Question

If you have H20 which is Amphoteric in solution and 2 salts NaSO4 and NH4F. Is there any way to reason out whether the solution will end up as acidic or basic?

Answer 1

My reasoning was that because NaSO4 is derived from the combination of a strong acid with a strong base the resulting salt will be neutral. This leaves only the NH4 and F with H20 to determine the direction of the reaction.

Answer 2

I figured the F- would create HF and OH- forcing the NH4 to give up its proton...but I am not sure that that is correct.

Answer 3

i don't think so it will form HF,

Answer 4

I thought there was some way to tell from the relative strength of the salt conjugates ...

Answer 5

yaaa its usaully done by that
but change in the Ph of water due to hydrolysis will be very low of +or -1

Answer 6

also, would the pH of the solution depend on the concentration of each of the salts?

Answer 7

Thanks I'm kind of beating a dead horse and my brain is fried at this point....I answered a question incorrectly on an exam...I said that with the NaSO4 and NH4F the product would be NH3 and H20.

Answer 8

but I think I was just confused or possibly conflating something that I had learned elsewhere with what the class that I am currently in is teaching.

Answer 9

am I correct that it will form NaF and NH4SO4?

Answer 10

well I didn't think the NaSO4 being the product of NaOH and H2SO4 a strong acid and strong base would do much of anything in a aqueous solution.

Answer 11

which I should be putting Na2SO4 I guess. But the NH4F is the product of NH3 and HF and because they are derived from weak acids and bases they can be acidic basic or neutral when in an aqueous solution.

Answer 12

...or rather they can produce acidic basic or neutral solutions (sorry im tired I am probably not making sense any more)

Answer 13

it seems to me like it all depends on the concentrations.

Answer 14

I was thinking that the concentration would not affect whether the resulting solution is acidic or basic but it may affect the degree of the acidity...I think...if the Na2SO4 is neutral you could add as much salt as you want to the solution and the solution would remain neutral....as for the NH4F they will act as a weak base and weak acid and they will be neutral if the disassociation constant is perfectly balanced If not balanced then the solution will be either acidic or basic right....

Answer 15

Its nearly 1 am thanks for the help guys im going to call it a night :)

Answer 16

from http://www.files.chem.vt.edu/chem-ed/courses/equil/salts/intro.html I saw that the Na2SO4 does change the pH of the solution at all

Answer 17

also from that site, I quote
"The tricky problems are the salts that contain both an acidic cation and a basic anion. In these cases, the solution will be acidic if Ka (of the cation) > Kb (of the anion) and basic if Kb > Ka."
the NH4F contains both an acidic cation and a basic anion

Answer 18

Oh nice thanks that site is very helpful.

Answer 19

Adding NH4F to water.
NH4+ is acidic and F- is basic. The Ka of NH4+ is 5.6x10-10 and Kb of F- is 1.4x10-11. Ka > Kb so the solution will be acidic

Answer 20

glad I could help

Answer 21

I appreciate it :)

Answer 22

what chemistry class is that from?

Answer 23

1st year chem

Answer 24

in college?

Answer 25

yes

Answer 26

u better use Philip Mathew book on advanced chemistry high fundamental book i ever used in my life!!

Answer 27

I wish I could give you a medal but I passed it out earlier sorry :(

Answer 28

it's fine, medals aren't important.

Answer 29

well I hope to see you around on here again thanks again for the help....I really do need to get to bed though :) night!