[positiveion]

Predict and explain using equations where appropriate whether the following solutions are acidic alkaline or neutral

i. 0.1 mol dm^-3 FeCl3 (aq)

ii. 0.1 mol dm^-3 NaNO3 (aq)
iii. 0.1 mol dm^-3 Na2CO3 (aq)

help? i have NO idea how to approach this at all

in fact there are working solutions available

scanned and attached but i don't understand them :S

[Jzalkm]

I usually use this approach:
consider NH4Cl.
NH4+ is from NH3 (weak base)
Cl- is from HCl(strong acid)
therefore NH4Cl is weak acidic.(another reason which makes soil acidic)

NaCl: Na+ from NaOH (strong base), Cl- from HCl (strong acid);hence NaCl neutral

NaCH3COO: Na+ from NaOH (strong base), CH3COO- from CH3COOH (weak acid); hence weak base.

Another approach would be:
conjugate base of weak acid is weak base. similarly, conjugate acid of weak base is weak acid.
conjugate base of strong acid is considered neutral. similarly, conjugate acid of strong base considered neutral.
NH4+ is from NH3 so it is the conjugate acid of weak base and  is acidic.
Cl- from HCl and is the conjugate base of strong acid is neutral.
NH4+ acidic and Cl- being neutral would make NH4Cl acidic.