What is reagent grade water?

 Reagent grade water

What is reagent grade water?

Reagent grade water is a pure water that has poor electrical conductivity or very low ions in it.usually called distilled water,de ionized water or milli Q water.

There are three types of reagent grade water besed on difference in electrical conductivity.

Type 1:

Also called grade 1 water.this is ultra pure water having electrical conductivity upto 0.1 micro siemens per centimetre.

Type 2:

This water having electrical conductivity upto 1 micro siemens per centimetre.also called grade 2 water.

Type 3:

This water having electrical conductivity upto 10 micro siemens per centimetre.also called grade 3 water.

Methods of preparation of reagent grade water:

There are two common methods to prepare reagent grade water.

1) Distillation:

Boiling point of water(H2O molecules) is 100 degree celsius.in this process,the water molecules becomes vapour by heating at a particular temperature 🌡️.then condensed by the condensor at low temperature.to get ultra pure water,re distill the distillate.

2)Reverse osmosis:

The water of low and higher concentration is is separated by a semi permeable membrane.when the pressure is applied,the solvent(water molecules) move from higher concentration to lower concentration and the water becomes pure.

Specification for reagent grade water:

There are some specification for reagent grade water.if the water showing deviation from following specification,then it not consider as reagent grade water.

These are the tests performed for reagent grade water specification:

1)PH:

PH of reagent grade water is always 7. But it will show you 5.2 to 5.8 at 25 degree Celsius. because the carbon dioxide present in the atmosphere react with H2O molecules to form carbonic acid which increase the acidic character.Check here how to determine ph and electrical conductivity.

           H2O + CO2   → H2CO3

                   H2CO3  → 2H+ and CO3 2-

2) Electrical conductivity:

Electrical conductivity is the main parameter of water to determine the water is pure or not.low electrical conductivity means low ions.high electrical conductivity means high ions.electrical conductivity of reagent grade water must be negligible.that is why the reagent grade water is called de ionized water.

3)Total solids:

Reagent grade water must be free from suspended particles,settleable matter and dissolved solids.all of they are called total solids.go here to know the determination of total solids.

4)Silica:

Sand is the great source of silica content.because of every type of impure water examined to be pure water,the silica also present even in pure water.so knowing the silica content in reagent grade water is mandatory.

5)Color retention:

Take 500 ml of water sample tested as reagent grade water.add 1 ml concentrated sulfuric acid and 0.2 ml 0.01M potassium permanganate solution.let it for 10 to 60 minutes.if the pink color faded to color less,the water is not pure.

Grade 1 water:

PH = 5.2 to 5.8

Electrical conductivity = upto 0.1 micro siemens per centimetre.

Total solids = Not specified(should not be more than 0.05mg/l

Silica = 0.01mg/l.

Color retention = Passes the test for 60 minutes.

Grade 2 water:

PH = 5.2 to 5.80

Electrical conductivity = upto 1.0 micro siemens per centimetre.

Total solids = 0.5mg/l.

Silica = 0.1mg/l.

Color retention = Passes the test for 10 minutes.

Grade 3 water:

PH = 5.2  to 5.95

Electrical conductivity = upto 5.0 micro siemens per centimetre.

Total solids = 2.0mg/l.

Silica = 1.0mg/l.

Color retention = Passes the test for 10 minutes.

Importance:

Reagent grade water is used widely in analytical chemistry of qualitative and quantitative analysis.Without reagent grade water,we cannot perform the analysis.

For washing glass wares:

In quantitative and qualitative analytical methods,washing of all glass ware with reagent grade water is mandatory.if don't,the ions from glass wares interfere with testing samples.

 As a blank:

In the analysis of samples,the reagent grade water is used as a blank for the confirmation of no ions in it or testing sample will be correct.in UV spectroscopy,the blank water is always used.

To dilute samples:

If we want to reduce the concentration of any sample,the dilution is needed done by reagent grade water.

For preparing reagents and  solutions:

Very important thing the word "reagent" from grade water is used for its importance in the preparation of reagents and solutions used for the quantitative analysis.without reagent grade water,we cannot make reagent and solutions.

Facts about reagent grade water related to current:

We know don't touch the electric switch with wet hands,current shocking through water,etc.but these happenings occuring only with water containing ions.they conducting current.

Only H2O molecules called pure water or reagent grade water do not conducting current through it because no ions in it.if u touch the reagent grade water that connected to electric current,you won't get shocked.

Difference between reagent grade water and normal water:

Many people's confused with normal water and reagent grade water.

normal water contains H2O molecules with other ions.reagent grade water contains only H2O molecules with few ions.

normal water is contaminated,containing invisible or visible solids.reagent grade water is not contaminated.

Normal water conducts electricity.grade water does not conduct electricity.

Physical properties of reagent grade water:

The meaning of water is H2O molecules.so the physical properties of water is only belongs to reagent grade water!.

The chemical formula = H2O

               Melting point = 0 degree Celsius.

                Boiling point = 100 degree Celsius.

                         Density = 0.9998396 g/ml.

Drinking of reagent grade water:

For our daily life we drinking ions containing water.what if we drink ions less reagent grade water?

Our body needs some ions like sodium,potassium or iron for metabolism.in case of absense of these ions,we go weak or die.

Great solvent:

We know water is a universal solvent.especially the reagent grade water has more capacity to dissolve more ions and quickly.you can find solubility of every salt only with reagent grade water or pure H2O molecules.