How Does Shampoo Work?

Have you ever wondered while rubbing shampoo into your hair how this colorful, sometimes clear soapy substance can clean hair?

Shampoo is made up of molecules such as ammonium lauryl sulfate that bond with the dirt and sweat on your hair. This bonding action helps shampoo clean your hair of dirt. Water helps by adding pressure to the shampoo-dirt components and rinsing these components out of your hair and down the drain.

Okay, so these shampoo molecules bond with dirt. How? Well, in the case of ammonium lauryl sulfate, the chemical detergent is similar to the dishwashing or laundry detergent used to wash dishes or clothes. Ammonium lauryl sulfate is a harsh chemical as it needs to bond aggressively with the dirt on your hair to clean it. Sodium laureth sulfate is also a detergent found in shampoos, but it is a little gentler to hair. Guar hydroxypropyltrimonium chloride is another type of chemical found in shampoos that adds volume and smoothes hair. This chemical helps make your hair easy to comb. Diethicone helps soften hair by coating the outer hair surface.

Shampoo is not just chemicals. It is actually 80 to 90% water. But, just using water won't really leave your hair clean, soft or comb-able. Rather, it is the 2 to 8% of detergents such as the chemicals listed above that really do the critical work of shampoo. The remaining 1% of shampoo is added fragrances or scents. The type of fragrance or scent your shampoo has really doesn't affect how clean your hair is, but it does affect the scent you smell when you are washing and brushing your hair.

So, shampoo helps clean hair; does it matter how much is used? The amount of shampoo should be about the size of a quarter. Anything less will not be enough to bond to all the dirt and sweat in your hair. Anything more is just wasting shampoo, water and your time. Too much shampoo can also leave your hair feeling dull as you wash away vital nutrients from your hair if you overwash it. Using a little more than a quarter may be necessary, though, if you were outside playing in a muddy creek.

One good way to tell if you are using too much shampoo is the amount of lather produced. Lather forms when the shampoo gathers around air instead of the oil from your hair. Dirt and oil actually destroy lather. If you have too much lather, you used too much shampoo. Remember, shampoo is to clean your hair, not the air.

Little Lion Experiment:

Materials:

• A piece of polystyrene clear plastic
• A soda straw to use as a dropper
• A little shampoo
• A centimeter ruler
• A toothpick, wire or some other small diameter "stick-like tool" that you can coat with shampoo

Steps:

1. Place your polystyrene sheet on a flat level surface where you can observe easily from the side and from the top.
2. Place some drops of water on the sheet using your straw. You can do this by sticking your straw into a glass of water, placing your index finger over the hole and pulling out the straw. When you loosen your index finger slightly, you can control the amount of water that you drop out. Make some big drops and some small ones.
3. Measure the diameters of the drops and looking from the side, sighting with your ruler, estimate their height. Finally, and again looking from the side, estimate the angle at which the water contacts the polystyrene. Why are these drops all circular? Make a plot of the height versus the diameter? What do you conclude? Make a plot of the contact angle versus the diameter. Again, what do you conclude?
4. Take your "tool" (no shampoo yet), and push it across and through a water drop (i.e. move it parallel to the polystyrene). Describe what happens. You may want to try it several times to check what things happen every time.
5. Dip your "tool" in your shampoo and shake off the excess (we do not want any big drops). Now push your "tool" into the edge of one of the water drops. What happens? Now push it across and through a drop. What happens? How is this different from what happened before you dipped it into the shampoo?

This experiment was described by the Science and Technology Center, University of Texas at Austin.

What Makes a Rainbow?

We have all seen beautiful rainbows across the sky after rain. But how does a rainbow form? Rainbows are usually formed when sky is full of clouds and it is about to rain. In order for a rainbow to form, we need two things, rain and sun.

When we look at sunlight most of us think of it as just one color: white, clear or blue. Sunlight is actually made up of all colors of light. All colors, which we see in rainbow, are originally there in sunlight. However, we do not see them in sunlight because they are mixed together. In the same way, if you take blue and yellow paint and mix them on paper you will see green paint. This green paint, as you know, contains both blue and yellow color; however, you only see green. Sunlight is the same way: when you mix all the colors of light together you get white light or sunlight.

Now that we know so much about light, let's look at what else make rainbows: rain. Rain comes from clouds. Clouds in the sky contain millions and millions of tiny raindrops. Rainbows are caused by the bending of sunlight as it passes through the raindrops. The raindrops act like miniature prisms. As white light enters the prism, it is separated into the individual colors of light. Both prisms and raindrops separate light based on the wavelength of the light. Light moves in waves, just like the waves in the ocean, and each color has a different length of wave. The longer the wavelength the slower the light color moves, purple is the fastest light and red is the slowest. The spectrum, or band of colors which make up the "white light" leaves the prism as separate bands of color. The more slowly a wavelength of light travels, the more it is bent by the prism. That is why the colors seen in the rainbow are always in the order red, orange, yellow, green, blue, indigo, and violet. The red light travels more slowly than violet light so it is bent more.

What Makes Soda Pop?

Pop, soda or soda-pop bubbles and fizzes because of the gas called carbon dioxide (di-ox-ide). Carbon dioxide is same gas that we breathe out (We breathe oxygen in). When soda-pop is made a whole lot of carbon dioxide is pushed into a pop can. The can is then sealed and pressure inside the can is created. The pressure inside the can is higher than the pressure outside the can. This is why the can will "pop" when you open it. The amount of carbon dioxide that the liquid soda-pop can hold depends on the temperature and pressure of the liquid. The amount of a gas that a liquid can hold is called the solubility (sol-u-bil-ity) of the gas. The "pop" at the opening is caused by carbon dioxide being released from the liquid soda-pop since the amount of gas the liquid soda-pop can hold is changed when the pressure is changed.

If you take a soda-pop right out of the refrigerator and open it up, less carbon dioxide will be given off than if you opened it after it was sitting in the sun for hours. If you lower the temperature of the soda-pop the solubility of the carbon dioxide is increased, so more gas will stay in the liquid soda-pop.

Little Lions Experiment:

1. See if the laws of solubility hold true. Take a can of soda-pop that has been in the freezer for an hour or two, until it is cold, but not frozen. Wash out a styrofoam cup and lid from a gas-station or a fast food place, take a straw and put it in the cup. Tape around the opening in the lid where the straw goes. Take a second straw and insert in the straw from the cup and tape any joints between the straws. Insert the far end of the straw in a clear glass with water in it. You want to try to prevent any gas from leaving the cup, other than what goes through the straw to the water. Take the styrofam cup and fill it with your soda-pop. Close the lid quickly to prevent any escaping of gas. Place the cup in warm to hot water. Do not boil water with the cup in the pan or the cup will melt. Notice the carbon dioxide bubbling in the water. Does the amount of carbon dioxide given off change when you put the cup in the warm water?
2. Find hidden gases! Look around the house for other gas hiding in liquids. Some of these imposters are hydrogen peroxide, bleach, ammonia, perfume, and cologne. Notice how some of these hidden gases smell, and some smell bad! This is because gas molecules move around a whole lot more then liquid molecules, so our nose picks them up better.

How Was Ice Cream Developed?

You know your favorite flavor and that you have to eat it fast before it melts, but do you know the science of ice cream? Believe it or not, ice cream as we know it has had a pretty rocky road in order to be as yummy and available as it is today. In "The History of Ice Cream," written by the International Association of Ice Cream Manufacturers (IAICM), Washington DC, 1978, a very detailed history of the cold and creamy treat is described. The funny part about the book, though is that most of the early history of ice cream remains unproven folklore.

And so the story goes...once upon a time, hundreds of years ago, Charles I of England hosted a banquet for many of his friends and family. The meal featured the greatest foods of the day and ended with a cold treat that resembled fresh-fallen snow. The guests as well as Charles loved the cold treat and Charles paid the cook 500 pounds a year to only serve it at his Royal table. The cook kept the secret until Charles was beheaded in 1649.

This tale along with others provides some insight into the evolution of our country's most popular dessert. Most likely, ice cream was not invented, but rather came to be over years of similar efforts. Even the Roman Emperor Caesar is said to have sent slaves to the mountains to bring snow and ice to cool and freeze the fruit drinks he was so fond of. Centuries later, the Italian Marco Polo returned from his famous journey to the Far East with a recipe for making water ices resembling modern day sherbets.

These tales are interesting and help to connect history with food science as well as cultural traditions. Unfortunately, no real historical evidence supports any of these stories. The tales might just have been a marketing plan of the nineteenth-century ice-cream makers and vendors. When it comes to actual facts, it seems that ice cream may have had its first appearance in China.

Although the actual history of ice cream is rocky, some of the inventions that were made to improve ice cream are a little more know. The first improvement in the manufacture of ice cream (from the handmade way in a large bowl) was given to us by a New Jersey woman, Nancy Johnson. In 1846, she invented the hand-cranked freezer. This device is still familiar to many. By turning the freezer handle, they agitated a container of ice cream mix in a bed of salt and ice until the mix was frozen. Because Nancy Johnson lacked the foresight to have her invention patented, her name does not appear on the patent records. A similar type of freezer was, however, patented on May 30, 1848, by a Mr. Young who at least had the courtesy to call it the "Johnson Patent Ice Cream Freezer." Commercial production was begun in North America in Baltimore, Maryland, 1851, by Mr. Jacob Fussell, now known as the father of the American ice cream industry. Right in our backyard at Penn State, tremendous research on how to make ice cream from making the best flavors to extending its shelf-life have been occurring for decades. Besides several tasty flavors, the Penn State Creamery offers a course (Ben and Jerry even took it) and a little museum. Maybe one day this summer when you are hot and in the mood for a sweet taste and a food science lesson you should ask your parents to take you down 322 E to Happy Valley. In the meantime, share your secrets on ice cream to your friends and family.

Little Lions Experiment:

Fill up a paper Dixie cup with water and another one with fruit juice. Only fill up the cups to about 3/4 full as liquid expands as it freezes (molecules in ice are bigger than they are in a liquid state). Then, place them carefully in the freezer and time how long they take to freeze. Monitor the process and see where ice forms first. Try to think why ice forms on the top before in the middle. Then, time to see which freezes first water or fruit juice. You can freeze other liquids such as milk or solids just as pudding or yogurt, if you want. Try to determine if a substance's state (liquid or solid) affects its freezing time as well as the material's density, i.e. has more sugar, food ingredients in it. Then, enjoy your frozen treats. Be careful, not to give yourself a "brain-freeze" as cold foods can cause mild nerve triggers that can hurt your head.

How Do Firecrackers Work?

I am sure by this time of you most of you have seen, heard and even fired firecrackers. But, do any of you know what makes firecrackers crack, bang, and light up? If not, I will explain it to you. It is actually quite simple--it's science.

Today's firecrackers use gunpowder. But, firecrackers came long before gunpowder. The actually date centuries across to China. In fact, the firecrackers were entirely natural or organic. They were probably an accident, too. It is said that these early firecrackers came about because someone tending a fire ran short of fuel and decided to throw in a few lengths of green bamboo. Bamboo is a type of plant. The bamboo, knobby round reeds, would blacken, smoldered, and hissed. Surprisingly, they would end up exploding. How did this happen?

The answer is that inside bamboos are pockets of air and sap. These pockets, when weakened by the fire, will expand and eventually burst. The result is a sharp reverberating bang. Back then, this never-before-heard noise was quite alarming.

The Chinese figured that if this noise scared them it would scare evil spirits. One particular evil spirit was Nian. This spirit was known to eat crops and people! To protect themselves, the Chinese would use "bursting bamboo" or pao chuk at all special ceremonies such as weddings and celebrations for centuries.

Soon, a Chinese chemist accidentally discovered gunpowder. This chemist was mixing around sulfur, charcoal and potassium nitrate (KNO3) and BANG! This bang was more powerful and louder than ever!

Over time, the Chinese used chemistry to perfect their firecrackers. They also used this knowledge to do more than just scare evil spirits. They used firecrackers and extensions of them---rockets and bombs---to blow away their enemy.

Luckily, many scientists have stayed true to making firecrackers fun! These scientists have found that certain chemicals make the firecrackers colorful. And, potassium chloride (KClO3) was found to be even better than KNO3 as it made the colors deeper and brighter. Example chemicals that make certain colors are strontium to make red, barium to make green, copper to make blue, and sodium to make yellow.

Little Lion Experiment:

How to make safe firecrackers:

Materials:

• Toilet paper or paper towel rolls
• Dry rice or dry beans
• Colorful wrapping paper
• Curling ribbon

Steps:

Cover the cardboard rolls with wrapping paper. Leave about 3 inches of excess paper on each end. Gently twist wrapping paper to close ends. Secure the ends of the wrapping paper with ribbon. Before securing last end, put a few dried beans or rice inside. Shake the roll. It will make noise like a "firecracker."

Why do the Seasons Change?

When does summer actually start? Do you think summer starts as soon as school ends? Or, do you think it starts as soon as the sun is out and burns your skin? The last day of school, sunny days and sunburns are all signs of summer. But, in the northern hemisphere (the top half of the globe), summer does not actually start until June 21st.

To be exact, summer starts at 0148 UT on June 21st, which is 9:48 Eastern Standard Time (our time zone) on June 20th. Yes, that means summer actually starts during the night of the 20th for us. But, June 21st is still the first full day of summer. Known as the summer solstice (sun stands still), June 21st is the longest day of the year.

In the southern hemisphere, below the equator (the line in the middle of the globe that splits the world into two), winter arrives. For them, June 21st will be the shortest day of the year. It also marks the start of winter for them.

Why do the weather and seasons change? To answer this question we have to think about the planet we live on. The Earth takes a yearly trip around the Sun. For part of the year, the Earth's north pole points away from the Sun and part of the time toward it. When the North Pole points toward the Sun, the Sun's rays hit the northern half of the world more directly and it is summer. But when the North Pole is pointed toward the Sun, the South Pole is pointed away. So the Sun's light hits the Earth at a less direct angle, spreading the warmth over a larger area, and it is winter.

Some people think the seasons are caused by how far the Earth is from the Sun. But, the Earth's orbit about the Sun is very close to circular and the distance of the Earth from the Sun only differs by about 3% during the year. Another problem with this hypothesis is we are actually closest to the Sun on about January 2nd, and the farthest on about July 4th. This is the opposite of hot and cold weather in the northern hemisphere. Therefore, the angle at which sunlight hits the Earth is more of a cause of seasonal changes than the Sun's difference from Earth.

Another factor in seasonal changes is the length of days and nights. In the summer, daylight lasts longer and nighttime is shorter. This makes the temperature higher. In winter, the days are shorter and the nights longer. The winter gives the sun little time to warm up the Earth so short winter days do have long, cold nights.

Speaking of winter, the shortest day is the first day of winter. For us in the north, it is around December 21st or 22nd. This day is known as the winter solstice.

Between winter and summer, we have spring. It starts on about March 20th. On this day, day and night time are each 12 hours long. This is called the vernal equinox. It is the first day of spring north of the equator and the first day of autumn in the southern half of the world.

In between summer and winter there is another equinox, called the autumnal equinox. Just like the vernal equinox, day and night each are 12 hours long. But, it is now the first day of autumn north of the equator and the start of spring to the south.

What Is In Sweat?

Now that springtime has finally arrived, so has the Sun. More Sun means higher temperatures and more time to spend outside playing. Oftentimes, Sun, heat and sports equal sweat. I am sure most of you have experienced this but do any of you know why this occurs? Do any of you know what sweat exactly is? If not, read this.

Sweat or perspiration is the fluid produced by sweat glands. Sweat glands are found mainly in the skin of the armpit. But, other areas on the body produce sweat. This would include your forehead, hands and feet.

But, what is it made of? Sweat is a mixture of water, ions, urea, uric acid, amino acid, ammonia, glucose, lactic acid and ascorbic acid. What are all these things? Water is just that---water. Ions include sodium, which is represented by the chemical symbol Na+ and chloride, which is represented as Cl-. These are often thought of as together as salt. They help to make our sweat so sticky and "salty."

These important ions are taken away from the body when they are "sweated out." When an athlete exercises for several hours in the hot sun, they lose lots of sodium and chloride and other types of electrolytes. Electrolytes are any compound that separates into ions when dissolved into water and is able to conduct electricity. They are very important to helping us stay hydrated or with enough water to function. A water loss of as little as three percent hurts our ability to run, walk and think. When we sweat a lot, we lose lot of electrolytes. This is why products such as Gatorade were created. They provide athletes, who sweat a lot during workouts and games, with much needed water and electrolytes.

Okay, so we know what electrolytes are. What about all those other things in sweat? Urea, amino acid and ammonia are products that are made from the break down of protein. Protein is found in foods such as meat, fish, eggs and milk. Proteins serve many roles in the body: they help us grow, help with chemical reactions in the body, help control body processes through hormones, help protect the body against foreign invaders through antibodies, help in maintaining hydration, help maintain they body's acid-base balance, transport substances such as oxygen around the body and also provide us with energy to walk, talk and breathe. Proteins are important!

Glucose or "sugar" provides the body with energy too. Lactic acid is produced when we use up our glucose stores in the muscle. It causes the burning feeling in our muscles when we exercise a lot. Ascorbic acid or vitamin C is found in oranges. It helps with many key body functions.

All these important things are in that sticky fluid that runs down our face when we exercise outside when it is hot.

But, why do we sweat? Sweat helps to regulate the body's temperature. It provides a way to cool the body down. It also gets rid of some of the body's waste products such as lactic acid that the body does not need.

Obviously, sweating is important for the body. It is also important to remember when we are outside sweating away to drink plenty of water and, if needed, sports drinks like Gatorade to replace our lost electrolytes.