just a few quick clear ups (1 Viewer)

[*sarah*]

hey,
ive just got a few things which are kind of annoying me and i was wondering if anyone could clarify for me

1)Explain the acidic/basic etc nature of salts
- i know why but ive seriously got 4 different explainations

2)Qualitatively and qualitatively describe titrations
-whats the difference again???

thanks heaps

 

[juggernaut]

you mean quantatively and qualitatively..

quantatively = only numbers
qualitatively = text (words)

 

[+:: $i[Q]u3 ::+]

for question 1, it's basically cuz salts are ionic substances, and made up of two ions (duh ^^) and those ions can either remain dissociated in water, OR they react with the water. Remember how some acids ionise totally but others only ionise partially? It's when you have an ion that can take up a H+ or OH- that makes up a weak acid/base that the pH of the soln can shift. and your four answers should be specific examples for acid/base; weak/strong pairings.

hope that helps

 

[CM_Tutor]

So, for example, NaCl is a neutral salt, as neither of its ions undergo hydrolysis (reaction with water), and thus pH is unaltered.

By contrast, ammonium chloride, NH₄Cl, is an acidic salt, as its cation undergoes hydrolysis:

NH₄⁺_(aq) + H₂O_(l) <---> NH_{3 (aq)} + H₃O⁺_(aq)

This hydrolysis produces hydronium ions, H₃O⁺, which lower the pH and make the solution acidic.

Finally, sodium acetate, NaCH₃CO₂, is a basic salt, as its anion undergoes hydrolysis:

CH₃CO₂^-_(aq) + H₂O_(l) <---> CH₃COOH<aub> (aq)</sub> + OH^-_(aq)

This hydrolysis produces hydroxide ions, OH^-, which raise the pH and make the solution basic.

 

[*sarah*]

ahh i get it now
thanks guys