Name __________________________________________________________Block ____________Date_____________
Partner(s) Name __________________________________________________________________________________
Amazing Milk – Day 2
Objective:
1. To apply the Scientific Method to help explain the behavior of milk and food coloring
2. To identify the independent and dependent variables and constants
3. To draw valid conclusions after analyzing the data
Question/Problem:
Why do milk and food coloring react the way they do when there is soap present?
Background Information:
Milk is the most “perfect food”. Why? Think about what kinds of nutrients our bodies need:
____water_________, _____vitamins_________, _____minerals_______, _____proteins_____, ____carbohydrates_____
and ____fats_________. Milk contains ___ALL______ of them!
Milk is ____87%______% water that holds ___dissolved__________
carbohydrates and proteins.
Milk also contains ____fats_________, but how is that possible, since
fats/oils and water don’t mix???
Milk is considered a Colloid, which is a ___suspension________ of
droplets of one liquid in another. In milk’s case, it is a mixture of two
immiscible (___’unmixable’_____) substances: droplets of __fats_______
suspended in the water, (which is also called milk ___serum________).
Because it is two immiscible substances suspended together, it’s a
special type of colloid called an ____EMULSION________________________
The fat droplets are ____small_________ enough to be suspended in the water so we don’t see them separate
from the milk. This type of solution, where particles are distributed evenly throughout, is called a
_____homogeneous_________ solution. Milk fat is a mixture of different fatty acids, which make up about
__90____% of milk fat. What makes different types of milk different? ___the amount of fat__________________
Skim milk = <_0.5________%
Lowfat milk = ___0.5-2_______%
Whole milk = at least ___3.25_______%
Half & Half = __10.5-18_______%
Vitamins & Minerals? Milk has ___calcium______________, ____magnesium_______, _____phosphate_________,
____potassium_______ and ______sodium__________. It contains vitamins ____A____, ___B6_____, __B12_____,
__C______, ___D___, ___E_____, ____K____ -- and many more!
Proteins are dissolved in the milk serum (water) and have 2 main types: __casein___________ and
___whey_________ proteins. The casein proteins are the ____solid__________ kind, and is what makes
__cheese_________ when it is separated from the whey proteins, which are found in the milk serum. Weak
chemical bonds hold the proteins in the solution.
Soap: How does it work?
Soap is an excellent cleanser because of its ability to act as an emulsifying agent.
An ___emulsifier_______ is capable of _____dispersing______________ or distributing one
liquid into another immiscible liquid. (Immiscible means that they
_____aren’t meant to be ______ mixed together, like oil and water).
Nearly all compounds fall into one of two categories: Hydrophilic (_____water-loving____________) or
hydrophobic (_________water-hating____________). Water and anything that will mix with water are
____hydrophilic___________________. Oil and anything that will mix with oil are ______hydrophobic__________.
When water and oil are mixed they ______separate_______________, which is why hydrophilic and
hydrophobic compounds just ____do___________ ______not_________ mix.
Soap is a molecule that has ____2_______ different ends. One end (“the head”) has a negatively-charged,
__polar_________ molecule that is _____attracted________________ to water. It is ______hydrophilic__________
(water-loving).
The other end of a soap molecule “the tail” is hydrophobic (water-___fearing_________). Its long,
nonpolar hydrocarbon chain ___does___________ ______not______ interact with water molecules. The
hydrophobic ends of soap are attracted to each other and cluster together, forming structures called
micelles. (see the picture below)
Grease and oil are ____nonpolar____________ and insoluble (_do____ ____not____ dissolve) in water. When
grease or oil is mixed with a soap-water solution, the soap molecules work as a bridge between
__polar________ water molecules and non-polar oil molecules. This means that while oil (which attracts
dirt) doesn't naturally mix with water, soap can suspend oil/dirt in such a way that it can be removed.
When soap and soiling oils are mixed, the nonpolar (hydrophobic-water __hating_________) ends of the
micelles break up the oil molecules. A different type of micelle then forms, with the dirt or oil molecules
_in_____ _____the_____ _____center_______. Thus, grease and oil and the 'dirt' attached to them are caught
inside the micelle and can be rinsed away.
A soap micelle has a hydrophilic head that is in contact with the water and a center of
hydrophobic tails, which can be used to isolate grime
After the soap molecules surround the dirt and grime, water molecules can then come through and
simply rinse the dirt away!!!
Suggested Materials:
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Water
Milk (whole milk, 2% milk, 1% milk, skim milk, half and half)
Dish Detergent (Dawn) in a small beaker
Food coloring (Red, Yellow, Blue, Green)
Cotton swabs
Plastic dinner plates
Graduated cylinder
Stopwatch