in this video I want to go over the term
soluble and insoluble salts
first of all what does soluble and insoluble mean next
the term salt so whenever we're referring to a salt
we're talking about an ionic compound, an ionic compound
forms when a cation a positively charged ion
and an anion which is a negatively charged ion
come together and form a bond, this forms an ionic compound now your cations are
going to be your metals
metals are located on the left side of the periodic table your anions
make up your nonmetals which are located on the right side of the periodic table
so a soluble salt
is simply an ionic compound that will dissolve
in a solvent such as water, an insoluble salt
is the complete opposite this is an ionic compound, once again you've got your
positive and your negative ions
but this compound will not dissolve in
water and only
a salt that contains a soluble cation or a soluble anion
would dissolve in water how do we determine
if a compound is soluble or if its insoluble
we use these solubility rules
from our solubility chart in order to determine whether something is soluble or
insoluble in water
what you see here is in this first column
we have our soluble salts so
all elements from group 1 or alkali metals
plus your ammonium ion compounds
are soluble you'll see nitrates are also soluble
acetates are soluble with
certain exceptions that being bound to silver ion
chlorides are soluble bromides and iodides
with exceptions of silver, lead,
copper and mercury, and then finally sulfates are soluble
with the exception of silver, lead, barium, strontium and calcium
on the right side of the table we have our insoluble
salts so our carbonates are insoluble
except when bound to your alkali metals or ammonium ions
sulfites are insoluble
phosphates, hydroxides
oxides and sulfides are insoluble
with certain exceptions now how do we use
the solubility chart to determine if a salt
is soluble or insoluble let's look at four examples here
to help us determine if these salts are soluble or insoluble
first one being sodium sulfate, is sodium sulfate soluble in water or not
in order to determine if sodium sulfate is soluble
we go back to our solubility chart what you will see here
is that it tells us sulfates are soluble
except when bound to silver, lead, barium, strontium
or calcium so therefore our compound sodium sulfate
should be soluble because it fits into our soluble column
so it is soluble because it contains that sodium
and that sulfate, the next compound magnesium carbonate
going back to our
solubility chart
magnesium carbonate made up of carbonate
here we find carbonate in our insoluble column
it's insoluble unless it's mixed with a group 1 alkali metal
an ammonium ion or an uranyl compound
magnesium is none of those, so therefore
magnesium carbonate would be insoluble let's look at the third
compound lead chloride
well our solubility chart tells us that
chlorides are soluble with certain exceptions however
the exceptions are silver, lead, copper
and mercury since lead is an exception
when lead chloride is bound together
that salt will be insoluble
and then finally our fourth example here we are magnesium chloride
magnesium chloride once again
being a chloride it should be soluble
because it does not fit into one of those exceptions
to that rule so magnesium chloride will be soluble
now how can we use these solubility rules to predict
the outcome whenever we mix two
ionic compounds together so here we have an example of an equation
we have we've got lead nitrate, lead nitrate
is soluble in water which is why we have this aq
following the lead nitrate means it's an aqueous compound
it is soluble in water we take lead nitrate we mix it with
sodium chloride also a soluble compound
so we mix these two compounds together we have two clear
colorless liquids both ionic compounds that are soluble salts
so they mix well in water, what do we expect to happen when we mix them
together we should be able to predict this
now before were able to predict this let's understand what happens
when we mix a soluble ionic salt
in water, whenever you have a salt that is soluble in water
for example sodium chloride you mix it in water
you do not have sodium chloride floating around in that water anymore
what happens is because of the charges on the water molecules
they will disassociate those ions from each other
so what you really have when you mix lead nitrate and sodium chloride
together
is you have a mixture a four separate ions flowing around
in your water solution you have lead ion
you have nitrate ion, sodium, and chlorine
ion these are all floating around
now that we can understand that we can get an idea of what we expect to happen
whenever we mix these two compounds together so what we have here
is we have two new combinations of ionic
compounds originally our lead and our nitrate were bound together
its soluble so when lead and nitrate
come together in the solution since it's soluble they will
come back apart however we also have lead
and sodium one thing you should notice though is the charge
lead and sodium both have positive charges
since they both have positive charges they will repel each other
whenever they come in close contact with each other however we also have lead
and chlorine, positive and a negative charge
whenever they come together this is a new combination of an
ionic salt so that's our first combination
is lead chloride our next
new compound is going to be sodium
positively charged sodium and negatively charged
nitrate or sodium nitrate so what we can do now as we can go back and look at our
solubility chart
and determine is lead chloride
soluble and is sodium nitrate
soluble what you remember from looking at your chart
is that
sodium nitrate is soluble
in water nitrates are soluble
especially when bound to sodium, chlorides
are soluble except for those four exceptions
copper, mercury, lead and silver
so when lead and chlorine come together
they form an insoluble salt so as soon as the lead
and a chloride ion come together and form that bond they form an
insoluble salt so they will precipitate out of solution
precipitate means to form a solid out of that liquid solution
falls to the bottom so we've now predicted
what we expect to happen whenever we mix these two compounds together
when we mix lead nitrate and sodium chloride together we get a solid form
of lead chloride, plus we get sodium
nitrate which is aqueous
or a soluble salt this is known as our
full equation our full equation shows
our new combinations of ions and whether there aqueous
or whether they're solids once they're formed
our ionic equation shows what we see at the molecular level happening
inside of that solution so instead of having lead nitrate and sodium chloride
we have each ion in its separate
um separate conditions however
whenever they're mixed together when lead chloride comes together
forms an insoluble salt so it does not come back apart
so it stays a solid and we're left over with our
sodium and our nitrate ions
and then finally we have our net ionic equation
our net ionic equation just gets rid of the
ions that don't play a part in the reaction these are known as spectator
ions
spectator ions in this case would be nitrate
and sodium you see that nitrate and sodium
are the same on both sides of the reactions if you have an ion that's the
same on the left and the right side
that a spectator ion get rid of the spectator ions
in your net ionic equation to simply show we'll mix
lead ion and chloride ion together we get a
solid insoluble ionic salt called lead chloride