Titration Questions - Preparing Standard solution (1 Viewer)

[velox]

You know when u are preparing the primary solution, how do u know how many grams to put in the distilled water?

Thanks pplz

 

[LaCe]

U dont have to know how many grams to get a dissolved substance. All u have to do is accurately know the mass of the solid, the mass of the solution, (ie. volume)
You dont have to put an exact amount of the solid in the solution. U can dissolve i.e diluting it. And u use the ratio 1:10 for example. Put 10 grams in 100mL of water for example.

 

[xiao1985]

isn't knowing the mass of the solid knowing the grams of the solid?!

 

[Danni07]

Are you talking about finding out howmuch of a solid you must add to make a certain molarity?
you can use the formula number of moles = molarity x volume to find the number of moles, then substitue that number into the formula number of moles = mass/molar mass and manipulateit to find the mass you need.
Hope that made sense... PM me if it didn't

 

[Dreamerish*~]

You know when u are preparing the primary solution, how do u know how many grams to put in the distilled water?

Thanks pplz

it depends on the titration, doesn't it?
or is it usually 0.1m L^-1?

 

[velox]

Yes it does depend. All fixed up now. You work it out using n = cV with the information given. Then when you have the number of moles you multiply it by the molar mass.

That was what i needed to know

 

[Casmira]

Its a good idea not to put too much, I 2.65g is perfect imo, you end up with 0.025mol^-1 on a 250mL flask

 

[Aznpsycho]

It really depends on what sort of standard solution. They usually use 0.1M solutions used in titrations. For titrating acids, use anhydrous Sodium Carbonate. For titrating bases, use Oxalic acid. That should be in your textbooks.

Urgh, I have a titration assessment tomorrow. I really should get some sleep...

 

[wrong_turn]

what a coincidence..only problem is that we have had our assessment prac cancelled several times

 

[Jumbo Cactuar]

isn't knowing the mass of the solid knowing the grams of the solid?!

Pedants and purists are turning in their graves!

 

[xiao1985]

Pedants and purists are turning in their graves!

huh?! wut now?!

i didn't get that?!

 

[Jumbo Cactuar]

mass is quantity.
grams is unit of mass.

I have a professor who would go ballistic if anyone made that mistake!

 

[Emma-Jayde]

You know when u are preparing the primary solution, how do u know how many grams to put in the distilled water?

Thanks pplz

You need to know the mass of (eg) Na₂CO₃ that you put into your distilled water. The primary/standard solution doesn't need to be a certain concentration, you just need to know the concentration to do the rest of your calculations accurately.
I know mine ended up being 0.047molL^-1, it doesn't really matter.