How does soap clean?
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DEMO
We will explore about the MAGIC MILK
but first let's have a preliminary activity: HOW MANY DROPS FIT ON EACH COIN?
Materials :
A cup of water
A variety of coins (a penny, a nickel, a dime, and a quarter)
Plastic straw
Directions:
Questions:
We will explore about the MAGIC MILK
but first let's have a preliminary activity: HOW MANY DROPS FIT ON EACH COIN?
Materials :
A cup of water
A variety of coins (a penny, a nickel, a dime, and a quarter)
Plastic straw
Directions:
- Set the coin on a flat surface.
- Fill a plastic pipette with water.
- Carefully squeeze out water drop by drop from the pipette onto the coin.
- Count how many drops fit on the coin before the dome breaks and the water spills over.
- Keep track of your results
Questions:
- Which coin holds the most water?
- Why does a dome form when you drop water on the coin?
- Why does the dome eventually collapse?
SURFACE TENSION
The answer to this lies in the structure of the water molecule itself.
Water is a polar molecule, meaning that it has a positive end and a negative end.
The negative end of one molecule is attracted to the positive end of another molecule (similar to a magnet), which makes the molecules stick together tightly.
The molecules on the surface are pulled inward and they stick together so strongly that they form a dome. This is called surface tension.
Eventually, though, gravity overcomes this force and the dome breaks, spilling water over the sides of the coin. :)
The answer to this lies in the structure of the water molecule itself.
Water is a polar molecule, meaning that it has a positive end and a negative end.
The negative end of one molecule is attracted to the positive end of another molecule (similar to a magnet), which makes the molecules stick together tightly.
The molecules on the surface are pulled inward and they stick together so strongly that they form a dome. This is called surface tension.
Eventually, though, gravity overcomes this force and the dome breaks, spilling water over the sides of the coin. :)
YOUR TURN !
ACTIVITY: MAGIC MILK.....DANCING COLORS...BUT WHY? WHAT IS GOING ON..?
Materials:
Milk
A bowl
Food Coloring
Liquid dish soap
Toothpick
Directions:
Questions:
What happens chemically?
ACTIVITY: MAGIC MILK.....DANCING COLORS...BUT WHY? WHAT IS GOING ON..?
Materials:
Milk
A bowl
Food Coloring
Liquid dish soap
Toothpick
Directions:
- Pour milk in a dish. You don’t want or need much, just a thin film that covers the bottom of the dish.
- Squeeze a few drops of food coloring or liquid water colors into the milk.
- Dip the end of the toothpick into the dish soap and then into the center of one drop of colored milk. Don’t stir it! Watch the color erupt and scatter like a firework in the sky!
Questions:
What happens chemically?
There are actually a few different things happening:
FIRST: The soap is distrupting the surface tension of the milk.
REMEMBER: the cool little dome that water forms at its surface?
All liquids, including milk, act this way to some extent.
SECOND: Adding soap interrupts those bonds along the surface, making the surface molecules spread out and the colors explode like fireworks!
REMEMBER: HYDRO -PHOBIC ( water fearing) and HYDRO -PHYLIC (water loving) MOLECULES :)
NOW YOU ALSO KNOW HOW SOAP AND DETERGENTS CLEAN...
REMEMBER
Soap emulsifies grime, which means oily stains bind to the soap so they can be lifted away with water. Detergents act as surfactants, lowering the surface tension of water so it can interact with oils, isolate them, and rinse them away.
FIRST: The soap is distrupting the surface tension of the milk.
REMEMBER: the cool little dome that water forms at its surface?
All liquids, including milk, act this way to some extent.
SECOND: Adding soap interrupts those bonds along the surface, making the surface molecules spread out and the colors explode like fireworks!
REMEMBER: HYDRO -PHOBIC ( water fearing) and HYDRO -PHYLIC (water loving) MOLECULES :)
NOW YOU ALSO KNOW HOW SOAP AND DETERGENTS CLEAN...
REMEMBER
Soap emulsifies grime, which means oily stains bind to the soap so they can be lifted away with water. Detergents act as surfactants, lowering the surface tension of water so it can interact with oils, isolate them, and rinse them away.