- [Voiceover] Water itself is all around us.
Basically, our life depends on water.
So a couple things about water we need to know.
First off, water molecules are polar.
But what does that mean?
Water molecules are two hydrogen and one oxygen, H2O.
Because of the way they're arranged,
with an oxygen molecule in the middle,
and then two hydrogens on each side,
gives us H bound to an O bound to an H.
This gives a polar configuration.
It means that one portion is a little more negative,
while the other portion of the molecule
is a little more positive.
Instead of the whole entire molecule
being positive or negative, it has both,
a slight polarity on one side,
a slight positive aspect on one side,
and a slight negative aspect on the other side.
When we have our water in our body, it's liquid.
It's kind of a good thing because
if the water in your body was ice, solid,
it might be a little problem moving around.
If it was vapor, as in gas,
it could also cause some problems there.
Water is liquid from what temp to what temp?
From roughly 0 degrees Celsius to 100 degrees Celsius,
or if you want to look at Fahrenheit, it's
32 degrees Fahrenheit up through 212 degrees Fahrenheit.
That whole range, water is primarily liquid.
Now at each end, the high and low end,
there are little variations depending on
altitude and a few other things that go into it.
But for the most part, it's liquid.
Water is great at absorbing energy.
It can absorb energy, especially heat energy,
and that's what allows it to warm up.
When you put a pot of water on the stove to boil,
does it boil immediately?
No.
It takes the heat energy from the stove,
takes it into the water, absorbs it, holds it,
and gets warmer and warmer.
Water is just a great way to hold and store energy.
Biological solvent.
Well, a solvent is something that has other components
basically dissolving into it.
Think about salt water.
You can grab a glass of water, pour some salt into it.
The salt will dissolve into the water.
The water is a solvent.
Same thing happens inside your body.
Water allows numerous other molecules
to dissolve into it.
Body temp regulation.
Can you think of a way that water
helps you regulate your body temperature?
Now you may have thought of sweating, sure.
By sweating, you're releasing water
that's absorbing heat energy and then evaporating,
helping to cool the body down.
Or if you want the other way, water holds heat
and prevents heat from being lost as quickly.
So solvent, I already said solvent
is when something else can dissolve into it.
Now we'll put the term liquid there,
because it's kind of hard to have things
dissolve into a solid or a gas.
It's a liquid that has other substances.
It could be anything that will allow it
to be dissolved into.
Salt dissolves into the solvent water, for example.
Water is a solvent.
In that case, the solute would have been salt.
The solute is any substance that can
dissolve into another substance.
Hydrophilic.
Well, water is great at being hydrophilic.
Hydro, the prefix, H-Y-D-R-O, hydro refers to water.
The second half, philic, P-H-I-L-I-C,
philic means love.
Hydrophilic means water loving.
Any hydrophilic molecule is attracted to water.
It can interact with water.
Do you think, I don't know, oil is hydrophilic to water?
Does the oil easily interact with water?
Does the oil easily mix with water?
No, oil and water, they don't really mix at all.
So oil would not be hydrophilic.
Oil would be hydrophobic.
Hydrophobic are molecules that do not
want to interact with water.
They cannot dissolve in water.
If you pour oil into water,
I don't care how much you shake it up,
you get tiny little droplets of oil on there
that will slowly start to group back together
to eventually form an entire layer of oil
separate from the water.
So hydro, water, phobic, fear.
Hydrophic is water fearing.
Here's an example showing the sodium ions and chloride ions.
You can see that the NA+,
the little lightly colored, almost orangish-yellow there,
and A+ is sodium.
The green, the CL- is chloride.
Sodium chloride is salt.
When sodium chloride is arranged
in that alternating pattern you see there,
that forms a salt crystal.
Put a salt crystal in water, what will happen?
The water molecules, which is the two small blue spheres,
and a large red sphere.
Each blue sphere is a hydrogen.
Each red sphere is oxygen.
You can see there's two hydrogens
and one oxygen together.
What these water molecules will do,
they will surround each individual sodium
or chloride ion, slowly picking the crystal apart,
slowly allowing the salt crystal to dissolve.
But water is not just hydrogen ions.
It has a few other things going on.
Those hydrogen ions that are part of water,
they can be used to also indicate
acidic or basic solutions.
An acid, for instance.
I bet you guys have probably heard of
some type of acid.
Maybe it's hydrochloric acid, sulfuric acid, nitric.
There's many different acids out there.
Acids in general are going to donate a hydrogen ion.
What that means is, they're going to give off
or give away a hydrogen ion.
The case of hydrogen and then chlorine, hydrochloric acid,
it's one hydrogen and one chlorine.
In hydrochloric acid, they can break apart.
The hydrogen ion is released.
The more hydrogen ions, the more acidic a solution becomes.
Therefore, if you increase those hydrogen ions,
then that means you are going towards
the acidic side of things.
Well, bases, they're the exact opposite.
Sodium hydroxide, NAOH, is a great base.
It accepts hydrogen ion.
These bases are going to take the free hydrogen ions,
the ones just floating around.
They'll take them and bind them.
By binding the hydrogen,
it lowers the hydrogen ion concentration.
The lower the hydrogen ion concentration,
the free hydrogen ions, not the ones bound,
just the free ones floating around,
the lower the hydrogen ion concentration,
the more basic the solution will be.
These acids and bases, they're measured on this pH scale.
The pH scale is based on the concentration of hydrogen ions.
The most acidic will have the highest
concentration of hydrogen ions.
The most basic, which is the other side of the scale,
will have the least hydrogen ion concentration.
Here is your pH values, anywhere from 0,
all the way up to 14.
Now, the pH of 7, you see it's right next to the neutral pH.
That's pretty close for human blood, tears,
a lot of bodily fluids.
Now they're not exactly 7.000, but they're close.
As you look down into the reddish area, that more acidic,
you can see you get numbers decreasing,
7, 6, 5, 4, 3, 2, 1, 0.
That's talking about the concentration of hydrogen ions.
As you get down to tomatoes, vinegar, and lemon juice,
they're all pretty acidic.
But go up towards that blue side of things,
8, 9, 10, 11, 12, 13, 14,
well those are becoming more basic,
or more alkaline.
Baking soda, ammonia, bleach, drain opener,
all very basic.
We have our acidic, high hydrogen ion concentration,
basic or alkaline, low hydrogen ion concentration.
But your body needs to stay within a certain range,
so thankfully we have buffers.
A buffer is meant to minimize the pH change.
Doesn't matter how much acid or base it is initially.
It helps it damper or prevent a very quick change.
It creates a more stable environment in the body fluids,
keeping the pH in a smaller, narrow range.
For example, your blood pH typically sits around
7.35 to 7.45.
Just a little bit basic.
Notice it's only a 0.1 difference,
7.35 to 7.45.
Your body keeps the blood within that pH.
It's all because of buffers to minimize
the change up or down.
Now, one of the most prevalent buffering systems
in the human body is the carbonic acid bicarbonate system.
The HCO3- is going to be your bicarbonates.
H2CO3 is a carbonic acid.
If you notice, the carbonic acid
can donate a hydrogen ion.
One hydrogen ion is released,
see how there's a free hydrogen ion,
and therefore HCO3.
We have this buffering system,
carbonic acid bicarbonate.