[danielle21_711]

Err yes, dibasic is how many h+ ions released. Keep it simply Do: Metal + Acid -> Salt + Hydrogen. a dibasic acid will produce twice as much h2 as a monobasic                 

but how would you actually measure the amount of gas? what apparatus would you need?

[Borek]

http://www.practicalchemistry.org/standard-techniques/generating-collecting-and-testing-gases,52,AR.html

[hatter]

hey, im doing the same thing for my exercise.

ive got the titration done easily as well as all the calculations for it, same with the gas exchange, but the problem i am having is proving it is dibasic with a gas exchange, i know i have to react MgCO3 with HCl and H2SO4 and im fine with the H2SO4 bit. but why HCl, and what is the reaction?

i know it should take double the amount of HCl to neutralise but, why? or is this going to far, and to indepth.

anyone want to help me out.

[Hunibunch]

how should i decide on the volumes or quatities of reactants to use, and how can i use calculations to prove why i chose them?!

[hatter]

hunibunch - calculations and reactants and masses for which experient?

[Lil-lindz]

hey, im doing the same thing for my exercise.

ive got the titration done easily as well as all the calculations for it, same with the gas exchange, but the problem i am having is proving it is dibasic with a gas exchange, i know i have to react MgCO3 with HCl and H2SO4 and im fine with the H2SO4 bit. but why HCl, and what is the reaction?

i know it should take double the amount of HCl to neutralise but, why? or is this going to far, and to indepth.

anyone want to help me out.

dont make it too complicated use Mg instead of MgCO3
the equations will be as follows:
2HCl + Mg = MgCl2 + H2
H2SO4 + Mg = MgSO4 + H2

what you should find is H2SO4 releases twice as much gas as HCl
For calculations just work out values for one mole of each acid and prove H2SO4 is double.

You use HCl because HCl is a monobasic acid (it gives off one H+ ion) and you can compare it to a dibasic acid to show the difference between the two

hope that makes sense

[just_smile_more]

I've got this as my chemistry AS plan as well  I know what I'm doing for the titration and the only thing I'm confused about is why the metal needs to be in excess for the gas collection experiment?  I thought the acid would have to be in excess so all the metal reacted and the most hydrogen was produced

Can anyone explain this for me please?

[Arkcon]

I've got this as my chemistry AS plan as well  I know what I'm doing for the titration and the only thing I'm confused about is why the metal needs to be in excess for the gas collection experiment?  I thought the acid would have to be in excess so all the metal reacted and the most hydrogen was produced

Can anyone explain this for me please?

Which reactant is in question?  And which product will you be quantifying, and why?  Try to figure it out again, along those lines, and see if it becomes clearer.

[Lil-lindz]

I've got this as my chemistry AS plan as well  I know what I'm doing for the titration and the only thing I'm confused about is why the metal needs to be in excess for the gas collection experiment?  I thought the acid would have to be in excess so all the metal reacted and the most hydrogen was produced

Can anyone explain this for me please?

you need all the acid to react so you can compare the amount of gas given off for each acid, if it was the other way round you would find out gas given off for a certain amount of metal, or at least that is my understanding

[danielle21_711]

for the gas collection, do you have to use two different acids?

Couldn't you just use one acid (sulphuric) and then just use mole calculations to work out the number of moles and everything? Or do you have to use two different to compare them?

thanks

[*Wardzy*]

hey, these replies help with the gas collection but not so much the titration... what exactly do you do for the titration?

[Arkcon]

Can I ask the more recent posters in this thread, to please read the original question, and the earlier responses, and then, maybe, consider asking their own new question, as a new topic, if it's very different from the original?

[danielle21_711]

Yeah, I have read the more recent posts. And my question is very relevant to the actual coursework, but I really don't think you need to compare two different acids, I think it's just creating extra work for yourself.

I've got another question as well, you need the metal to be in excess yeah? but how do you work out how much will be excess? I don't understand.

[HDW]

Am I right in thinking that sulphuric acid requires double the amount of NaOH or is it half, compared to HCl?

[Bolted]

Am I right in thinking that sulphuric acid requires double the amount of NaOH or is it half, compared to HCl?

Hello mate, i believe that the H2SO4 will produce double the amount of H2, than the HCL.

So, in effect to produce the same amount of H2, double the amount of HCL should be used.


Now for my own questions.

Now I think I know what to do for the gas collecting experiment, however I'm still having a few problems with the titration.

The whole point in titrations was to produce the concentration of the liquids used, to the best of my knowledge.

The only useful thing titrations would do in this context would be:

-This is a guess-

That double the amount of HCL would be needed as H2SO4 to neutralise the NAOH (maybe? - Please verify this chemical for this technqiue) as the HCL would need.

Now my problem comes when I think to myself:

In both my reactions, I am comparing two different chemicals, is it not possible to proove the H2SO4 is dibasic by just using calculations - especially in the titration.

Any help would be appreciated.
Thanks.