Milk ProjectMilk Project

Materials:Materials:

- Milk - Milk - Pie tin- Pie tin- Food coloring (red, yellow, - Food coloring (red, yellow,

green, blue)green, blue)- Dish-washing soap - Dish-washing soap

- Cotton swabs- Cotton swabs

Steps:Steps:11. . PourPour enoughenough milkmilk in the in the

pie tin to completely cover the pie tin to completely cover the bottom and allow it to settle. bottom and allow it to settle.

22. . Add oneAdd one dropdrop of of each of the foureach of the four colors colors ofof food coloringfood coloring - - red, yellow, red, yellow, blue, and green - to the milk. blue, and green - to the milk. Keep the drops close together Keep the drops close together in the center of the plate. in the center of the plate.

3. Use a clean cotton swab. 3. Use a clean cotton swab. PredictPredict what will happen when what will happen when you touch the tip of the cotton you touch the tip of the cotton swab to the center of the milk. swab to the center of the milk. It's important not to stir the mix It's important not to stir the mix just touch it with the tip of the just touch it with the tip of the cotton swab. cotton swab.

4. Next, place a 4. Next, place a dropdrop of liquid of liquid dish soapdish soap (“Dawn” works well)(“Dawn” works well) on the on the other tip of the cotton swab. other tip of the cotton swab. Place it in the middle of the Place it in the middle of the milk. Hold it there for 10-15 s. milk. Hold it there for 10-15 s.

Observed:Observed:Look at thatLook at thatburst of color! burst of color! It's like the It's like the 4th of July in a 4th of July in a bowl of milk: bowl of milk: mini-explosionsmini-explosions of color. of color.

5. 5. Add Add anotheranother drop of soap to the tip drop of soap to the tip to the cotton swab and try it again. to the cotton swab and try it again. ExperimentExperiment with placing the cotton with placing the cotton swab at different places in the milk. swab at different places in the milk. ObserveObserve that the colors in the milk that the colors in the milk continue to move even when the continue to move even when the cotton swab is removed. cotton swab is removed.

Why does the food coloring in the milk move? Why does the food coloring in the milk move?

How does it work?How does it work? HypothesizeHypothesize how and why you how and why you

think that this occurs.think that this occurs.

What makes the What makes the

swirling of the food swirling of the food

coloring occur? coloring occur? TalkTalk about it with about it with

your partner.your partner.

Then Then writewrite your ideas in your your ideas in your science journals. science journals.

What make the swirling of the What make the swirling of the food coloring occur?food coloring occur? Liquid soap wrecks the Liquid soap wrecks the surface surface

tensiontension by breaking the cohesive by breaking the cohesive bonds between water molecules and bonds between water molecules and allowing the colors to zing allowing the colors to zing throughout the milk. throughout the milk.

The liquid soap weakens the milk’s The liquid soap weakens the milk’s bonds by attaching to its fat globules bonds by attaching to its fat globules because of its bipolar characteristics because of its bipolar characteristics ((hydrophilichydrophilic, , water-loving,water-loving, on one end on one end and and hydrophobichydrophobic, , water-fearingwater-fearing on the on the other). other).

What is it about soap that What is it about soap that allows for oils to be dissolved?allows for oils to be dissolved? The soap's The soap's hydrophilichydrophilic end dissolves in end dissolves in

water and its water-fearing end attaches to water and its water-fearing end attaches to a fat globule in the milk. a fat globule in the milk.

The soap molecule’s water-loving part is The soap molecule’s water-loving part is polar and the water-fearing is nonpolar. polar and the water-fearing is nonpolar. When we wash with water alone, we When we wash with water alone, we cannot dissolve oils, but when soap is cannot dissolve oils, but when soap is added to the water, the polar end of the added to the water, the polar end of the soap molecules is attracted to the polar soap molecules is attracted to the polar end of the water molecules and the end of the water molecules and the nonpolar end is absorbed into the oil. A nonpolar end is absorbed into the oil. A particle (larger than a molecule) is formed particle (larger than a molecule) is formed and the oil can be washed away. and the oil can be washed away.

What is it about milk that makes it What is it about milk that makes it have surface tension? have surface tension?

Since milk is mostly water, it has Since milk is mostly water, it has surface tensionsurface tension like water. The like water. The drops of food coloring floating drops of food coloring floating on the surface tend to stay put. on the surface tend to stay put. Water has surface tension Water has surface tension because of the attraction of all of because of the attraction of all of the molecules, the molecules, cohesioncohesion. In the . In the bulk of the liquid each molecule bulk of the liquid each molecule is pulled equally in all directions is pulled equally in all directions by neighboring liquid molecules.by neighboring liquid molecules.

AtomAtom: the smallest basic unit of : the smallest basic unit of matter.matter.

ElementElement: one type of atom (each : one type of atom (each have different number of protons) have different number of protons)

MoleculesMolecules: two or more atoms held : two or more atoms held together by a chemical bond.together by a chemical bond.

CompoundCompound: atoms of different : atoms of different elements bonded together in a elements bonded together in a certain ratio.certain ratio.

Unique Properties of water Unique Properties of water

This experiment This experiment can explain can explain surface tension surface tension and polarity. and polarity.

The explanation The explanation of surface of surface tension can tension can show all of the show all of the things that things that make water so make water so useful for life. useful for life.

So, water’s surface tension comes So, water’s surface tension comes from its polarity so it attracts itself. from its polarity so it attracts itself. This makes certain things like the This makes certain things like the capillary effect possible so that capillary effect possible so that plants may “drink” water from the plants may “drink” water from the ground.ground.

This also This also explains the explains the structure of ice structure of ice and why the and why the solid form of solid form of H2O is less H2O is less dense than the dense than the liquid stage.liquid stage.

Phospholipid BilayerPhospholipid Bilayer

This characteristic This characteristic behavior of water and behavior of water and oil is of critical oil is of critical importance for living importance for living things, determining things, determining many properties of the many properties of the cell cell

PhospholipidsPhospholipids, the , the building blocks of the building blocks of the cell membranes, are cell membranes, are both both hydrophilic and hydrohydrophilic and hydrophobicphobic..

The The hydrophobichydrophobic pair of fatty acids pair of fatty acids are embedded in the middle of the are embedded in the middle of the membrane.membrane.

The The hydrophilichydrophilic phosphate projects phosphate projects outward forming outward forming hydrogen bonds hydrogen bonds with a tight, organized layer of with a tight, organized layer of water on each face of the water on each face of the membrane.membrane.

Do you drink homogenized milk?Do you drink homogenized milk? This experiment explains what This experiment explains what

homogenizationhomogenization of milk is. Milk is of milk is. Milk is made up mostly of water and made up mostly of water and then equal parts of protein, fats, then equal parts of protein, fats, and sugar. and sugar. HomogenizationHomogenization breaks up the fat and spreads it breaks up the fat and spreads it throughout the milk into tiny throughout the milk into tiny pieces of fat called globules. pieces of fat called globules.

When the milk was first placed When the milk was first placed into the carton, it was still and did into the carton, it was still and did not move. Even when the food not move. Even when the food coloring was added to the milk, coloring was added to the milk, things were still quiet. This is things were still quiet. This is because the fat globules were because the fat globules were steady and undisturbed. steady and undisturbed.

When the soap hits the milk, things When the soap hits the milk, things begin to move. The soap breaks up begin to move. The soap breaks up the fat globules and lets them spread the fat globules and lets them spread across the surface of the milk. When across the surface of the milk. When you add soap, the weak chemical you add soap, the weak chemical bonds that hold the proteins in bonds that hold the proteins in solution are altered. solution are altered.

As the globules break and expand, As the globules break and expand, they create movement in the milk. they create movement in the milk. Normally you would never notice Normally you would never notice this, but the food coloring shows how this, but the food coloring shows how the surface of the milk moves and the surface of the milk moves and changes in response to the soap changes in response to the soap breaking up the fat in the milk.breaking up the fat in the milk.

How soap worksHow soap works Soap has a part of the molecule Soap has a part of the molecule

that is that is polarpolar and and nonpolarnonpolar. . When washing with water alone, When washing with water alone, it will not dissolve oils, but when it will not dissolve oils, but when soap is added to the water, the soap is added to the water, the polar end of the soap molecules polar end of the soap molecules is attracted to the polar end of is attracted to the polar end of the water molecules and the the water molecules and the nonpolar end is absorbed into nonpolar end is absorbed into the oil. A particle (larger than a the oil. A particle (larger than a molecule) is formed and the oil molecule) is formed and the oil can be washed away with water. can be washed away with water.

Soap

In this experiment the liquid In this experiment the liquid soap weakens the milk’s bonds soap weakens the milk’s bonds by attaching to its fat globules by attaching to its fat globules because of its bipolar because of its bipolar characteristics (characteristics (hydrophilichydrophilic on on one end and one end and hydrophobichydrophobic on the on the other). The soap's hydrophilic other). The soap's hydrophilic end dissolves in water and its end dissolves in water and its water-fearing end attaches to a water-fearing end attaches to a fat globule in the milk. fat globule in the milk.

What is the polar side of the polar side What is the polar side of the polar side of soap called?of soap called?