strength of acids question

[byeh2004]

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circle the acid in each group which is the weakest acid of the group

1) H3PO4, KH2PO4, K2HPO4
2) Al3+, Cu2+, Na+, H+
3) H3pO4, H3PO3, HNO3, HClO4

thanks

 

[Freakedout]

k2hpo4
na+
h3po3

 

[ssa915]

k2hpo4
na+
h3po3

Shouldnt, for the second one, H+ be the weaker acid, since going down a group on the periodic table increases acidity (making Na+ the stronger acid)?

 

[estairella]

Shouldnt, for the second one, H+ be the weaker acid, since going down a group on the periodic table increases acidity (making Na+ the stronger acid)?

NaOH = strong base, Na+ = weak acid
H2O = weak base, H+ = weak acid

Now it should be easier to see that H+ is a stronger acid than Na+
H+ and OH- -> H2O (pretty favourable)
Na+ and OH- -> NaOH (doesn't happen, because a strong base, by defn. will dissociate 100% in water)

 

[ssa915]

NaOH = strong base, Na+ = weak acid
H2O = weak base, H+ = weak acid

Now it should be easier to see that H+ is a stronger acid than Na+
H+ and OH- -> H2O (pretty favourable)
Na+ and OH- -> NaOH (doesn't happen, because a strong base, by defn. will dissociate 100% in water)

I know strong acids/bases completely dissociate in water, but how did you get the above reactions? And what does that have to do with acdity? How would we use this rule to compare say, Ca and Ba?

 

[rcd]

I know strong acids/bases completely dissociate in water, but how did you get the above reactions? And what does that have to do with acdity? How would we use this rule to compare say, Ca and Ba?

Actually, trozman's explanation isn't exactly right.

I believe basicity increases with metalic character. Ba is more metalic than Ca, so it's more basic.

Br is less metallic than I, so it's more acidic.

 

[ssa915]

Actually, trozman's explanation isn't exactly right.

I believe basicity increases with metalic character. Ba is more metalic than Ca, so it's more basic.

Br is less metallic than I, so it's more acidic.

This is true for all elements on the periodic table, except when lookin at compounds, right? Like NaH and LiH?

 

[gridiron]

circle the acid in each group which is the weakest acid of the group

1) H3PO4, KH2PO4, K2HPO4
2) Al3+, Cu2+, Na+, H+
3) H3pO4, H3PO3, HNO3, HClO4

thanks

I think Q has made it pretty clear in the past---these questions belong in the study question Q & A thread.

 

[ssa915]

I think Q has made it pretty clear in the past---these questions belong in the study question Q & A thread.

thanks for your help

 

[gridiron]

thanks for your help

I wasn't trying to be an a** when I said that. What I intended for that to mean was that questions regarding material and concepts belong in the Study Question Q & A thread. Usually, when you post a question, you getter a faster and better reply throught that thread because the moderators help out.

 

[ssa915]

I wasn't trying to be an a** when I said that. What I intended for that to mean was that questions regarding material and concepts belong in the Study Question Q & A thread. Usually, when you post a question, you getter a faster and better reply throught that thread because the moderators help out.

Ok, thanks, i'll post the question in the Study Question Q and A. 🙂