Solubility Product Constant Video Lecture - Physical Chemistry for NEET

I don't always do videos about theory
but when I do it's because it's
important so listen up I want to tell
you about KSP the solubility product
constant and what in the world it
actually is what I want to point out is
that when you're dissolving pbi to solid
in water what's actually happening
you're taking that solid PB i2 and it's
dissolving into its ions you're going to
get a lead ion and the charge on it was
plus 2 it's now dissolved so we're going
to say aq as well
aqueous and you're going to get 2 iodide
ions iodine likes to have a charge of
minus 1 and because it's dissolved it
also gets little AQ when p bi 2
dissolves it makes a let ion and 2
iodides piece of cake what is the KSP
and how does it relate to this though
what I want to ask you is write the
equilibrium expression for this reaction
what is k eq well you take products over
reactants and you use concentrations you
ignore solids and liquids remember that
so products over reactants PB 2 + ^ 1
because there's no coefficient front in
front of that times the concentration of
I minus squared because there's a 2 in
front there / the concentrate Oh note we
don't include this because it's a solid
and solids are not included in the
equilibrium expression now for all
reactions where you're dissolving a
solid you're always going to ignore the
solid so it's always just the product of
the concentrations of the ions you form
including any relevant powers this is
special because it's the equilibrium
expression for something dissolving and
that's why rather than keq we call it k
SP because it's special or more
accurately because it's the solubility
of the particular chemical these
concentrations are related to how much
you can actually dissolve in it if you
put more than this
inside a solution equilibrium is going
to shift this way and you'll form solid
if you put some of this in solution you
may shift to the right
you know the shitali as principal this
is just a regular equilibrium and the
deal is that KSP represents the point at
which the two are in balance the point
at which you can't dissolve any more PB
i2 and you can't form any more ions in
solution check out one of my other
videos for how you can get the actual
concentration you're allowed to dissolve
from KSP of four now all I need you to
remember is that KSP is just a regular k
eq for something dissolving best of luck