Sage-Tips

Why is back titration used for aspirin?

Consider using titration to measure the amount of aspirin in a solution. Using back titration the end-point is more easily recognised in this reaction, as it is a reaction between a strong base and a strong acid. This type of reaction occurs at a high rate and thus produces an end-point which is abrupt and easily seen.

What is the purpose of back titration?

A back titration is used when the molar concentration of an excess reactant is known, but the need exists to determine the strength or concentration of an analyte. Back titration is typically applied in acid-base titrations: When the acid or (more commonly) base is an insoluble salt (e.g., calcium carbonate)

Why do you titrate aspirin?

Part II: Determination of the purity of aspirin tablets Second, you will titrate a sample of your aspirin (acetylsalicylic acid) with the standardized NaOH to determine the moles of acid in a given weight of your product. This will allow you to assess its purity.

Why do we use blank titration in saponification?

A blank titration is carried out by titrating a fixed and known concentration of titrant into a solvent with zero analyte. This allows the amount of reactive substance within the plain solvent to be determined and hence allows a determination of the error in future titration experiments using this solvent.

Why is back titration better than titration?

The main difference between back titration and direct titration is that a back titration determines the concentration of the unknown by determining the remaining amount of the compound with a known concentration whereas a direct titration directly measures the concentration of the unknown compound.

Why is back titration with blank determination necessary?

This is done to ensure that either there are no substances in the solvent which can react with the titrant, or to estimate the amount of titrant that would react with the pure solvent. In this way, we can estimate the error that can be produced when the actual titration experiment is conducted.

What is back titration Why do we employ this type of titration to determine the neutralizing capacity of an antacid?

The excess HCl is titrated with NaOH(aq) until enough OH– (from the NaOH solution) has been added to completely react with the excess H+ (from the excess HCl in the solution). So, part of the added acid is neutralized by the antacid tablet; the remainder is neutralized by the NaOH added. This is called back titration.

What is the titrate in a titration?

To titrate is to measure how much of a substance you have by measuring how much of the solution is required to achieve a given reaction. To determine the concentration of (a solution) by titration or perform the operation of titration.

What is back titration example?

Back titration works in the following manner (with an example) : 1: The substance or solution of unknown concentration (4 gm of contaminated chalk, CaCO3 ) is made to react with known volume and concentration of intermediate reactant solution (200 ml, 0.5N HCl). The reaction goes past the equivalence point.

What is back titration in saponification?

Saponification value is a measure of the content of ester linkages. It is determined by back titration of potassium oxide in the presence of phenolphthalein indicator with 0.5 N sulfuric or hydrochloric acid. 39. First a sample is mixed with 25 ml of alcoholic solution of KOH and left for 1 h in steam bath to react.

What is the difference between titration and back titration?

In a direct titration, you add a standard titrant to the analyte until you reach the end point. In a back titration, you add an excess of standard titrant to the analyte, and then you titrate the excess titrant to determine how much is in excess.

What is the titration method for aspirin?

You cannot use simple titration method since aspirin is a weak acid, the identification of the endpoint will get difficult and the reaction will proceed slowly. The ‘stage one’ of this reaction is of alkaline hydrolysis involving reaction of aspirin solution with a measured amount of sodium hydroxide.

How do you determine the concentration of aspirin in a tablet?

Determination of Aspirin using Back Titration. This experiment is designed to illustrate techniques used in a typical indirect or back titration. You will use the NaOH you standardized last week to back titrate an aspirin solution and determine the concentration of aspirin in a typical analgesic tablet. You will be graded on your accuracy.

What is the purpose of a back titration?

In a back titration, you add an excess of standard titrant to the analyte, and then you titrate the excess titrant to determine how much is in excess. It is often preferable to do a back titration if. one of the reactants is volatile and some might escape during the titration (e.g., NH₃)

What happens when aspirin reacts with a strong acid?

This reaction will be a reaction between a strong base and a strong acid, reacting at high speed and producing an abrupt endpoint result. You cannot use simple titration method since aspirin is a weak acid, the identification of the endpoint will get difficult and the reaction will proceed slowly.