Why is NaOH Standardised?

In order to have accurate solutions of NaOH, you must standardize the solution. The best way of doing this is to use a primary standard, which is a solid acid that can be weighed. To have a good primary standard it should not absorb anything readily from the air.

Why is NaOH not a primary standard solution?

Sodium hydroxide cannot be used to prepare a primary standard titration solution because the compound is not available in high purity. The most common impurity is water because sodium hydroxide is hygroscopic, meaning it absorbs water from the air.

What is a secondary standard substance?

Secondary Standard Substance : The substance which can not kept on open place and they easily react with the components of air (O2, CO2 etc.), react with balance when they are weighting are called Secondary Standard Substance. e.g. HCL, H2SO4, NaOH, KOH, KMnO4, etc. are the Secondary Standard Substance.

Why HCl is a secondary standard substance?

HCl Secondary Standard. A HCl solution is used as it can be prepared accurately and is quite stable. Because of this stability it is called a secondary standard.

Is NaOH a primary standard?

NaOH has no criteria given above. It is not suitable for the primary standards because they absorb the moisture from the atmosphere. It also absorbs carbon dioxide from the atmosphere. Hence, NaOH is not a primary standard because it has no quality of primary standard.

Which of the following is the best primary standard for the titration of NaOH?

A commonly used primary standard for titration with sodium hydroxide solution is the weak acid potassium hydrogen phthalate or KHP (C8H5O4K). In this reaction as well, one mole of KHP completely reacts with one mole of NaOH. The titration of NaOH with KHP involves adding NaOH from the burette to a known volume of KHP.

Why are secondary standards needed?

Secondary standard in turn is used for the purpose of calibration of control material in smaller lab for analysis of unknown concentration of a substance. So basically, secondary standard serves the purpose of external quality control for smaller labs.

Why are NaOH and HCl not used as primary standards?

Answer Expert Verified Primary standard solutions should be such that their concentration values should be known exactly. They should not attract gases or water vapour from air and react with them. They should not evaporate and emit gases into air. HCl, Na OH do not satisfy these conditions.