How is standard solution of sodium hydroxide is prepared?

Sodium Hydroxide Solution Preparation Take about 100ml of distilled water in a cleaned and dried 1000 ml volumetric flask. Add about 4.2 gm of Sodium hydroxide with continues stirring. Add more about 700ml of distilled water, mix and allow to cool to room temperature. Make up the volume 1000 ml with distilled water.

What is standard solution of sodium hydroxide?

Sodium hydroxide is a common and useful strong base. Special care is required to prepare a solution of sodium hydroxide or NaOH in water because considerable heat is liberated by the exothermic reaction….Recipes for Common NaOH Solutions.

	M of solution	Amount of NaOH
F.W. 40.00	1 M	40 g
	0.5 M	20 g
	0.1 M	4.0 g

Why does sodium hydroxide have to be standardized?

But when it comes to anything analytical where you start to involve calculations, standardization is a must. This is done with NaOH because it’s hygroscopic and readily sucks up the moisture in the air. So what is being weighed isn’t totally NaOH, but also the moisture that it has absorbed.

Why is it necessary to prepare a standard solution?

In analytical chemistry, a standard solution is a solution containing a precisely known concentration of an element or a substance. A known mass of solute is dissolved to make a specific volume. Standard solutions are used to determine the concentrations of other substances, such as solutions in titration.

What are the apparatuses used in the preparation of a standard solution?

volumetric flask
To prepare a standard solution, a piece of lab equipment called a volumetric flask should be used. These flasks range in size from 10 mL to 2000 mL and are carefully calibrated to a single volume. On the narrow stem is a calibration mark.

Why sodium hydroxide should be weighed as fast as possible during preparation?

Sodium hydroxide, being a hygroscopic substance absorbs moisture from the atmosphere. Thus, sodium hydroxide cannot be accurately weighed and so a standard solution of Na OH cannot be prepared.

What type of substance can be used for preparing standard solution?

Answer: A standard solution is a solution of accurately known concentration. A standard solution can be prepared by dissolving a primary standard in a suitable solvent (such as distilled water).

Why should the standardized NaOH solution be kept?

Because when atmospheric carbon dioxide came in contact with the stored NaOH, it will react with it and form the carbonic acid. As an outcome, the concentration of the base is reduced. Hence, to avoid the contact with atmospheric carbon dioxide with NaOH it should be kept in stoppered bottle.

What is the possible error that might be occur during preparation of a standard solution?

It can be either of end point error, misreading volumes, concentrations, faulty use of equipment, contaminated glass ware, etc. Some of errors are : Misjudging the color of the indicator near the end point – this is probably the most common one.

Why are common alkalis not used for the preparation of a standard alkali by direct weighing?

Because the accurate concentration of acid has been derived using a primary standard, the acid is referred to as a secondary standard. Similarly, alkali hydroxides such as sodium hydroxide are unsuitable for use as primary standards because they absorb moisture and carbon dioxide from the atmosphere.

How do you prepare a standard solution of sodium hydroxide?

The way you prepare a standard solution of sodium hydroxide is by weighing fast, aiming for the desired concentration, dissolving it in boiled water (so it has no carbon dioxide), keeping the solution protected from carbon dioxide, and standardizing it against a primary standard. The procedure can be found on the USP (United States Pharmacopeia).

Why are pellets of sodium hydroxide not pure NaOH?

Therefore, pellets of sodium hydroxide aren’t pure NaOH and a standard solution can’t be prepared by dissolving a known mass of NaOH in a known volume of water. Solutions must be titrated with a standard solution of acid. Well, such solutions would not have a very long shelf-life.

Is it possible to prepare a standard solution of NaOH by weighing?

So it is not advisable to prepare a standard solution of NaOH by weighinh it. NaOH is a deliquescent substance. It absorbs water when exposed to atmosphere. This will give out difficult while weighing exact amount of the solid. Therefore, standard solution is prepared from a solution of known strength.

Why can’t we measure the mass of sodium hydroxide?

For a start, sodium hydroxide is strongly hygroscopic, and if you put out a few pellets of caustic soda in the air, the solid will DELIQUESCE due to atmospheric moisture. And thus there is the PRACTICAL difficulty of measuring a mass of caustic.

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