Stronger acid

[alez]

Is H2SO4 or HCl stronger?

 

[tommykins]

h2so4.

 

[alez]

Why?

 

[tommykins]

diprotic.

 

[alez]

k. thanks

 

[minijumbuk]

No, he's wrong. HCl is stronger.
The first ionisation of H2SO4 is strong, and the 2nd is weak.

HCl has only got 1 ionisation, and it is strong, so overall HCl is stronger.

But in the same conc. and volume of acids, H2SO4 would have more H+ ions.


I doubt they'd give you a question on this. But when they give you calculation questions involving H2SO4, assume both ionisations are strong.

 

[tommykins]

No, he's wrong. HCl is stronger.
The first ionisation of H2SO4 is strong, and the 2nd is weak.

HCl has only got 1 ionisation, and it is strong, so overall HCl is stronger.

But in the same conc. and volume of acids, H2SO4 would have more H+ ions.


I doubt they'd give you a question on this. But when they give you calculation questions involving H2SO4, assume both ionisations are strong.

Googled it, alot of different sources saying different things, but I'd still opt my answer to be correct.

 

[melonkitten]

nah date rape is better.

 

[alez]

so its HCl?
and I did get a question asking which one was stronger, from the creelman book
fuck

 

[appletooth]

My guess is that H2SO4 and HCl are equal in strength... They're both strong acids and neither is 'stronger' than the other, according to what 'strength' is defined as in the syllabus (although I agree that H2SO4 would have a lower pH when both are present in equal concentrations).

Since strength refers to the degree of ionisation of the acid, and H2SO4 and HCl ionise completely, then how can you say that one ionises to a greater extent than another? Both occur to 100%.

It's true that the second ionisation of H2SO4 doesn't proceed to completion, but isn't this because the hydrogen sulfate ion is weak? (i.e. referring to the strength of HSO4– as an acid.)

 

[minijumbuk]

so its HCl?
and I did get a question asking which one was stronger, from the creelman book
fuck

Creelman should have answers. What'd it say?

 

[what else?]

H2SO4 is stronger

 

[minijumbuk]

http://en.wikipedia.org/wiki/Strong_acid

A strong acid is an acid that ionizes completely in an aqueous solution (not in the case of sulfuric acid as it is diprotic), or in other terms, with a pKa < −1.74.

Some common strong acids (as ionizers)

(Strongest to the weakest)

* Perchloric acid HClO4
* Hydroiodic acid HI
* Hydrobromic acid HBr
* Hydrochloric acid HCl
* Sulfuric acid H2SO4 (Ka1/first dissociation only)
* Nitric acid HNO3
* Hydronium ion H3O+ or H+. For purposes of simplicity, H3O+ is often replaced in a chemical equation with H+. However, it should be noted that a bare proton simply does not exist in water but instead is bound to one of the lone pairs of electrons on the H2O molecule. This creates the hydronium ion and gives its single O atom a formal charge of +1.

* Some chemists include chloric acid (HClO3), bromic acid (HBrO3), perbromic acid (HBrO4), iodic acid (HIO3), and periodic acid (HIO4) as strong acids, although these are not universally accepted.

 

[Undermyskin]

If the explanation it provides is valid, wiki's answer makes perfect sense to me.

 

[syriangabsta]

http://en.wikipedia.org/wiki/Strong_acid

wow ownage. id still like to know what the answer in the textbook was @@

 

[alez]

we just got photocopies, not the answers
bullshit chem teacher who has no idea what shes ever talking about
im so fucked for chem

 

[samwell]

No, he's wrong. HCl is stronger.
The first ionisation of H2SO4 is strong, and the 2nd is weak.

HCl has only got 1 ionisation, and it is strong, so overall HCl is stronger.

But in the same conc. and volume of acids, H2SO4 would have more H+ ions.


I doubt they'd give you a question on this. But when they give you calculation questions involving H2SO4, assume both ionisations are strong.

ua answer is very right this is because if u consider brownted an lowry acid base theory that stronger acids would be more like to produce very weak conjugate bases that wouldnt undergo further reaction i.e: HCl+H2O-->Cl- +H3O+ while H2SO4 is diprotic thus: H2SO4 + H20---> H30+ +HSO4- but its conjugates base becomes amphroprotic showing that it then act as either a base or an acid on the next stage therefore showing that H2SO4 is weaker than HCl since its conjugate is a bit stronger.

 

[alez]

So is it HCl? this is so confusing me
ok question 22b in the 2002 HSC, HCl and H2SO4 both with a conc of 0.01mol/L
compare the pH of the two and justify.
The answer is no help, it says that H2SO4 has the lower pH because H2SO4 has a higher [H+], and is diprotic so a second [H+] can break away
but dont they have the same [H+]?
can someone please explain this cause I am so lost...

 

[Lucid Scintilla]

ua answer is very right this is because if u consider brownted an lowry acid base theory that stronger acids would be more like to produce very weak conjugate bases that wouldnt undergo further reaction i.e: HCl+H2O-->Cl- +H3O+ while H2SO4 is diprotic thus: H2SO4 + H20---> H30+ +HSO4- but its conjugates base becomes amphroprotic showing that it then act as either a base or an acid on the next stage therefore showing that H2SO4 is weaker than HCl since its conjugate is a bit stronger.

WTF? You might be right, or wrong; but it'd be super great if you didn't violate the English language while you're at it.

So is it HCl? this is so confusing me

Both are strong acids. True.

However, given equivalent concentrations and volumes, sulphuric acid would have more hydronium ions, and thus, can be said to be stronger.

ok question 22b in the 2002 HSC, HCl and H2SO4 both with a conc of 0.01mol/L
compare the pH of the two and justify.
The answer is no help, it says that H2SO4 has the lower pH because H2SO4 has a higher [H+], and is diprotic so a second [H+] can break away
but dont they have the same [H+]?

No.
From the first ionisation (of sulphuric acid; and the first and only of hydrochloric acid), you have equal numbers of hydronium/hydrogen ions in solution.
Sulphuric, being diprotic, will have a secondary ionisation, and will react with water to release another hydrogen.
Few, though; it's a weak ionisation, meaning the equilibrium for the bisulphate ion and water reaction will favour the reactant-side.

Higher conc. of H⁺ = lower pH.

 

[miz2nv]

need help 4 chem we hve 2 make a model showing
hydrochloric acid and acetic acid any help with how they will look

please help