Titrations - Determing Strong/Weak Acids/Bases (1 Viewer)

[rokkuran-x]

Can someone help me to understand both:
- how to determine a strong or weak acid or base
- which indicator to use in a titration

much appreciated

 

[joben]

strong acid + strong base gives neutral solution
strong acid + weak base gives an acidic solution
weak acid + strong base gives basic solution
weak acid + weak base gives neutral solution.
These are just generalisations, but they generally work. To know which indicator, you have to know the pH range of where it changes colour (the indicator).

 

[dongerluo]

Strong acids are:
HCl, H2SO4, HNO3
Any acids other than those are Weak acid
H3PO4 is said to be triprotic although it is Weak acid

Indicator:
Stong acid + Stong base <---Use bromothymol blue
Stong acid + Weak base <---Use methyl orange
Weak acid + Stong base <---Use phenolphthalein

 

[dongerluo]

Ok..i found my notes on Stong/Weak acid or base

Common Stong acids:
hydrocholoric acid
sulfuric acid
nitric acid

Weak acids (decreasing order of acid strength) :
oxalic acid
hydrogensulfate ion
phosphoric acid
hydrofluoric acid
ethanoic acid
carbonic acid
hydrogen sulfide
dihydrogenphosphate ion
hypochlorous acid ( HClO )
ammonium ion
hydrocyanic acid ( HCN )

Strong bases:
sodium hydroxide
potassium hydroxide
barium hydroxide
magnesium hydroxide
calcium hydroxide

Weak bases:
ammonia