Titration... why? (1 Viewer)

[Catspew]

we have a titration prac assessment coming up and i'm pretty sure we're going to be using Na2CO3 to make our primary standard. one problem: the goddam powder is impossible to dissolve... so we end up with the wrong answers.

our teacher doesn't care so does anyone around here have any tips on dissolving this crap?

any help is greatly appreciated

 

[karnage]

Have you tried using a stirring rod?

 

[Tiffanys]

that's weird, ours always dissolves, yeah stirring rod, distilled water... so wait, you actually perform the titration with visibly undissolved solid sodium carbonate still in the flask??

 

[Undermyskin]

Not really impossible. Maybe it is dissolved a bit but I can't observe. Theoretically it must be soluble. Errors can be because you use too much Na2CO3! When it reaches the saturation point, no more solid can be dissolved... I remember last year we had to measure the enthalpy change can there was something bloody solid and tool like ages until it 'disappeared' into water. Basically you need to be patient, I suppose. You can ask your teacher to have a look.

I don't think there's any problem with the reaction between acid with solid base. It can happen easily like HCl plus CaCO3. The point here is to minimize the errors plus to use any 'secondary standard' more easily without having to re-titrate again.

 

[Famguy]

Our Teacher gave us the standard, we only hjad to carry out the titration not make the standard solution. But when we did the prep for the prac we were able to dissolve it pretty easily.

 

[01]

Maybe you didn't hydrate the sodium carbonate properly. Therefore, it will take up some time for it to dissolve into your distilled water.

 

[midifile]

Yea i dont know why yours doesnt dissolve. It may take a while - make sure you keep stirring. Or maybe your school is gets cheap quality chemicals or it has been contaminated or someting. If it is a prac assesment and has a whole experimental write up then talk about this in your discussion. It is okay to have errors in your prac (if you have no control over them) as long as you mention them in the discussion and suggest ways to overcome this (ie geting better quality Na2CO3)

 

[xiao1985]

Use less Na2CO3 to make a more dilute solution?