With regards gravimetric analyses, discuss the following. How crystal growth can

Question

With regards gravimetric analyses, discuss the following. How crystal growth can be achieved. How peptization is prevented A student collected the following data (triplicate analyses) towards potassium permanganate using sodium oxalate as a primary standard of approximately 0 13 g of the sodium oxalate [Na_2(COO)_2] salt was weight about 150 mL of distilled water followed by addition of 20-25 mL of warming the mixture for each titration. 2Mno_4 + 5(COO)_2^2- + 16H* rightarrow 2Mn^2+ + 10CO_2 + 8H_2 O The indicator blank for this titration, where permanganate was used as 0.08 mL. What is a primary standard? Why was it necessary to warm the mixture for the sodium oxalate Why is it important to carry out an indicator blank for the perm

Explanation / Answer

Solution:

1) typically a reagent which can be weighed easily, and which is so pure that its weight is truly representative of the number of moles of substance contained is called as Primary standard. Generally Standards are used in analytical chemistry.

2) The mixture is warmed between 60- 70 C for increasing the activation energy to have high kinetic collision to get result in short time the reason behind this is due to oxalic acid as it not soluble completely in room temperature must have to heated for complete dilution. The another factor is because of slow reaction in room temperature, it shouls not be misunderstood the reaction is thermodynamically controlled its not it is controlled kinetically by activation energy which are gained by warming up of the mixture.

3) Permanganate titrations don't require use of indicators. Permanganate itself has a very intense, purple color, and small excess of the titrant is usually enough to color the solution and to signal end point. That is especially true in the case of 0.1M permanganate solutions, when lower concentrations are used - 0.01M - we may need either blank test or indicator. To make the determination of end point easier we can place a sheet of white paper under the sample flask.

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