This content explains how to represent chemical reactions in different formats, focusing on writing and balancing molecular, complete ionic, and net ionic equations, especially for reactions occurring in aqueous solutions.
hi class today we are learning about
writing and balancing Chemical Equations
our learning goals are to derive
chemical equations from narrative
descriptions of chemical reactions and
in this video we'll focus on writing and
balancing these equations in the total
ionic and net ionic formats
so in the previous video we learned
about writing chemical equations that
are balanced we talked about reactants
and products and what the arrow meant
and how we needed to balance them
there's some more information that we
can gather from chemical reactions that
we're going to talk about in this video
to start off with we'll learn that the
physical states of reactants and
products are usually indicated on a
chemical reaction and you'll find these
in parentheses following the the
molecules that they refer to so there
are going to be several different
descriptors right we might see a g in
parentheses to indicate that that
species is a gas we might have L for a
liquid s for something that's in the
solid form and then also AQ which stands
for aqueous so if we have a reactant
that is dissolved in water
so here we have an example showing the
reaction of solid sodium metal with
water to give sodium hydroxide this is a
base that is aqueous so that will be
dissolved in the water and also will
generate hydrogen gas
so this reaction is very specific and
that it's written for that particular
reaction that the sodium is a solid that
the water is liquid that the sodium
hydroxide is dissolved in the water and
that hydrogen gas is evolved
there are some other information we can
find on chemical reactions for example
there might be some sort of symbol or
writing that is indicated on top of the
arrow that separates the reactants and
products and in this example we see
carbon calcium carbonate decomposing to
calcium oxide and carbon dioxide and
you'll see this Delta symbol the
triangle that is above the arrow tells
us that heat is required in order for
the reaction to proceed
so that's just another example of some
information you might find written in
the chemical equation
for the rest of this video we're going
to focus on reactions in aqueous media
and in particular we're going to think
about how ionic species
will can be written in different formats
right so in this case we're going to
focus on the equation written here and
what we call the molecular format
you'll see that molecular equations
don't explicitly represent the ionic
species that are present in solution and
what that means is that ions are written
together so that the cation is with its respective
