. Estimation of sodium hydroxide Aim : To estimate the amount of sodium hydroxide dissolved in ml of the given unknown solution volumetrically. For this you are given with a standard solution of sodium carbonate solution of normality . N and hydrochloric acid solution as link solution.
Principle: Neutralization of Sodium carbonate by HCl is given below. To indicate the end point, methyl orange is used as an indicator. Na CO + 2HCl 2NaCl + CO + H O → Neutralization of Sodium hydroxide by HCl is given below. To indicate the end point, phenolphthalein is used as an indicator.
NaOH + HCl NaCl + H O → Short procedure: s.no Content Titration-I Titration-II Burette solution HCl ( link solution) HCl ( link solution) Pipette solution ml of standard Na CO solution ml of unknown NaOH solution Temperature Lab temperature Lab temperature Indicator Methyl orange Phenolphthalein End point Colour change from straw yellow to pale pink Disappearance of pink colour Equivalent weight of NaOH = Procedure : Titration–I (Link HCl )Vs ( standard Na CO ) Burette is washed with water, rinsed with HCl solution and filled with same HCl solution up to the zero mark. Exactly ml of standard Na CO solution is pipetted out into the clean, washed conical flask. To This solution to drops of methyl orange indicator is added and titrated against HCl link solution from the burette. HCl is added drop wise till the colour change from straw yellow to pale pink.
Burette reading is noted and the same procedure is repeated to get concordant values. organic organic - - - - Titration –I (Link HCl )Vs ( standard Na CO ) s.no Volume of standard Na CO (ml) Burette readings Concordant value (Volume of HCl) (ml) Initial (ml) Final (ml) Calculation : Volume of HCl (link) solution V = ml Normality HCl (link) solution N = ? N Volume of standard Na CO