Help! Chem Calulation Question (1 Viewer)

[queenie]

ok heres the question:

- a student placed a 0.5g strip of magnesium ribbon in 100 mL of:
i) o.1 mol/L ethanoic acid
ii) 0.1 mol/L sulfuric acid

Compare the chemistry of the above two reactions in terms of the strength of the acid, rate of reaction and volume of gas formed. Use equations in your answer.

equations:
ethanoic acid + magnesium --> magnesium ethanoate + hydrogen gas
2CH3C00H + Mg --> Mg(CH3C00)2 + H2


Ok, so for volume of gas formed, do i jus find n (m/molecular mass)
and since, no of moles of magnesium = no of moles of hydrogen gas, i then stick it in n=CV, where C = 0.1?

and so similarly for sulfuric acid....
H2S04 + Mg ---> MgS04 + H2


i don't understand how i'm supposed to answer the strength of the acid and rate of reaction part of the question (obviously a solution of sulfuric acid is stronger ie, has a lower pH, compared to a solution of ethanoic acid of the same concentration, as sulfuric acid ionises completly when mixed ith water... is that it?)

whats this rate of reaction busso?

 

[queenie]

any1....

clicker have a go at this one since u been to be posting so many quetions

 

[xiao1985]

lower the pH, faster the reaction... therefore H2SO4 will react more vigorously than ethanoic... however, same amount of H2 gas will be produced, given that there are excessive H+ ions in both solns...

 

[funking_you]

This is a REDOX reaction, example one, magnesium is oxidised, and hydrogen ions are reduced.

ethanoic acid is weak, that means it will not completely ionised, weak acids only really ionise 5%, hence only a small amount of hydrogen ions will be present in this reaction to cause the oxidation of the magnesium.

However with sulfuric acid, there is 0.1 M concentation of hydrogen ions, thats heaps! and hence the oxidation of magnesium will occur faster.

Make sense?

the more of the reactants there are, the faster the reaction (and easier) it will proceed.


the important thing here is to understand that this is NOT a neutralisation, its a redox reaction between hydrogen ions and the solid metal.
the acetate ion and sulfate ion are just spectator ions.


If you are still having troubles, i'll post a more clear and concise reply, just short on time now

Cheers,
George