Ice Cream Lab
Background
Materials
Procedure
Matter
• What is matter? Anything that has mass
and takes up space
• What are the three main states (or phases)
of matter? Solid, Liquid, and Gas
How much energy is present in
each state of matter? (relatively speaking)
• Solids - particles are
vibrating in place; not
much movement
• Liquids - particles move
around; sliding past each
other
• Gases - particles are
moving all over the place;
moving in straight lines
and bouncing off things
Solid
Gas
Less
Energy
More
Energy
Physical States of Water
STATE
WHAT WE
CALL IT
CHEMICAL
COMPOSITION
SOLID
ICE
H2O
LIQUID
WATER
H2O
GAS
VAPOR
H2O
So, a change of state is a physical change not a chemical change.
We want answers.
We want the truth.
Gas
100
WAIT - If the energy
is changing why
isn’t the temperature?
L&G
Liquid
S&L
0
Solid
The energy is being absorbed or
released by the matter as it
changes states!
No, not from Pennsylvania to West Virginia, from
Solids to Liquids and Liquids to Gases and vice versa.
So, what does this have to do
with ice cream?
• When we make ice cream we start with a
milk and sugar mix – A LIQUID
• And we end up with a frozen delight – A
SOLID
• We use ice and salt to make that happen and
the ice has to melt.
How does the process work?
• Water has colligative properties.
• When an impurity (such as salt) is added to water,
the boiling point is elevated and the freezing point
is depressed.
• That is why your parents put salt on an icy
sidewalk. The ice will melt because salty ice has a
lower freezing point than just ice and hopefully it
is not cold enough to keep salty ice frozen.
Back to ICE CREAM
• We have two different phase changes
occurring.
– Ice melting (Solid to Liquid)
– Ice cream mix freezing (Liquid to Solid)
For these phase changes to occur energy is
transferred – from the ice cream mix to the ice.
Ice Cream Lab - materials
• Ingredients
–
–
–
–
–
–
.5 liters milk
110 ml sugar
2.5 ml vanilla
1.5 liters ice
180 ml salt
toppings
Hey, wait. My
measuring cups
are in English
Units. Uh-oh,
CONVERSIONS
Ice Cream Lab – materials
in English units
• Ingredients
–
–
–
–
–
–
.5 liters milk = .53 quarts ~ 2 cups
110 ml sugar = 3.63 ounces ~ ½ cup
2.5 ml vanilla = .5 teaspoon
1.5 liters ice = 1.6 quarts ~ 6 cups
180 ml salt = 5.94 ounces ~ ¾ cup
toppings
Ice Cream Lab – more materials
•
•
•
•
•
•
1 gallon size Ziplock bag
1 quart size Ziplock bag
measuring cups
measuring spoons
spoons
bowls
Procedure
1.
2.
3.
4.
5.
6.
Put milk, sugar, and vanilla into quart bag. Squeeze out as much air as
possible and close bag securely.
Place quart bag in gallon bag. Add ice and salt. Seal large bag.
Knead the small bag inside the large bag to expose the mixture to the cold
temperatures. You can also roll the bag back and forth on the lab table.
Knead for about 10 minutes. Check to see if the mixture is frozen. If not
knead longer.
When frozen remove smaller bag. Carefully open it, being sure to wipe seal
of salt water first. Place in cups, top, enjoy.
Answer and turn in analysis questions.
OKAY
Go for it.