Titration question help plz! (1 Viewer)

[Nelly_04]

Can anyone help with this titration question plz:

Q) Phthalic acid is a weak diprotic acid for which we can write the formula as H2(C8H4O4.) Potassium hydrogen phthalate,
KH(C8H8O4) is a good promary standard for standardising alkali solutions. It contains one acidic hydrogen per formula unit. 0.917g of potassium hydrogen phthalate was dissolved in water and titrated with an approximately 0.2mol/L sodium hydroxide solution; 27.2 mL hydroxide solution was needed to reach the endpoint. Calculate the accurate molarity of the hydroxide solution.


Does anyone kno wat this question actually means? How are u supposed to kno which substance is the titrant and which is being titrated? Wat will be the balanced equation? And wat is the purpose of the first sentence? Where does phthalic acid come into it? Can anyone pls write how u work these kind of questions out step by step. Plz help!!!

Thanks

 

[Xayma]

if you react equal moles of Potassium and Phthalic acid it will form mostly Potassium Hydrogen Phthalate.

From then on:

KHC₈H₈O_{4 (aq)}+NaOH_(aq) ----> NaKC₈H₈O_{4 (aq)}+H₂O_(l)

So calculate moles of KHC₈H₈O₄ then stoic it (1:1 ratio) then do concentration.