When performing acid-base titrations, the first step is often a standardization

Question

When performing acid-base titrations, the first step is often a standardization of the titrant, which is an accurate determination of its concentration. Acidic titrants might be standardized in titration of a well-defined amount of a solid base, such as sodium carbonate. In such a procedure, why is it not necessary to know the exact amount of water used in preparation of a solution of Na2CO3 used in standardization of an acid? The standardization of an acid might also be carried out using a solution of a base with known concentration. For example, it is found that 37.60 ml of 0.210 M NaOH are required to neutralize 25.05 ml of H2S04 solution in a titration experiment. Calculate the molarity and normality of the H2S04 solution. In the example given above, the amount of acid to be titrated has to be delivered by a pipet so that its volume is accurately known. However, the solution of the acid is often diluted to facilitate the titration process. Explain why additional de-ionized water might be added without affecting the results of the titration.

Explanation / Answer

when the base Na2CO3 is weighed, number of moles are known and hence it is immaterial as long as the whole sample is used for titration.

from M1V1= M2V2

37.60*0.21 =25.05*M2

M2,Molarity of sulfuric acid = 37.6*0.21/25.05=0.31521M

Normality of H2SO4= 2times its moalrity =2*0.31521=0.6304N

Generally the stock solution used will be of high concentration and this solution need to be diluted for determination of end point more accurately.

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