Determine the volume (in ml) of NaOH (aq) needed to prepare `32.8 gm Na_(3)PO_(4)` by reaction
`3NaOH (aq) + H_(3)PO_(4) (aq) rarr Na_(3)PO_(4) (aq) + 3H_(2)O (l)`
Sodium hydroxide solution is 20% by mass and have density `1.5 gm//ml`.
[Divide your answer by 16]

Answer

5

Explanation

`{:(3NaOH (aq) + H_(3)PO_(4) (aq) rarr,Na_(3)PO_(4) (aq) + 3H_(2) O (l),),(,32.8 gm,):}`
`n_(Na_(3)PO_(4)) = (32.8)/(164) = 0.2` mole
` n_(NaOH)` required `= 0.2 xx 3 = 0.6` mole
Mass of `NaOH = 0.6 xx 40 = 24 gm`
`20 gm NaOH` in 100 gm solution
`20 gm NaOH` in `(100)/(1.5)` ml solution
For 24 gm `NaOH` volume of solution `= (100)/(1.5) xx (24)/(20) = 80 ml`
`= (80)/(16) = 5 ml`