- [Instructor] All right,
let's talk about water.
This is the first molecule
of many molecules we're going
to discuss as the next level
of biological understanding,
the next level of complexity.
Water has to be talked about
when talking about life,
because as I mentioned before,
all organisms are at minimum 70% water,
some is meant as 90% water,
which means the most abundant molecule
in any living organism and
therefore plays a key role
in the function of life.
When we look at other planets,
the first thing we look
for to determine whether we want
to investigate further for life is, water.
That's what scientists
look for on these planets
because that's how life
as we understand it,
that's life as we know.
So there are about seven
different properties
we're gonna go over
today, that play key roles
in the survival and function
of cells and organisms,
not just bacteria, but
us, living organisms
that are much more complex
with lots and lots of cells.
Water gets most of its
properties, not all but most,
because of hydrogen bonding.
And that's why that's a key concept,
though it is the weakest of
the three types of bonds,
it is crucial for the function
or properties of water,
especially its life giving properties.
One of the fascinating things about water
that you will not find in any
other substance like this,
I mean, there are others
that are kind of have some
similarities, but water,
what's so unique about water?
Well, if you take any other substance,
it does not necessarily have the range
that water has for remaining the liquid.
Being liquid is crucial for life
and from zero degrees Celsius
to 100 degrees Celsius,
no other molecule really
has that huge of a range
where it remains a liquid.
Now, why does it remain a liquid?
Well, it's due to the hydrogen bonding.
So what happens is the water molecules
are constantly moving around one another,
they have the flexibility
to keep breaking the hydrogen bonds.
But the hydrogen bonds
collectively are strong enough
to keep water with itself.
As such, it remains a
liquid unless you heat it up
so much that the molecules start escaping
or you cool it down so much
that they just start moving all together
and that's where you get gas versus solid.
All right.
So let's talk about the
first property of water
that's essential for all life.
Water is a good solvent.
Now if you haven't taken chemistry,
or if you haven't ever cleaned
out a paintbrush or whatnot,
a solvent is something that
dissolves other substances.
We know that paint thinner is really good
for dissolving paint.
A lot of time the paints
are non water based
and therefore need a
particular solvent to be able
to break them down.
Well, water is by far
one of the best solvents
because of the large array of
molecules that can dissolve.
And when we say dissolve, we
mean, interacts and mixes in.
When you have something like a fat,
and I've had this for about 10 years now,
and the fat and the water have
still never mixed together.
Why?
Because the fat is what we
call a hydrophobic substance.
Now why is it hydrophobic?
Hydro means water, phobic
means fearing or hating.
Lipids are what we call
nonpolar molecules.
They're very large, they
don't have any charge to them
so therefore, they don't like water.
They're not attracted to water
and so that doesn't dissolve in water.
So what types of molecules are
actually attracted to water?
We call them hydrophilic.
Hydro again meaning water,
philic means to like.
So here are some examples,
and I'm going to use
certain real life examples
to describe these, and
these are what you're gonna
be tested on.
I'm gonna give you
scenarios and you'll need
to tell me, oh, that's an example of water
being a good solvent.
All right, so let's first talk
about polar nonionic substances.
Remember, polar means that
there's unequal sharing
between the covalent bonds
and certain substances.
Well, one of the easiest
examples of this is sugar.
Sugar is a polar molecule and the reason
why it's absolutely essential
for water to be able
to dissolve sugars is
because since all organisms
are at least 70% water,
in order to be able
to get the nutrients
like sugars to the parts
of the cell where it needs that energy,
it needs to be able to mix in with water,
it can't separate itself from
water like fats typically do.
There are key ways in which we
can get fats into our cells,
but it's much more difficult
and our bodies are designed
to be able to handle fats to
be able to undergo metabolism,
but not all organisms necessarily can,
they pretty much just go
for sugars and whatnot
because of that polar substance.
Sugars are attracted to water
and therefore dissolve in water.
You drink sugar, gets into your stomach,
dissolves into your
blood, which is 55% water.
So your blood being 55% water,
easily dissolves these substances
and their cardiovascular system
redistributes it to the rest
of the cells in your body.
And those cells absorb
the glucose and sugars
and your body gets the energy it needs.
Okay, let's look at
ions, ions such as salt,
sodium, chloride, calcium
is an ions, potassium,
what are these ions necessary for?
Well, your muscles and your neurons
and the various cells in your body
absolutely need these ions to be able
to function properly;
calcium for your muscles,
sodium, potassium, calcium as
well, for your nervous system.
And if these ions didn't
dissolve in water,
then your cells wouldn't
be able to function.
Here's an example of why salt
dissolves so easily in water.
Remember, salt is two
ions, sodium and chloride.
Well, just like water is
attracted to itself due
to its polarity and therefore
creates hydrogen bonds,
by the same token, water is also attracted
to any other polar or
charged, meaning ions,
substance as such, when
the salt crystals get
in the water molecules
there are just trillions
of these water molecules
bombarding the salt,
breaking off the ions and
then surrounding them,
preventing the ions from
therefore interacting
with one another.
So the negative slight polarity
on the oxygen is attracted
to the positive sodium ion,
and the slight positive charge
on the hydrogen atoms are attracted
to the negative chloride ion.
As such, this is why salt will
not, unless you saturate it
to a high concentration,
the salt will not,
the sodium and chloride
will not come back together
to form these crystals.
Now, you can get that to do that,
but it requires a concentrations
of sodium chloride
so high that you really can't
get life existing in that.
So that's why we don't
really form ionic bonds
in any living organism.
Now, there are exceptions, obviously,
there's certain molecules
that will go over
but that's why solid is so easily broken
in water due to the polarity of water
and its ability to break all of these
into their individual ions
and therefore surround them,
prevent them from interacting.
Good solid.
Now one last example.
This is key too for you and I survival,
as well as other organisms.
It can even dissolve what
we call nonpolar gases.
Now normally, if a
molecule is not charged,
and if it's not polar and
therefore it doesn't have any type
of positive or negative,
it's usually hydrophobic.
However, if it's small enough,
then it doesn't matter.
We're talking about things
like oxygen, carbon dioxide,
nitrous oxide, your brain actually uses
that as a signaling chemical,
although it's also used as a laughing gas.
So, oxygen and carbon dioxide.
Those are two main ones
that I'm gonna look
at as an example.
Why is that critical?
Because if you could not dissolve oxygen
into your blood for your
hemoglobin in your blood cells
to pick up, then we'd be dead,
we wouldn't be able to undergo
the metabolism that we need.
As we break down sugars
and release carbon dioxide,
if it couldn't dissolve
in our blood and then get
to our lungs and breathe out, then, again,
we wouldn't be able to function, survive.
So, oxygen and carbon dioxide
though they are nonpolar,
they're small enough that
they will dissolve in water.
I mean, that's really how
you get carbonated soda.
Is high concentrations of carbon dioxide
dissolved into water.
Now, it doesn't stay as carbon dioxide,
it actually turns into
what we call carbonic acid.
That's why Coca-Cola and
some of these other things
have a very, very acidic environment,
and that will be the
end of today's lecture
when we talk about acids and bases.
All right.
Now let's talk about
cohesion and adhesion.
(clears throat)
Some of these examples are more applicable
to certain living organisms than others,
which is why I use the
examples that I use,
so not all of them are gonna be about us.
This is especially important for this one,
for cohesion and adhesion.
So let's look at what
cohesion and adhesion is
and then let's see how
that applies to life.
Cohesion is due to hydrogen bonding
where the water molecules
like to be with one another.
When we think of a cohesive group,
it's a group that works well together.
Well, if you've never tried this before,
try doing this with some
oil or with some alcohol
or whatnot, you won't get this.
Has to be relatively pure
water to have this happen.
What's happening here is
as you're adding water,
notice that it's not falling off the edge
and the reason for that,
and eventually it will,
but initially, it likes
to stay with the self
which is why water will
form these almost bubbles.
You'll see in a video today that I show
where the skin of an organism
is so water repellent
that it actually just forms
this nice little bubble
because of the organism skin.
So cohesion, what's it's application?
Well, due to the fact
that water is so cohesive,
there's a lot of energy
that's constantly bombarding
the water on our planet,
the sunlight and whatnot,
and normally, other substances,
think about alcohol,
other substances transition
from a liquid to a gas,
they really quickly.
But because water is so
cohesive that as the energy
is being absorbed, instead of the surface
of the water instantly evaporating,
it is held down by a lot
of the other water molecules
and actually requires
the whole mass to heat up
before water molecules are able
to start escaping.
Water doesn't evaporate as fast
as other substances
primarily because of that,
takes a substantial amount of energy
to transition and the more water you have,
the more energy you have to pump
into it for it to be able to do that.
So cohesion is one of
the reasons why we have
so much liquid water on this
planet amongst the many's,
but ponds and lakes and
other things don't evaporate
as quickly as we think that
they would necessarily work
because of cohesion.
All right, now adhesion,
when something adheres to
something else, what does it do?
- [Student] Sticks.
- [Instructor] It sticks, okay.
So water lights, other polar surfaces,
you can see with this glass pipette here,
the water is actually
crawling up the sides,
it's forming this little bubble meniscus,
whereas for crawling up the sides
because the glass itself
is polar, in fact,
an example of this, if
you've ever given blood,
or donated blood or whatever,
the nurse checks for your iron,
they prick your finger and then they take
this glass rod and they
just put it right up to it.
They don't have to suck on it,
they don't have to do anything
else but put it right to it.
Why?
'Cause the water in your
blood naturally adheres
to the polar surface and pulls itself up.
Now there's a limit to this as well.
If you have a really,
really long glass pipette,
then you might have to create some suction
because gravity starts
preventing the mass of water,
but that's the basic principle,
water likes other polar surfaces.
Okay, now how does this apply to life?
Well, on the left you see a tree.
One of the biggest issues that a tree has
to overcome is they don't
have a cardiovascular system
like you and I, they don't pump fluids
through their cells
actively, like you and I,
because of our heart, they're
heartless like that, trees.
So, ultimately, how do they get water up
from the roots all the way to the leaves
where they need it most?
They obviously need it
through the other aspects
of their trunk, but they
need it most in the leaves
and some of these trees can
be 200 or more feet tall.
It's a quite an endeavor
to pull it up from gravity.
Well, two principles applied
to this, cohesion and adhesion.
The first one, adhesion, is
that the roots will absorb
the water almost like a sponge.
That's why sponges typically work,
is because of their polar substances
that cause the water to be absorbed.
And the vascular system, yes,
trees do have a vascular
system just not cardiovascular,
the vascular system is like
having millions and millions
of these tiny capillaries.
The water just naturally draws itself up
because the vascular system
is charged, it's polar.
All right, well, one of
the reinforcing aspects
of this is, as the water gets pulled up,
water likes to be with itself.
So it reinforces that absorption
due to cohesion as well.
So this is one of those
where the answers would be,
if I give you this example of
the tree pulling up moisture
from its roots to the leaves,
it's both cohesion and adhesion.
There are other questions
which may test you separately,
such as the water evaporation
or the nurse pricking your
finger the capillary tube,
those are separate examples
of cohesion and adhesion
that you might get as well.
All right, now we get some
adhesion in our bloodstream
especially as the blood
flows up against gravity,
but most of it is due to the
pressure that our heart creates
to push the blood through our system.
But there is some adhesion going on there
in our cardiovascular system,
but it's minimal compared
to what our heart's actually
doing for the blood.
By the way, that's one of the reasons
why if you don't get
enough blood to your brain,
your body passes out, why?
'Cause it says throw yourself horizontally
so I don't have to work against gravity
and I get blood to your brain.
That's one of your default mechanisms is,
it'll make you pass out and
collapse so you go horizontal
instead of vertical.
So, that and it's not
getting enough oxygen
to be able to function.
So it shuts all the
non-essential systems down,
which is your cognition, and takes care
of you until you find can
be restored to homeostasis.
Water due to its attraction
to itself forms this skin or barrier.
Those of you who may be Boy Scouts
and created your own compass, I did.
I've never had any use for this knowledge,
but if you take a needle,
rub a magnet on it
and magnetize it temporarily
and then place it just right,
you can actually have it sit on top
of the water without
breaking that surface.
And the reason for that is
because water being attracted
to itself forms this barrier.
Now there's a couple of
organisms that can actually use
this to their advantage.
All right, and then here's
another example water flea
or whatnot, that they
sit on top of the water
without breaking the surface tension.
So what are some of it's applications?
Well, you saw several, the
gecko can use that surface
as another livable layer.
These water fleas typically
lay their eggs on top
of the water.
Debris, when it falls on top of the water
doesn't instantly sink,
that kinda gives another
ecological layer for fish
and other organisms to have their food
rather than having it sink
to the bottom and be inaccessible.
So there's a number of situations in where
this really becomes important,
especially since our planet's
covered with 2/3 water.
It's critical for the
ecosystems for these organisms
to have this extra
barrier where they're able
to do the things that they do.
This is one that is
definitely relevant to us
which is why, like I said,
you put your life in danger
when you exercise, because
what ends up happening
as you exercise is heat is generated
as a massive byproduct of metabolism.
Well, thankfully, we have
so much water in our cells
and circulating through our body,
that water has an immense,
what we call, heat capacity.
It's able to absorb tremendous amounts
of energy without
changing it's temperature
as much as other substances would.
Think about how long it
takes to boil a pot of water,
you have to constantly pump.
The bigger the pot of water,
the more you have to pump
energy into it to get it
to raise its temperature.
Now finally, it'll raise its
temperature to boiling point,
but even boiling point depends upon
the overall atmospheric pressure.
If you think that when you
boil water up here in Utah,
that it's 100 degrees
Celsius, you're wrong.
That's at sea level, more or less.
Up here where we're at
4000 feet or whatnot,
you might be able to get the water
to about 95 degrees Celsius,
and then it'll start boiling.
In fact, you can boil
water at room temperature,
all you have to do is remove
the atmosphere and it'll boil,
it has enough heat in it to actually turn
into a vapor as the atmospheric pressure
that really determines what
that over boiling point is.
If you've ever done pressure cooking,
why is that advantageous?
Because by increasing the
pressure, you can make it
so the water could be heated
up even more before it reach
that evaporation point,
that's really what pressure cooking is.
So, due to the fact that
water can absorb all
of this energy without
changing it's temperature,
is the reason why we don't put our lives
in danger when we exercise.
But, if we can't get rid
of that heat, then yes,
we do put our lives in danger
and that's where fever
from a viral infection,
if your body doesn't break a sweat,
which is what it usually stops
during the fever from doing,
that's why when you break the
sweat, you're like, oh, good,
the body is restoring
itself to homeostasis.
Because when we sweat,
that water which has all
of that heat is going to
the surface of our skin,
and then it is transitioning
to a vapor and pulling
that energy or that heat away from us,
thus cooling us down.
We've talked about this
before as far as homeostasis.
So that's why we can exercise
and not have any problems,
is because our body can handle that.
But it does require your ability to sweat.
In fact, if you go to some of
these tropical rainforests,
you can die from heatstroke
and heat exhaustion,
because even though you
sweat, the air is so moist,
100% humidity, that it
requires the moisture
to be able to evaporate.
If it can evaporate, you die.
I mean, if you've ever watched
the, what do they call it?
"Dual Survivors" or
"Bear Grylls" or whatnot,
you might have seen that
in one of the episodes
where they're like, we're gonna die
if we can't cool our body down
because the sweating does no good.
It requires evaporation
for your body to get rid
of that heat.
All right, but not to worry
about that here in Utah,
it is always freaking dry.
But, another application
is the fact that if water
was not able to absorb all of this energy,
we wouldn't have the
ecosystems around our planet
that we do.
What am I talking about?
Well, the equator is always pointing
towards the sun.
It's always getting sun day
in and day out and whatnot,
which is heating up the oceans,
and then the current
redistribute that energy.
Well, they essentially draw
tremendous amounts of energy
and then as they get
distributed to the Northern
and Southern Hemispheres, that is able
to allow other ecosystems
to remain stable,
they're able to get that energy.
'Cause what happens is, as it gets hotter,
the closer you are to a body of water,
the less temperature
fluctuations you're going to get
in that environment.
There are other factors as well,
but this is a major factor.
The closer you are to sunny
San Diego and his nice beaches,
the less huge temperature
fluctuations you get,
because as it gets colder,
the heat from the oceans
will warm the air up.
As it gets hotter, the heat
gets absorbed by the water.
So whatever the temperature
is relative to the water,
it'll either absorb it or
release it thus temporary,
many of these regions that are
near large bodies of water.
So, those are some of the applications
of water being having high heat capacity,
especially for us and
other organisms as well.
They follow the same guidelines in that,
there must be some type of
cooling system to be able
to allow for the water
to release its energy.
Now, this is a fascinating
one about water.
We know that most of our planet is water,
and there are many regions on our planet
that require it to be in its solid state.
Well, one of the issues you deal
with with all substances except for water
is that the solid state of any material
is usually more dense
than the liquid state,
which means that when you cause
something to become solid,
if you put it in itself self
as a liquid, it would sink.
Water is not like that.
I think there's only one
other substance like water
that can actually do this
and it's very rare,
it's not commonly found.
Why does water in its solid
state or what we call ice,
float in its liquid state?
This is an abnormality
when you think about all
of the molecules.
Well, here's what happens.
When water is in its liquid state,
the water molecules are free
to move around one another,
they have a certain amount of density.
Obviously, if you heat water up,
it becomes a little less
dense, if you cool it down,
it becomes a little more dense.
However, when you get close to freezing,
this is what starts happening
to the water molecules;
instead of getting closer
and closer together
and more dense, they actually push apart
from one another to create
these helixes that create space.
So in that manner,
water becomes less dense
in its solid state than it
does in this liquid state.
In fact, water is most dense,
this is more of a side note,
but water is most dense
at four degrees Celsius,
which is close, but after
four degrees Celsius,
when it starts going lower,
then water actually starts expanding.
Now there are other things
that can aid in this as well.
Like there are ways in which
you can have pure water
be really, really solid,
but there's gases,
there's always oxygen and carbon dioxide
that's usually mixed in as well,
that helps with the
overall buoyancy of it.
But ultimately, it comes down to this,
that water actually expands as it freezes.
Now, there's an issue with this,
fish and other organisms that
live in these environments,
if the water were allowed
to freeze in their cells,
then their cells would be destroyed, why?
This is where we get into
problems with cryogenics
or cryo freezing is as the water,
that's why we can't freeze
large living organisms
without destroying them
because as the water freezes
and it expands, think about what happens
when you put a coke can in the freezer,
it'll expand and actually cause the metal
to distort and sometimes
cause it to burst, right?
That's why you don't put pure water
in your radiators here in
Utah because if you did,
your radiator would burst.
We put what's called antifreeze
usually mixture 50, 50.
Well, guess what?
Fish make a natural antifreeze
so that they can live
in these environments
where normally their cells
might start forming these water crystals
because it's so freaking cold, but they,
with this antifreeze, lower
the freezing point of water.
And that's really what antifreeze
in your car's radiator
does is, it would have
to get down to like
lower than negative 20,
possibly even further
than that before you start
getting certain ice crystals forming.
So antifreeze, it's one of those things.
Now the biggest problem if we were to try
to do cryogenics, we can
do with smaller organisms
is you can put an antifreeze,
so to speak, in the cells,
but usually that's toxic to
the cells into the organism.
So it's a very complex
process, we're still trying
to work out the dynamics,
but usually any substance
you put in the cells
to prevent ice crystals
from forming and expanding,
will also kill the cells itself.
And then you have the additional benefit
of having another layer
for organisms to be able
to avoid their predators,
seal avoided a sea lion,
or polar bears being
able to get their food.
This is why there's
concern about the ice shelf
and whatnot to the habitat
of many of these organisms.
So that extra ice layer
forms another habitat
kind of like surface tension does
in its liquid state for other organisms.
All right, water doesn't
always stay together.
Due to the polar covalent
bond and its nature
between oxygen and
hydrogen, there are times
where the oxygen will steal
the electrons from hydrogen.
Now as we learned in the previous lecture,
when an atom steals
electrons, it becomes a what?
What when atom steals
electrons, has more electrons
and protons, what do we call that?
- [Students] Ion.
- [Instructor] We call
it an ion, like chloride.
When it steals electrons,
it becomes a negative ion.
What happens if it loses electrons?
Like hydrogen, it becomes a positive ion.
Now, these ions do not
follow the simple rules
that we discussed before,
most other ions do;
calcium, potassium, sodium, chloride,
those are stable ions.
When they steal electrons
or give up electrons,
they're just fine.
These ions on the other hand are unstable.
I'm gonna focus primarily on
this one right here, hydrogen.
Let's look at why it's unstable.
'Cause according to valence
electron shell theory,
atoms try to become stable by
losing or gaining electrons
or sharing electrons.
So why are these unstable?
Well, as I mentioned, hydrogen
is just a single proton,
that's it, just one proton.
So it doesn't have a
valence electron shell
to fill up if it loses its electron.
Well, according to valence
electron shell theory,
you need at least one shell.
That's why hydrogen is not stable,
is because when you lose that electron,
and it has no electrons,
it becomes a positively charged ion.
But, because it still
wants to become stable,
how many electrons does it
need in that first shell?
How many can fill up in the first shell?
- [Students] Two.
- [Instructor] Two, where's it going
to get those electrons from?
Anything it comes in contact with.
So a solution that has
a high concentration
of these hydrogen ions is called an acid.
This is why acids are so corrosive.
Because the stronger the acid,
the more these hydrogen
ions are fighting each other
to steal electrons from
anything they can get ahold of.
So we have acid in us, what do you think?
Where's our major source of acid?
- [Student] Stomach.
- [Instructor] In our stomach, why?
Because as we eat food, we
need to break them down further
so that we can absorb
them into our bloodstream
and into ourselves.
In fact, our stomach acid is probably one
of the most acidic environments
of almost any biological organism.
That's, I mean, it's amazing
that we don't chew ourselves up.
We do sometimes, we form
ourselves and other things
but those are more genetic issues.
We usually coat our stomach with a mucus
that prevents us from eating
ourselves, so to speak,
but if that mucus is
not produced properly,
and you have over too much acid,
you could start burning
holes in your stomach
and getting ulcers and whatnot.
So, water naturally undergoes this process
where not all of it
but a small percentage.
If we're talking trillions of
water molecules in an area,
we're talking a tiny fraction
of them will do this.
Now it can reform.
Hydrogen ions and hydroxide ions come back
together like oh, okay, I
forgive, you come back together
and they share the
electrons all over again.
But as one reforms, another one breaks up.
So there's always a small
portion, even in pure water,
which is not what comes
out of your tap by the way,
even in pure water, there's
always a small percentage
of the molecules that have broken up
into hydrogen ions and hydroxide ions.
Now, as long as the
proportion of hydrogen ions
and hydroxide ions is the same,
then we call it a neutral solution.
So anything, any body of water
that has the same concentration
of hydrogen hydroxide,
it's neutral.
However, if you put something into water
that increases the
hydrogen ion concentration,
we call that an acid.
On the opposite side, when
you put something in water
that causes the water to
have more hydroxide ions,
we call that a base, or
sometimes called alkaline.
You will get alkaline batteries,
they're based off of a base solution
rather than an acidic solution.
The battery in your
car is an acid battery,
but the battery that you
have put in your remotes
and other things like that,
those are usually alkaline batteries.
So alkaline and base pretty
much mean the same thing.
In fact, I use that interchangeably.
Most of the time I try
to use the word alkaline
on some questions, because
people have been confused
by the use of the word base
on one of my questions,
so I'll explain a little more later.
Okay, so what are some very,
very strong acids that exist?
Hydrochloric acid, let's
look at what happens
when you put that into water.
This is by far one of
the most volatile acids
that there is.
When you put hydrogen
and chloride into water,
what happens is the chloride
immediately steals the electron
from the hydrogen and hydrogen
is left all by itself.
Well, the chloride ion is stable.
We've talked about that
before, how this is stable,
it fills up this outermost
valence electron shell,
but it leaves behind a
very unstable hydrogen ion
that is just looking for
any molecules, anything
to interact with to get those
electrons to become stable.
So the more hydrogen ions
you pump into something,
the more acidic it is.
On the reverse side,
there are things which we call bases
that increase the hydroxide
ion concentration.
Now that can happen one of two ways,
you can either remove
hydrogen ions from that,
or you can just add
straight up hydroxide ions.
So let's look at adding hydroxide ions,
that's the easier one.
Sodium hydroxide.
Well, we know that sodium
to become stable loves
to give up that one electron,
so it gives it to this
oxygen and hydrogen.
Yes, ions can be molecules,
you can have molecules that are ions.
We didn't talk about it last time
and we're not going to really
make more mention of it,
but you can have molecules
that have an extra electron,
they're considered an ion.
For purposes I'm not gonna go into,
this molecule is also unstable,
so this is not a stable molecule,
just like hydrogen's
not a stable molecule.
Now, bases are a little
more slow acting than acids.
They disrupt cellular
mechanisms, but not as quickly
nor as violently as acids typically do.
What am I talking about?
Most of you deal with bases on a,
well, hopefully you deal
with it on a daily basis,
when you clean your house.
Most household cleaners are
bases, they're not acids, right?
You can work with acids, you
can use them like vinegar
is very acidic, but it's very noxious too.
My kids use that, that's
another story for another day,
to clean the mirror.
It does clean mirrors very good.
In fact, you can clean your toilet
with Coca-Cola very good as well,
'cause Coca Cola has a very acidic pH,
we'll talk about pH in a
sec, similar to vinegar.
Coca-Cola and vinegar have
about the same acidity to them.
So, sodium gets left behind, very stable,
doesn't interact with anything
but then the hydroxide ion will.
So how do we measure this?
We have what's called the pH scale
and you will need to know the scale.
You're not gonna have to calculate it,
the pH scale is actually
a mathematical formula
of calculating the
concentration of hydrogen ions
in a solution.
So you not just gonna have
to memorize the scale,
you're not gonna have to memorize
how to calculate things or
whatnot, that's for chemistry
that's for different class.
So what is the scale?
What ranges from zero to
seven to 14, so zero to 14,
but seven is a key number
because if a solution has a pH
of seven, then it's neutral.
The concentration, this what
that means, of hydrogen ions
is equal to the concentration
of hydroxide ions, okay?
So any solution that is,
like if you have pure water,
it would be neutral, it
would have a pH of seven,
because it has the equal amounts
of hydrogen and hydroxide ions.
Now, here's the confusing part,
as the hydrogen ion
concentration increases,
the pH drops down to zero.
And this is because the
mathematical formula
is a negative log, which means
that as the concentration
of hydrogen ion goes
up, the value goes down.
Don't worry, just again,
memorize the scale,
the closer to zero you get,
the more acidic the solution.
Guess what our stomach acid is about.
It's about one.
That's how caustic that solution
and that's why when you throw up,
it burns because that bile
is burning your esophagus
and gives you a nasty taste in your mouth,
among other things.
So, alkaline is the opposite.
Anything above seven up to
14 is a base or alkaline.
The stronger it is the closer
to 14 you're gonna get.
I'll come back to
buffers here in a second.
One thing it should be important to know,
and it's not gonna be tested
on but you should know,
every number is a factor of 10.
So if you have something that is acids
that has a pH of six,
and one that has five,
the one that's five is
10 times more acidic
than this one.
The one that's four is 100
times more acidic than this one.
And when you get down to here,
you get a million times
more acidic than this one.
So every number is a factor of 10
and the same thing is true
when you come up this way,
from eight to nine is a factor of 10,
eight to 10 is a factor of
100 and so on and so forth.
Well, let me give you another picture
which actually illustrates
this a little bit better,
'cause this one right
here will probably answer
all your questions that you need.
Here, hydrogen ions and
hydroxide ions at a pH
of seven is neutral.
The blue represents the hydroxide ions,
the orange represents the hydrogen ions.
Notice, that as the
hydrogen ions increase,
the hydroxide ions as
a result decrease, why?
Because hydrogen will start
mixing with hydroxide,
but as you keep pouring
hydrogen into there,
then the hydroxide will
just be neutralized over
and over until you have
relatively complete saturation,
which is what zero is.
Is where you're just completely saturated
with hydrogen ions, there
are no hydroxide ions,
and you have water mixed with
hydrogen ions and that's it.
It takes a bit to get to this point,
it takes quite a bit of hydrochloric acid
or whatnot but pure hydrochloric
acid has a pH of zero.
Look at your stomach
acids, it's a pH of one.
Now, I'm not gonna test
you on all of these numbers
but I feel it's important that we go over
some of these things
because of their relevance
to not only what we go over
later, but just life in general.
For example, let's say your stomach
is just massively producing too much acid,
how do you get rid of
some of that stomach acid?
Are you (mumbles)?
- [Student] Tums?
- [Instructor] Tums,
well, guess what Tums is?
- [Student] Antacid.
- [Instructor] It's a base.
An antacid, is a base.
So Tums has a pH of nine.
When you put it into your stomach,
the hydroxide ions are gonna
combine with the hydrogen
and neutralize each other.
Now, it's not equal neutralization.
In fact, remembering my chemistry days,
I had a lab partner, who
I immediately switched
after this incident, that
mix pure sodium hydroxide
with pure hydrochloric acid,
and the combined energy release literally
caused it to explode.
Thankfully, it was in a fume
hood and we were protected
from it, but he was a freaking moron.
So, that's not the reaction you get here.
That's why we don't use bases
that are on this extreme
because if you mix an acid
and the base of opposite extremes,
you get a tremendous release of energy.
So that's why we use very low weak bases
to neutralize some of our stomach acid.
Now if you have a lot of
heartburn, a lot of acid, splashy,
you can use milk of magnesia,
which has a slightly more alkaline,
it's a little bit stronger,
a pH of like 10.5 or whatnot.
That's what milk of magnesia
is is just a stronger base
that you can use.
Baking soda, again is a base.
This is why you typically
don't mix bleach,
which is down here with an oven cleaner,
because of the acid-basic causes a release
of the chemical reaction
which can kill you.
Your urine is slightly acidic
because you have by-products
like urea and uric acid
that come from your blood
and your protein metabolites and whatnot.
But notice, household
cleaners, oven cleaner,
bicarbonate, ammonia,
these are all cleaners
that we typically use.
You can use vinegar, you can
use soda, I've done it once,
it's really good to get
enough things you can use.
It's cheaper to use vinegar
than beer and Coca-Cola,
but you can use those to clean things.
It just it's not very fun to work with.
So bases and acids will do the same thing,
they just do it in different ways.
But they'll break down organic material,
and they'll allow you to
clean off various surfaces.
Look at our blood, it's just
slightly basic, it's about 7.4.
But this brings us to another concept
that you will need to know, back to here,
this is part of this as well
and I'm not on a tangent now,
this is a possible test question.
It's what we call a buffer.
So what is a buffer?
A buffer is not something
that neutralizes a solution,
it doesn't turn it to a pH of seven.
A buffer is just something
that keeps the pH the same,
resists changes in the pH.
For example, our blood is buffered
so that when we eat food
like sugars and whatnot,
and they get into our
bloodstream, or we get alcohol,
or we have carbon dioxide
buildup in our bloodstream,
those things would typically
cause our pH to start dropping.
But when the pH goes lower,
the cells don't function right.
So the blood prevents that
change, keeps your pH of 7.4.
That's another example of homeostasis.
Buffering is an example of homeostasis.
It prevents changes in the pH
so that your cells can
function as they should.
In some scenarios like our stomach acid,
that's buffered to a pH of one.
If we throw an antacid in
there, we get temporary relief,
but the body will rebound and say, no,
it needs to be at a pH of one.
So there are medicines that you can take
to counteract the body's natural tendency,
which is why people who
have chronic heartburn
and indigestion and
things like that usually
take those medicines instead of antacids
because it's more for chronic problems
with your stomach acid rather than acute
or in the moment problems.
So a buffer is just something
that prevents changes
in the pH.
It keeps it at the pH that
the system wants it to be.
And you'll find as we go through here
that not all of your cells
nor all the compartments
in your cells are neutral.
I mean, you can see all
the different examples.
Your urine slightly acidic,
your blood slightly basic,
your stomach is very acidic.
We'll show that even parts of the cells
have pHs of like 2.7.
So the reason why I want
you to know the pH scale
is because later on when we
say, oh, here's a lysosome.
It has a pH of 2.4 blah, blah, blah,
I'm not gonna go over pH again.
So you need to just be familiar with like,
oh, that's very acidic.
