCl)=0.099`