Why does HBr have lower pH than HNO3 if HNO3 is the stronger acid?

[omni]

which acid is more strong HNO3 or HBr?

i get the the pH for HNO3 is 5 and for HBr is 2 is it Possible if HNO3 is more strong acid so it must have the low pH than HBr yes?

thanks

 

[Borek]

pH of 0.01M HNO₃ is 2, and pH of 10^-5M HBr is 5 - as these number are exactly opposite to what you have listed, they obviously can't be used to compare acid strength.

What parameters of acids do you know?

 

[omni]

well 1x10^-5M for HNO3

and 1x10^-2 for HBr. but i think is it Possible Because HBr is a stronger acid than HNO3 yes?

thanks.

 

[Borek]

What defines acid strength? It is not pH, it is other parameter.

pH is not property of an acid, pH is a property of the solution.

 

[Point Conception]

Regarding other parameters of an acid: Besides HNO3 and H2SO4 causing low pH
in solution.Nitric acid is a very strong oxidizer and Sulphuric acid is a very strong
de-hydration acid.

 

[NEILS BOHR]

conc. also has to be considered...

 

[Borek]

Hint: anyone here ever heard about acid dissociation?

--

 

[omni]

i know that pka is What defines acid strength and also if the pH is more low so the acid is more strong no?

same for pka if it low so the acid is more strong truth?

thanks

 

[Point Conception]

Thats right the lower pKa the stronger the acid.
Also, Ka, the dissociation constant : (H⁺) (A^-) /(HA)
Is more valid for the weaker acids since the stronger mineral acids are so highly
dissociated that Ka is not measurable.

 

[omni]

ok thank you. :-)

 

[Borek]

i know that pka is What defines acid strength and also if the pH is more low so the acid is more strong no?

Yes and no. Yes - pKa defines acid strength. No - pH is irrelevant, as it is not a property of acid, but property of a solution. In some cases it is possible to compare strength of acids by comparing pH of solutions, but it requires careful design of the experiment. In the simplest case you need solutions to have the same concentration, but in many cases that is not enough.