8.3 Strong and Weak Acids and Bases

welcome to subtopic 8.3 strong and weak

acids and bases so what does it mean to

say that an acid or base is strong let's

consider a prototypical strong acid

hydrochloric acid if we put hydrochloric

acid in water it dissociates into a

proton and the chloride ion because it

dissociates completely we say it's a

strong acid

what about sodium hydroxide if we put

sodium hydroxide in water it also

dissociates completely so we call sodium

hydroxide a strong base if we put

ammonia in water it dissociates only a

little bit therefore we say that ammonia

is a weak base there are only a few

strong acids and strong bases for IB

chemistry you specifically need to

remember hydrochloric nitric and

sulfuric acids you should also be

familiar with hydraulic hydrobromic

perchloric and chloric acids as most

chemists also consider those to be

strong acids as for strong bases all the

Group 1 and group 2 hydroxides are

considered to be strong though I'd be

chemistry syllabus only specifically

mentions the group 1 hydroxides and

barium hydroxide if it isn't on the

short list of strong acids or strong

bases that you just learned then you

should consider an acid or base to be

weak that said we still need to know a

few examples for the IB acetic or a thin

oeq acid is considered to be a weak acid

as are almost all other organic acids

carbonic and phosphoric acid are other

examples of weak acids we've already

learned that ammonia is a weak base and

so is ethyl amine which is an organic

base that has an amine group in fact all

bases that include an amine group are

considered to be weak bases there are

three ways to distinguish strong and

weak acids and bases electric

conductivity reaction rate and pH we've

already learned in topic 4 that anything

that dissociates into ions and water

will conduct electricity

well acids and bases by definition do

dissociate in water if they conduct

electricity very well then that's

sign that it's a strong acid or base if

they conduct electricity only mildly

then it's a weak acid or base strong

acids and strong bases not only

dissociate more ie

push their equal far to the right they

also react faster than a weak acid or a

weak base

finally the pH scale can of course tell

us if something is a strong or weak acid

if we put a strong acid in water we'll

measure a low pH value closer to the

zero side if we put a strong base in

water we'll measure a high pH value

closer to 14 weak acids and weak bases

will measure out closer to the middle

that's it thank you for watching