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unit 3b

how do we prepare a standard solution????
Reply 1
Avatar for Pigster
Pigster
20
Measure the mass of a solute.
Bash it into a volumetric flask.
Add some solvent, shake to dissolve.
Make up the solvent to the mark on the flask, ensuring the bottom of the meniscus is in line with the mark.
Shake.
w00t
Original post by Pigster
Measure the mass of a solute.
Bash it into a volumetric flask.
Add some solvent, shake to dissolve.
Make up the solvent to the mark on the flask, ensuring the bottom of the meniscus is in line with the mark.
Shake.
w00t

but dont we need to kno the concentration of the standard solution well ???
Reply 3
Avatar for Pigster
Pigster
20
You know the mass of the solute. You know the Mr of the solute. Therefore you know the amount.

You know the volume of the solution. Therefore you know the concentration.

The solution in the volumetric flask IS the standard solution.
Original post by pondsteps
how do we prepare a standard solution????


Don't forget that not all compounds can be used to make a standard solution. The solute must have certain characteristics to be considered for a primary standard solution:

1. It must be available in a highly pure form (Analar, for example)
2. It must be stable in the environment (not hygroscopic, deliquescent or efflorescent) and aqueous solution.
3. It should have a relatively high molar mass (preferably)
4. It must react quantitatively with the required compounds.
5. It must be soluble (yes, obvious, I know)

Seconday standards must themselves be determined using primary standard solutions before use.
Original post by charco
Don't forget that not all compounds can be used to make a standard solution. The solute must have certain characteristics to be considered for a primary standard solution:

1. It must be available in a highly pure form (Analar, for example)
2. It must be stable in the environment (not hygroscopic, deliquescent or efflorescent) and aqueous solution.
3. It should have a relatively high molar mass (preferably)
4. It must react quantitatively with the required compounds.
5. It must be soluble (yes, obvious, I know)

Seconday standards must themselves be determined using primary standard solutions before use.

thank u so much x
Original post by Pigster
You know the mass of the solute. You know the Mr of the solute. Therefore you know the amount.

You know the volume of the solution. Therefore you know the concentration.

The solution in the volumetric flask IS the standard solution.

thanks a lot xx

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