Confused with this trial question (1 Viewer)

[get_back23]

question goes

HBr 0.15 mol/l pH 2
HBr 0.015 mol/l pH ?
HCl 0.15 mol/l pH 1.3
Hcl 0.015 mol/l pH 2.3


Predict the value of ?

What i did was because same conc of HBr has more pH thus less [H+] than HCl, then HBr is a acid that doesnt ionise completely
Then i estimate that a dilution factor of 10 would rise the pH by more than 1 because it is a weak acid.
but answer is 3
??
thanks for the help

 

[jeffwu95]

i think an dilution 10 times would cause a 10 times decrease in hydrogen ion concentration. This would cause an increase in pH by 1

 

[someth1ng]

Poor question, HBr and HCl are both strong acids and both ionise completely. The pH of HBr and HCl should be equal when concentrations are equal...

O well - answer is 3 though.

 

[karnbmx]

Poor question, HBr and HCl are both strong acids and both ionise completely. The pH of HBr and HCl should be equal when concentrations are equal...

O well - answer is 3 though.

For the HSC, we consider only the common laboratory acids (HCl, H2SO4, HNO3) as being "strong". The rest, unfortunately, are "weak". :I

 

[madharris]

For the HSC, we consider only the common laboratory acids (HCl, H2SO4, HNO3) as being "strong". The rest, unfortunately, are "weak". :I

I'm pretty sure Hbr and HF are considered strong acids for the hsc

 

[deswa1]

I'm pretty sure Hbr and HF are considered strong acids for the hsc

Yes this definitely.

 

[someth1ng]

I'm pretty sure that HF is not considered a strong acid.