[Lilly]

- Sorry but i had to delete my working out..

[Borek]

Does any one know how to set up the gas involving experiment for the chemistry planning exercise or where can i get more information on it?

30 seconds googling.

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

Also i am using the Mg metal to react against the dibasic acid H2SO4.

Mg + H2SO4 --> MgSO4 + H2 We are given 1.00moldm of sulphuric acid.

What quantity of solid Mg do i use? How do i work it out?

This is my attempt:

Mg + H2SO4 --> MgSO4 + H2

Ratio of Mg to H2SO4 is 1:1

If i work out the moles of H2SO4 first by using 25cm of volume and concentratio is already given (1.00moldm) and i get 0.025. through this formula                 Moles=volume x concentration

so the moles for Mg are same 0.025 since the ratio is 1:1

and if i put the 0.025 into the formula Mass=moles x molar mass.. This is 0.025 x 24.3 = 0.6075g   <---- Is this a correct way?

Perfect approach, just remember you should use a little bit more Mg - you want it to be in excess, to be sure all acid reacted.

[Lilly]

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[Borek]

Mg + H2SO4 --> MgSO4 + H2 <--- Is this 2 moles?

What is stoichiometric coefficient? 1 or 2?

A dibasic acid should give me 2 moles of H+ ions.

The ratio for H2 to H2SO4 is 1:1

Do the same calculations for 1 mol of HCl and compare amount of H₂ produced.

and i know that under typical laboratory conditions 1 mole of all gases occupy a molar volume of 24dm3 = 24000cm3

Not exactly. You should use PV=nRT, and to be really precise you should correct for water vapor pressure.

Ok i am confused..How do i work out how much H2 would be given out at the end? If it is too much and can not be measured-Is it ok to decrease by a scale factor?

Start with the volume you can meaure, than calculate amount of acid that should give this volume of gas, then calculate amount of Mg necessary.

[Lilly]

Do you know what goes into the flask first the Mg granuales or the sulphuric acid?

[merkl]

I would put the acid in first, then think up some way of adding the Mg without losing any gas given off when you put the bung on.

[Lilly]

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[Borek]

- I intend to produce 600cm3 of H2 gas thats 0.6 dm

Sounds reasonable, although details may depend on the equipment available.

Molar volume 24dm3

Please remember - this is only approximation!

0.6075g

Pretty good mass to start with

[Lilly]

How much does magnesium has to be in excess?

[Borek]

20% should do. You will see it was in excess - there should be visible piece of metal after the reaction.

[Lilly]

Thanx a million!

erm one last question.. for my titration experiment i decided to put the acid into the burette and NaOH in the conical flask. What indicator do i use for this? not sure but is it phenolphthalein? 

[spy derman]

has anyone finished their plan?