How Does Temperature Affect the Cleaning Ability of Soap?

James from Altoona, PA, was helping his older brother wash some dishes in their kitchen sink recently, and he noticed that the dish detergent seemed to rinse off the dishes better with cold water than with hot water. He also observed that the hot water helped make the dish detergent foam more (i.e., produce more soap suds). He wrote in asking: how does the temperature of water affect the cleaning ability of soap? The use of soaps and detergents is part of everyday life (at least it should be!) so let's first discuss what soap is and how it works. You have probably heard the terms soap and detergent used to describe the various products that are used to clean clothes, dishes, hands, cars, or pretty much anything that needs cleaning. While they are very similar, they are slightly different. A detergent is a substance that cleans dirty or soiled surfaces. It is usually made from synthetic ingredients, which means the ingredients are not naturally occurring and are maufactured from different chemicals. Soap is a type of detergent and is usually produced from natural ingredients. Just from looking around your home, you probably have noticed that soaps and detergents are produced in many different physical forms - for example, there are bars, flakes, pellets, liquids and even tablets! Detergents and soaps contain a basic cleaning agent called a surfactant, which stands for surface active agent. Surfactants consist of molecules that attach themselves to the dirt particles of the dirty material that is being cleaned. The dirt particles are pulled out of the dirty material and are then held in the wash water until they are rinsed away. Most detergents contain a synthetic surfactant in addition to other chemicals that are added to improve the detergent's cleaning ability. Other ingredients that are added to detergents include perfumes, coloring agents and germ-killing or antibacterial agents. When it comes to temperature, hot or cold water is acceptable when cleaning with soap. The most important part of cleaning is using the soap or detergent! You need something that will pull the dirt particles from the dirty areas. Water alone will work OK, but water with soap will work even better.

Little Lion Experiment:

Like James above, you may notice that more soap suds are produced when using hot water. The reasoning for this begins with the fact that warmer water evaporates faster than cold water (the warmer water changes from a liquid to a gas faster than cold water). Soap suds or bubbles are formed more easily when the warmer water is evaporating. Colder water evaporates slower so it is harder to make soap suds. With this information, do you think bubbles will last longer in hot or cold water? This experiment will help you determine the answer!

Items Needed

• Two large bowls (or tubs)
• Rubber gloves
• Tablespoon measuring spoon
• Access to cold and hot water (from your faucet is OK)
• Stop watch
• Some type of soap (you can use dish detergent, laundry detergent, hand soap, etc.)

Procedures

1. Fill one bowl with warm water and the other bowl with cold water.
2. With the gloves on, add one tablespoon of your soap to each bowl.
3. Use the tablespoon to mix the soap into each bowl for 30 seconds.
4. After mixing, start the stop watch and observe how long the bubbles remain in each bowl. Did the bubbles last longer in the warmer water or the cold water? Why do you think this is so? With the faster evaporation of the warm water, the bubbles may form more quickly than the cold water but that also means that they will disappear sooner too. The slower evaporation of water means that the bubbles may take longer to form but they will also last longer once formed.

What is in the Air We Breathe?

Laura from Hollidaysburg, PA, was recently helping her parents clean her home, and she noticed how much dust there was on the tables, in the air, and coming from the couches! She wrote in asking: Where does dust come from and what happens to it when we breathe it in? About 21% of the air we breathe is actually oxygen, while the remaining air consists of other gases (e.g., nitrogen, argon, carbon dioxide). However, the air also consists of dust, tiny animals, and other stuff! Dust is defined as dry, solid particles that are less than 0.0625 millimeter in diameter, which is smaller than all grains of sand! Most dust is composed of mineral matter that originated from bare soil, plowed fields, river flood plains, and floors of desert basins. Dust also comes from ocean spray, smoke and ash produced by fires, decaying organic materials, and volcanic eruptions. The wind actually lifts up the dust particles and easily carries them long distances around the earth! The dust in your home can also be made up of dust, pollen, mold, sand, skin flakes, and pet dandruff. These air particles are actually the most common causes of allergies or asthma. Humans and animals can also act as carriers of dust and air particles because the air particles can cling to their skin or clothes. When you breathe in, you are also breathing in dust or air particles. Some of these air particles will get caught in your nose hairs, some will get caught in mucus in your airways, and some will make it into your lungs. However, don't worry too much about this, because most of what you breathe in will cling to the hairs on the inside of your nose. These hairs act as a filter, which works to trap the inhaled air particles inside your nose to keep them from traveling into your respiratory system. The hairs usually trap particles that are less than 5 nanometers in size (that is approximately 0.000005 mm!). Aside from the many nuisances of dust around your home, dust actually contributes to some beautiful sunsets and sunrises. That's right, dust is what makes sunsets and sunrises so pretty! The intense red and orange colors of the sky at sunset and sunrise are mainly caused by the scattering, or reflection, of sunlight off air and dust particles. So the next time you are cleaning your house or enjoying a beautiful sunset or sunrise, think of the dust that is contributing to these everyday events.

Little Lion Experiment:

This experiment will allow you to observe the types of air particles you breathe regularly.

Items Needed

• 6 index cards
• Scissors
• A pen
• 6 pieces of string
• tape (scotch, masking, duct, or packing tape is good)
• A magnifying glass
• A ruler

Procedures

1. Cut squares into the center of each index card. Try to make all the squares the same size (e.g., about 2'' by 3'').
2. Choose 6 locations within your home that you want to hang the air particle collectors. Some places to hang your air particle collector include: above your bed, on the inside or outside of a window, near a heating vent or air conditioner, above the cooking stove, on a wall near the floor or ceiling, on your main entry door, and under a tree.
3. Write down the locations on the index cards so that each index card has a different location on it
4. Write the starting date on each index card
5. Cover the window on the index card with the tape so that the stick side up or out.
6. Attach string to each index card, and then hang the cards at the appropriate locations.
7. Wait a few days and then take the index cards down without touching the tape. Make sure to note the date. Which location had the most air particles collected? Were these locations inside or outside? Why do you think this is so? Think about where air is moving, and where the air particles could be coming from. Use your magnifying glass to examine the air particles up close. Can you recognize any common air particles?

Why Do We Get Sunburns?

Have you ever forgotten to put on sunscreen, then regretted it the next day? Many of us know what sunburns look like, but do you know why we get them? Let's start with some background information on how our skin responds to light. Cells called melanocytes in the inner part of your skin produce the pigment melanin, which is what gives color to our skin. Believe it or not, we have about 1000 to over 2000 of these cells per square millimeter of skin! If you have dark skin, that means that your melanocytes are programmed to make a lot of melanin all the time. If you have lighter skin, then you have the same number of melanocytes, but they don't produce as much melanin. If you are albino, then your melanocytes cannot do their job because they are lacking an enzyme (a piece of cellular machinery) which is needed to make melanin. On most days, we do not get exposed to enough sunlight to cause us to develop a suntan. However, a nice day spent at the beach is much different. The darker your skin is, the more light you can withstand without having to boost your melanin production. When your body senses that you need more melanin to protect you against harmful UV rays (UV stands for ultraviolet), your melanocytes kick into high gear and you get a suntan. However, if you stay outside for too long, especially without sunscreen, then your body can't make melanin fast enough to keep up with the amount of UV exposure. This is what causes a sunburn. A sunburn can be thought of as a "clean-up crew" of various blood cells being sent to repair the damaged area. This increased blood flow is what causes sunburns to appear red and feel warm to the touch. Starting to sound a bit like a sunburn? There's one thing missing: why does sunburned skin tend to peel? Your body does its best to repair the UV damage, but if the damage is too great, then the unrepaired cells will simply shed or flake off to make room for new healthy cells to replace them, which allows the sunburn to heal. You may have heard about the relationship between sunburns and skin cancer. Even though the "clean-up crew" and the skin cells themselves usually undo the harmful effects of UV, they may not always do a perfect job. This would allow damaged cells to stay in the skin. Most sunburns will not lead to cancer, but a tiny fraction of them can if they damage a cell's ability to stop dividing. This is why it is so important to wear sunscreen in order to avoid over-exposure to UV light. There are two types of sunscreens: those that reflect UV light (like tiny mirrors) and those that absorb it like melanin does. Everyone gains extra protection from wearing sunscreen, but if you are fair-skinned or albino, it is especially important that you wear it. Remember to put it on around 30 minutes before you go outside so that it has time to stick to your skin. Otherwise, it will rub off on the grass or wash off in the water. [Safety note: some people (especially those with sensitive skin) have allergies to PABA, a chemical in some sunscreens. So if you have sensitive skin, you may want to consider buying a PABA-free sunscreen]. For more information, visit http://travel.howstuffworks.com/sunscreen.htm

Little Lion Experiment:

While UV light is harmful in some respects; we need it to stay healthy! This is because our bodies need about 10 to 15 minutes of daily UV exposure to make vitamin D. In fact, many reactions are activated by light (various kinds of light, not just UV). To see how important light is for living things to survive, obtain two small planter pots. Plant about 5 evenly-spaced seeds in each pot. If you cannot purchase seeds at your local hardware or gardening store, you could use seeds from a fresh tomato. Place one pot in front of a sunny window and place the other pot in a dark area (a cabinet would do, with your parents' permission). Remember to water the plants every few days (specific instructions can be found on the seed packet). Check on the plants over the next couple of weeks to compare the seedlings in the light versus those in the dark.

How Does a Pencil Eraser Work?

The pencil eraser works based on the friction developed between the eraser and the paper. Friction is what causes your hands to heat up when you rub them together. When you rub two objects the roughness of their surfaces contact each other and rub against each other causing friction. A simple pencil is made of a combination of wood and finely ground graphite and clay, mixed with water and pressed together at high temperatures into thin sticks or rods. Graphite is a mineral composed of an element called carbon, and it is black in color. There are also mechanical pencils that need rods of graphite to function like a pencil. You may have heard that pencils are made of lead, but that is actually a misunderstanding that is based on the initial thoughts of those that first discovered graphite - they believed it to be lead, which was not the case at all. However, many still refer to graphite in pencils as lead. Graphite particles are arranged in layers or sheets. A pencil mark consists of graphite particles that have peeled off from the pencil point onto the paper. These particles have an angular, gritty look to them when viewed under a microscope. When the pencil is used on a sheet of paper, the graphite particles lie slightly below the surface of the paper, interlocked between its fibers. A single rub using an eraser sufficiently soft to reach between the fibers will pick up most of the graphite particles. Looking at the eraser you can see undamaged graphite pieces sticking to the surface. An effective erasing material scratches the paper surface, producing the familiar small spindles of rubber or eraser material, which wrap up the graphite particles. When you look at these under an optical microscope at 200 times magnification (200x), these look like roly-poly puddings studded with graphite raisins.

Little Lion Experiment:

Erasers come in a variety of colors: white, pink and gray are some of them. Sometimes the color difference is because of a dye or because the eraser is made of a different type of rubber. Go around your house and see how many types of different erasers and pencils you have. For example, compare number 2 pencils with a number 3 pencil. Also, if someone in your home has a mechanical pencil, you can purchase different types of pencil leads (like hard black or soft) or they might have different leads you can use. The bright-colored erasers (like purple and yellow) are usually white erasers in disguise! You can also use erasable pen as a pencil type. See which one of these works best with different types of pencils and ink. Can you erase the ink with a pink or white eraser? Is there one eraser that works for all lead types? Knowing what you know about how erasers work, why do you think certain erasers do not work with other types of pencil lead and ink?

Why Does Ice Float?

It is almost officially summer! And that means plenty of sunshine and hot temperatures. With all the sun and heat, you will likely be drinking more water to keep hydrated. Most people prefer their water to be "ice cold", which just means there is ice in the glass to keep it cold. But, you may have noticed that ice doesn't just sink to the bottom of the glass - have you ever wondered why? This month we will explore that very question! The meaning behind this mystery lies in the different properties of solid and liquid water. Nearly every solid, if placed in its liquid form, will sink to the bottom. Luckily for us, the properties of water are different. Unlike most other substances on Earth, the solid form of water floats on the liquid form. This is caused by the change in density, which is defined as the amount of mass in a volume. With the exception of water, most substances on Earth become denser as they become colder. The solid ice will float because its density is lower than that of water. It is about 9% less dense than water. The denser water sinks to the bottom forcing the less dense ice to the surface. What makes water molecules different from other molecules is that they attract each other in an organized fashion. As the water cools, the molecules begin to bind to each other, forming a hexagonal pattern (shape that has six sides). Water is at its densest point at 4 degrees C. After that point, the water molecules move very slowly and attract to each other. In most substances, the molecules are more tightly packed together in solid form. But in ice, the hexagonal pattern of the attracting water molecules leaves empty spaces. This is why water expands when making ice cubes. The empty space between the hexagonal shapes makes the solid form less dense than the liquid form so that it floats to the top. Thanks to this oddity of physics, the water in our oceans and seas remain in liquid state. If the solid form of ice happened to be denser than water, the ice would sink to the bottom. If this happened, the ice on the bottom would begin to freeze up toward the surface. Eventually, nearly all the water on Earth would become solid ice and never melt. Luckily, ice floats and remains on the surface so that the water underneath remains in liquid form.

Little Lion Experiment:

This experiment will demonstrate that ice does float in most liquids, but you will also test other solid materials to see if they float, too.

Items Needed

• 4 ice cubes
• 4 small rocks
• 4 small magnets
• 4 quarters
• 4 glasses
• 4 different liquids (e.g., water, soda pop, salt water, and milk)

Procedures

1. Put each liquid in its own glass.
2. Drop one of each solid material (i.e., ice cube, small rock, small magnet, quarter) into each glass.
3. Observe what happens. Did any of the materials sink to the bottom or float to the top of all the glasses? Did some sink to the bottom of one glass but float to the top of another glass? What can you conclude about the solid materials? What can you conclude about different liquids used? Keep trying different solid materials and different liquids to see how they compare!

What Are Allergies?

A-choo! With all the flowers blooming, it is no wonder that hay fever is upon us - that is, it is allergy season! Kaylee from Altoona, PA, who suffers from seasonal allergies writes in to ask about allergies. We are all familiar with the coughing and sneezing, but what exactly are allergies and what causes them? Every day, our bodies are in constant contact with potential threats. These include pathogens (harmful microorganisms), pollution, and a host of other dangers. However, most of the time, we aren't even aware that anything nasty has entered our bodies. How are we able to combat these invaders so effectively? We have our immune system to thank. Immune cells called lymphocytes (pronounced lim-fo-sites) patrol all parts of the body looking for foreign molecules and microorganisms (tiny living things, like bacteria). Each lymphocyte is programmed to recognize a specific pathogen. Anything which is not part of our body is classified as "non-self" while every one of our own cells is termed "self." In short, the role of the immune system is to attack and destroy any cells it finds that are "non-self." We also have sensors in our bodies which can detect the presence of harmful chemicals. Have you ever walked by a car and coughed or sneezed as you smelled the exhaust? This is because you have sensors in your nose, throat, and lungs that tell your brain that you have inhaled dangerous fumes, which you need to get rid of right away. So, your body sends the signal to cough and sneeze until you push out all of the fumes. This signal is sent by a chemical messenger called histamine. If you have allergies, or know someone who does, then you might agree that the symptoms of allergies are kind of like a huge overreaction to the car fumes, except without the car! People with allergies react as if they have inhaled something toxic when in fact they have just inhaled normal everyday things like pollen and dust that are not harmful (these everyday substances are called allergens). This occurs because some of their lymphocytes are programmed to recognize the allergen as a harmful substance even though it is not. So, when the lymphocytes find an allergen floating around in your body, they trigger histamine to be released which causes the common allergic symptoms such as watery eyes, runny nose, sneezing and coughing (these are all ways to flush out the allergen). Histamine also triggers local swelling near the pathogen or allergen, and so it can cause narrowing of the airways (nose and throat) when you inhale pollen or dust in order to prevent more of the allergen from entering the lungs. Unfortunately, that makes it harder for the person to breathe. Here's an interesting fact: histamine is also responsible for asthma - can you see the connection? So how can we treat allergies? The primary method to prevent allergic symptoms is to treat the person with antihistamines, which have been used since the 1930s to control allergies. The medicine does not affect the lymphocytes, but rather it just prevents histamine from triggering its bothersome symptoms.

Little Lion Experiment:

This experiment will demonstrate how allergens or pathogens may stick to the lining of your nose or throat to cause sneezing and coughing.

Items Needed

• An empty toilet paper roll
• Running water from your sink
• Black Pepper
• Salt
• Confectioner's Sugar
• Jimmies or sprinkles

Procedures

1. Run water over the inner surface of the roll until it is wet but not soggy.
2. Hold the tube sideways in one hand over a sink (so as not to make a mess) and carefully place the pepper on the inside of the tube
3. Rotate the tube until it is coated with the pepper.
4. Repeat steps 2 and 3 with the salt, sugar, and jimmies

Did all of the substance stick? If the substance does not stick, then that is a pretty good indication that it is large enough that it would not stick to the lining of your nose or throat. If it sticks, then it is probably something that would get trapped in your airways if you were to inhale it. Now, slowly turn the tube until it is vertical. To simulate coughing, quickly shake the tube or bang it against the inside of your sink. See which kinds of substances come out the most easily. To simulate sneezing, blow air through the tube and see what comes out in your sink. The body also uses mucus in your airways to help carry foreign molecules out (like the sea carries shells to the shore). Pour a small amount of oil into the tube and see if it takes out some of the remaining particles.

What is the Water Cycle?

Cole from State College, PA, wrote in to ask if the Spring-time saying “April showers bring May flowers” is true. The saying points to the theory that the large amount of rain observed at this time of year is thought to assist in the growth of plants and flowers that generally bloom in May. However, flowers actually bloom at different times during the year depending on their location, so timing of rainfall that aids in the health and growth of flowers is different depending on that location. Too much rain can also negatively affect the plants by making them more susceptible to diseases or killing the roots. This question brings up another good question, though - where do “April showers” come from? To answer that, we’ll need to learn about the water cycle.

The water cycle is a term used to describe the continuous movement of water in and around the Earth. About 70% of our Earth is covered by water, which amounts to approximately 333 million cubic miles! So that’s a lot of water in constant operation – but how is it in a constant cycle?

Two major components of the water cycle are evaporation and condensation. Evaporation occurs when a substance goes from the liquid to the gaseous state, and condensation occurs when a substance goes from a gaseous to a liquid state. These processes happen on Earth with the help of the sun. The sun heats the surface of water causing it to evaporate into water vapor (gaseous water), which rises into the atmosphere. This water vapor then cools and becomes clouds, which eventually condense into water droplets. Depending on the temperature of the atmosphere, the water then precipitates (falls back to the Earth’s surface) as rain, sleet, hail or snow. Some of this precipitation falls on trees or other plants and can evaporate again into the atmosphere. The precipitation can also continue to the ground, and now the water is considered runoff water. This runoff water can then get into the ground and accumulate where it is eventually stored in aquifers, which are large, natural storage tanks of groundwater that can be used later if needed. The runoff water can also form or add to lakes and streams, which can also then freeze into snow caps or glaciers. Water that falls to the ground and stays in the soil ends up evaporating and returning back to the atmosphere – you can see how this is a continuous cycle! The water in aquifers, though, can accumulate there for thousands of years. Aquifers are actually our major sources of drinking water.

So consider the long journey water has taken the next time it rains, snows, hails or sleets. Maybe it end up as your drinking water or maybe it will end up in your local water reservoirs. Perhaps, it will just evaporate back into the atmosphere to come back to the Earth’s surface as rain another day.

Little Lion Experiment
This experiment will allow you to create a small-scale model of the water cycle using common items found around your house. You will need: plastic wrap, a large bowl (preferably one that is clear), a weight (a paperweight will work), small container (a clean, empty yogurt cup works well), a rubberband or piece of string, tap water, paper and pencil. You will also need access to sunlight.

Steps: 1) Place the small container in the middle of the large, clear bowl so the opening of the small container is up. 2) Fill the bowl with some water (at most half full) but be careful not to fill the small container inside. 3) Cover the bowl with plastic wrap. 4) Fasten the plastic wrap around the bowl’s rim with the rubberband or string. 5) Put a weight on top of the plastic wrap in the center. 6) Put the demonstration on a window sill or somewhere that it will be in contact with the sun. 7) Record your observations of the experiment every 10 minutes on your paper (you should conduct this experiment for at least an hour).

What did you observe? Hopefully you saw that the heat of the sun evaporates the water, which rises, condenses on the cool plastic, and falls into the small container similar to how rain falls. Now that you know how to make your own model of the water cycle, change some of your materials in the experiment. For example, use salt water instead of tap water. Or, you could use ice water (a mixture of water and ice chips) instead of tap water. Were you still able to observe the water cycle?