(i) A solution is prepared by dissolving 15g of NaCl in 85 g of water. Calculate the mass percentage of solute.
(ii) Calculate the `p_(H)` of 0.001 M NaOH.

Explanation

(i) Mass of solute=15g
Mass of solvent=85g
Mass percentage`=("Mass of the solute")/("Mass of the solution")xx100`
`=(15)/(15+85)xx100=(15)/(100)xx100=15%`
(ii) `[OH^(-)]=`Normality=Molarity`xx`acidity
`=0.001xx1=1xx10^(-3)`
`pOH=-log_(10)[OH^(-)]`
`=-log_(10)^(1)xx[10^(-3)]`
`=-log_(10)^(1)xxlog_(10)10^(-3)`
`=0-(-3log_(10)^(10))`
`pOH=3`
`pH=pOH=14`
`pH=14-pOH=14-3`
`pH=11`
(iii) `n=0.01` mole, `mu=18g" "mol^(-1),W=?`
`W=nxxM`
`=0.01xx18=0.18g`