today I'm going to introduce oxidation
reduction reactions or better known as
redox and redox reactions are where
electrons move or transfer from one
element to another and these are very
common reactions rusting as redox your
body is redox in right now so is my and
but what we can look at it we're going
to look at some metals and how they
react I have some magnesium metal here
little little chunks of magnesium metal
I'm not going to put a whole lot in
there and to it I'm going to add
hydrochloric acid this is known as
muriatic acid in a hardware store this
is six molar and when I add this you're
going to see fizzing bubbles steam is
getting very hot we definitely have a
reaction going on so what's the reaction
the reaction is magnesium solid is
giving its electrons to the HCL to make
magnesium ion and hydrogen gas
okay so the magnesium here is going to
give up two electrons
and each hydrogen is going to gain one
electron but we have two hydrogen so the
electrons lost that transfer to the gain
is the same that's always the case
and many metals that you can see we no
longer have any solid in this flask why
magnesium chloride is a soluble salt
another common material in a sink if
you've ever heard of galvanized pipe or
galvanized nail that means it's coated
with zinc and again we can put a little
bit of a zinc in this flask and we can
add hydrochloric acid to it and again
you can see bubbling not quite as
vigorous as the magnesium but definitely
bubbling for sure and it's producing
hydrogen gas as well and it's getting
warm and basically the same reaction is
happening okay instead of the magnesium
though I've got zinc here so the zinc is
and the zinc will slowly dissolve it's
going to take longer because the
reaction is not as fast all right
so many metals react when acid in fact
only some metals are somewhat acid
resistant they didn't tend to be very
expensive like gold or platinum they are
resistant to normal acid attack
last but not least though we can
actually have other reactions occur that
a redox again I am going to take some
zinc solid and in this case I'm going to
add copper sulfate now copper sulfate is
very blue
and in copper sulfate we have the copper
two plus ion which causes the blue color
okay so that's always a good
identification if it's really blue like
this and it has copper in it it probably
is a copper 2 plus ion so now I'm going
to add the copper to this st. and swirl
and a little more zing
and you may see I'll bring it a little
closer to the camera what we'll see is
happening here is we can see that the
solution is almost colorless the copper
the blue copper solution has gone away
and if you look closely that zinc is no
longer shiny silver but it's kind of got
a little brown on it see that look at
that liquid almost no blue that tells us
the copper ion is no longer there and
that brownish coating on the zinc that's
no longer silvery is actually copper
solid so what's happened is
two electrons have moved from the same
to the copper now in all these reactions
the atoms or ions actually hit they have
to touch and when they touch electrons
move from one to the other why does this
happen
this is nature it's energetically
favorable it's just like a ball rolling
down a hill okay
the electron quote-unquote sees a
different place to go it's lower in
energy so it goes there so these are
three examples of oxidation reduction
reactions
