Acid Strength Compared To Water

[MedPR]

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Is HClO a stronger or weaker acid than H3O+?

How would you know without looking up the pKa's?

 

[typicalindian]

I think it is H3O The reason being that H3O+ has a (+) charge so it more readily accepts electrons than hclo

 

[chiddler]

Is HClO a stronger or weaker acid than H3O+?

How would you know without looking up the pKa's?

much weaker.

H3O+ is a strong acid with pKa -1.7? -1.something anyway.

Besides having this memorized, here's how you can figure it out:

Comparing conjugate bases, you already know HClO is a weak acid so conjugate base is weak. But water. Water is an especially weak everything. pKa is 10^-14 of both ions. That is much weaker than HClO.

Meaning water is extremely stable relative to HClO.

So lets look at both for easy comparison. Before:
ClO(-)
H2O

Now we force a proton onto both

HClO
H3O+

Which one wants to give up its proton more?

 

[gettheleadout]

Comparing conjugate bases, you already know HClO is a weak acid so conjugate base is weak. But water. Water is an especially weak everything. pKa is 10^-14 of both ions. That is much weaker than HClO.

You mean the conjugate base is strong. But yes, I agree with comparing the conjugate bases of the two. Water is stable, and since HClO isn't a strong acid you know it's weak therefore the c.b. is relatively strong, so the compound with the weaker c.b. is the stronger acid: H3O+.

 

[chiddler]

You mean the conjugate base is strong. But yes, I agree with comparing the conjugate bases of the two. Water is stable, and since HClO isn't a strong acid you know it's weak therefore the c.b. is relatively strong, so the compound with the weaker c.b. is the stronger acid: H3O+.

weak acids make weak bases. it's only the super ridiculously weak acids that make strong bases. HClO doesn't fall in this category.

 

[gettheleadout]

weak acids make weak bases. it's only the super ridiculously weak acids that make strong bases. HClO doesn't fall in this category.

I don't mean literally "strong," just strong-er (i.e. the Kb for ClO- is greater than the Ka for HClO.)

 

[Arctangent]

H3O+ is one standard by which you categorize acids as strong or weak. "Strong acids" will are those that are stronger than H3O+, and "weak acids" are those weaker. I believe the pKa of H3O+ is around -1.7, so those stronger acids include HCl, HBr, HI, HClO4, H2SO4, and HBr. 2 more acids that are commonly called strong acids but are slightly weaker than H3O+ are HClO3 and HNO3. As HClO is not a strong acid by either of these categorizations, or by any I am aware of for the matter, HClO is weaker than H3O+.