1.

How many moles of `Ca(OH)_(2)` must be dissolved to produce 250 mL of an aqueous solution of pH `10.65`, assuming completer dissociation ?

Answer» Let a mole of `Ca(OH)_(2)` be dissolved in 250 mL. solution to have `pH= 10.65`
`[Ca(OH)_(2)]=(axx1000)/(250)=4a M`
`{:(("Complete ionization"), Ca(OH)_(2)rarr,Ca^(2+)+,2OH^(-)),("Intial moles", 4a,0,0),("Final moleas", 0,4a, 2xx4aM):}`
`:. [OH^(-)]= 8aM`
`[H^(+)]=(10^(-14))/(8a)`
`.: pH= -llog[H^(+)]`
`:. 10.65= -log(10^(-14))/(8a)`
`(10^(-14))/(8a)=2.238xx10^(-11)`
`:. a=5.85xx10^(-5)`mole


Discussion

No Comment Found

Related InterviewSolutions