5.1- Flashcards
what should u remember when doing buffer explanation qs?
write equilibrium equations to show the action of the buffer, eg H+ + OH- —>
what factors affect the ph of a buffer solution apparently?
Ka /pKa /acid strength/amount of dissociation,
temperature (but not “temperature & pressure”),
ratio/amounts/concentrations of weak acid and
conjugate base/salt
if the question says draw FORMULAE
DRAW MORE THAN 1
why is ph more convenient than h+?
[H+] deals with negative indices over a very wide range/
pH makes numbers manageable
/removes very small numbers
why would a certain indicator be appropriate?
pH range coincides with pH change during sharp rise
why is a burette suitable for a titration?
it can deliver variable volumes.
WHEN DRAWING COMPLEX IONS SHOULD U PUT IN THE CHARGES OF THE IONS BONDED TOGETHER
NO
Why would u add HCOONa to HCOOH to make a buffer?
It provides an excess of ethanoate ions to react with.
WHY USE A BURETTE IN A TITRATION?
IT CAN DELIVER VARIABLE VOLUMES.
when describing how a buffer works how should u word what happens when u add an acid?
equilibrium shifts to the left
h+ added reacts with the negative ion.
HOW DO U PREPARE A STANDARD SOLUTION (LITERALLY THE WORST)
Dissolve wanted mass of the solid in distilled water (less than the total volume u want) in a beaker
transfer the solution to a volumetric flask of the volume u want AND ensure that all solution is washed out of beaker (washings transferred to volumetric flask)
make solution up to 250 cm3 with distilled water AND ensure thorough mixing by inverting the flask several times.
IN AN IONIC COMPOUND REMEMBER WHAT ABOUT THE ORDER
THE POSITIVE ION IS ALWAYS WRITTEN FIRST.
if ur answer is,use a ph probe’ add…
on a data logger.
why are salts of a compound more soluble than the actual compound?
they’re ionic and attracted to polar h20.
how is something with an nh2 group able to react with acids?
the nitrogen has a lone electron pair which accepts a proton.
