Penny Slider Test

What did you do last time? evaporates freeze volume mass density particles PRINT the word next
to the image on the next slide.
Chem - L5
Can you CHANGE the density
of a LIQUID?
 Let's experiment! You will need: salt raw egg water
in a tall
clear glass spoon 1 2 Add salt
a tablespoon
at a time.
STIR. Does the egg sink or float?
 To make
the egg
float:
 What can
cause the egg
not to float?
 It will not float IF:

1. Too little salt is added.
2. The salt has not been
     stirred into solution.
3. The egg is too small
     and dense to float.
4. The egg has been cooked.
 Lower the egg
gently into a glass
2/3 full of water.
 3 To suspend the egg
in the middle of the glass:
 Why does the egg sink and then float? The egg stays between the two layers:
the more dense salt solution below and
the less dense clear water above. Pour off some salt water.

Slowly add clear water
above the egg.

What happens? The egg is more DENSE than the clear water-- so it sinks.
The egg is less DENSE than the salt water-- so it floats. It is easier to float
in salt water,
because salt water
has greater density
than fresh water. Sink or Swim Is it easier
to float in
salty ocean water
or a pool of
fresh water?
To answer that question
let's first consider:

HOW SMALL,
IS SMALL? Click on the red
question mark
the for answer. HOW
 HOW did the salt INCREASE
the density of water? Pour half of the water
into another spoon. Of course!
What a silly question. Are both portions still water?
Start with a tablespoon of water. HOW SMALL IS SMALL? What if you do it again.
Divide each portion in half.
Is each half-of-a-half still water?
Another silly question!

What if you keep going?
Divide the water in half,
over and over again,
into smaller and smaller portions. YES!!!
 If you could divide
a tablespoon of water
in half about 78 times,
you would have divided
the water to its limit.
WHY? Is there some smallest portion
into which you can divide water
before it stops being water? You will be down to
ONE molecule of water
in each spoon.

That’s the limit.
The END.
WHY? WHY?
If you could divide
the ONE water MOLECULE
any further,
it would no longer
BE a water MOLECULE.

It would be BROKEN into ATOMS. Here’s what a water
MOLECULE looks like--
sort of, if you could see it,
which you cannot.

It’s too small. 2 hydrogen
atoms 1 oxygen
atom There are many ways to picture
the water molecule: H2O. WATCH! What does the red "O"
stand for? What does the "H"
stand for? Oxygen Hydrogen HOW did adding SALT
change the density of WATER? Find these items:

Small cups
Marbles
Puff balls Click on the cup with the greater density? NEXT NEXT NEXT BOTH CUPS HAVE
THE SAME DENSITY Salt water contains dissolved salt,
sodium chloride (NaCl).

The dissolved salt increases
the MASS of the water
without much increase in VOLUME.

So SALT water is MORE dense
than PLAIN water.

Like the puff balls
compressed between the marbles,
SALT WATER has more ATOMS packed
into the same space as pure water. MASS
is the
amount
of matter
in an object.
 Remember: Volume IS the space an object takes up. Density IS mass/volume Objects that are more dense
than water will do what? Sink FLOAT Less dense objects will? Mass, Volume and Density Song Does an object with
greater density than
water float or sink in water What is the
density of water What is density How did you make
the egg float 1 2 3 4 5 Will a raw egg usually sink
or will it float in plain water You added salt to water
to increase its density. SINK 1 g/cm³ density = mass / volume sink