1.

(i) Derive the relation between pH and pOH (ii) Give three uses of emulsions.

Answer»

Solution :A relation between `pH and pOH` can be established using their FOLLOWING definitions
`pH=-log_(10)[H_3 O^+]""…(1)`
`pOH=-log_(10)[OH^-]""…(2)`
ADDING equation (1) and (2)
`pH+pOH=-log_(10)[H_3 O']-log_(10)[OH^-]`
`=-(log_(10)[H_3O^+][OH^-] +log_(10)[OH^-])`
`pH+pOH=-log_(10)[H_3 O^+][OH^-]`
`[because loga+logb=LOG ab]`
We know that `[H_3O^+][OH^-]=K_w`
`rArr pH+pOH=-log_(10)K_w`
`rArr pH+pOH=pK_w ""[because pK_w=-log_(10)^(K_w)]`
at `25^@ C` the IONIC product of water,
`K_w=1xx10^(-14)`
`pK_w=-log_(10)10^(-14)=14 log_(10)10`
`=14`
`therefore (2) rArr therefore `At `25^@ C, pH +pOH=14`


Discussion

No Comment Found

Related InterviewSolutions