Archive | March 2016

Understanding Sound

images (31)Hearing is one of the most important senses of the human body. We use it everyday in our daily lives, and we hear as much or more than we see, feel, taste, and smell. What do we exactly hear? The answer to that question is sound. What exactly is sound though, and how is it created? Sound is a series of vibrations that travel through air or another platform and heard when it reaches the ear of a person or animal. In more simpler terms, sound is a form of energy that spreads out through space. What is the source of all sound? In one word, vibration.

A major facet to understanding this concept is pitch. What exactly is pitch? Pitch is what refers to the frequency of the sound. A high pitched sound has a high vibration frequency, while a low pitched sound has a low vibration frequency. The pitch range of frequency is from about twenty hertz to twenty-thousand hertz. The more we age, our hearing range goes down or shrinks, more specifically at the end of high frequency.

Sound waves with frequencies below twenty hertz are called infrasonic. As for sound waves with frequencies above twenty-thousand hertz are called ultrasonic. Unfortunately for humans, the hearing of infrasonic and ultrasonic are unavailable. However dogs and bats can hear way better than humans. Dogs can listen to frequencies of over forty-thousand hertz and bats can hear over frequencies of over one hundred thousand hertz.

There are two more very important topics to be discussed when it comes to comprehending sound. These two include compressions and rarefactions. Compression is the pulse of compressed air. Rarefaction is the pulse of low-pressure air. An example of both of these happening in the real world is when someone both opens and closes a door. When someone opens a door, a compressions goes throughout the room. As for when someone closes a door, a rarefaction travels throughout the room. This is why when someone closes a door, a curtain moves. For all wave motion, it is not the surface and or the medium that travels across the room, but the pulse that does. Proof for this being true is when the curtain moves when someone closes a door.

In an overall summary, sound is a very important concept that needs to be understood. The main points include that sound is created by vibrations. It travels through air or another platform that can be heard by someone. Basically, you can’t hear sound in an empty space such as outer space. Important concepts to be noted and understood regarding sound are what pitch is, compressions, and rarefactions.

 

This entry was posted on March 21, 2016, in Education.

The History and the Types of Automotive Gasolines

download (43)The automotive industries were dated back to the early 19th centuries, and it has prospered until right now in our communities. Most cars in the 19th century uses simple types of a combustion engine that laid the foundation for the development of the engine we see today. However, the fuel sources of both engines that are used to propel the cars remain the same (as long as they are used to powered an internal combustion engine). In today’s society, we mainly see cars that have a combustion engine uses pure gasoline. However, they are many types of gasoline from leaded to unleaded fuel and from octane ratings rated at 87, 89, and 91.

The invention of pure gasoline (not to be confused with Diesel) dated back to the Gilded age with the distillation of oil to kerosene. At first, there was no used for gasoline because cars were not invented and most transportation uses steam as its sources of energy. Therefore, it was discarded. Gasoline finally became a valuable commodity, with the introduction of Henry Ford’s affordable car in the 1920s known as the “Model T.” As time progresses, we saw an improvement in refining gasoline and creating a purer fuel that would make cars go faster. Increasing the purity of gasoline meant that the octane level must be increased, so lead was added to improve engine performance. The Octane rating tells us how much air and fuel mixture can be compressed before being ignited. The higher the octane, the more compression the fuel can withstand before detonating. However, leaded fuel was bad for the environment, so there was another development that leads to unleaded fuel.

Unleaded gasoline was introduced in the 1970s when health problems from lead increased. Unleaded gasoline also guaranteed the conditions of important engine parts like the intake valves and fuel injectors; that would help improve fuel economy and performance. In today’s gas filling stations, we will see that the stations are required to carry Unleaded benzene gas. The octane rating of the gas we commonly see is 87, 89, and 91. The most standard unleaded fuel are rated at 87 octanes. It was designed for most normal cars that doesn’t require much power, but it is still powerful for small cars on the road today. 89 octane stands in a higher tier than 87, but still could not compete with 91. It has a faster ignition capability that is suited for some small sports cars, like those made in Japan and America.

The King of the Hill that beats all consumer-grade fuel is 91. Octane 91 is the premium grade unleaded fuel that meet the demands of some of the today’s most advanced engines. It has an octane level of 93, but it is blended with an octane level of 91. We can see that the most demanding European cars and supercars are required to refuel with this type of fuel, in order to achieve full performance.

In conclusion, the automotive industry could not live without the use of gasoline that is distilled from crude oil. Even though the innovations of electric power have progressed far, it is still expensive for most people. Gasoline is still considered the primary fuel source for the automobile.

Static Guard

images (30)Static Guard and How It Works

Static electricity is a kind of electricity that stays in one place. Static can build up on things that do not conduct electricity very well such as rubber and plastics. Coming in contact with static by providing a discharge of current from your body can be very uncomfortable. There are products which can eliminate or reduce static electricity in order to avoid a nasty shock. The product Static Guard is a chemical method used to eliminate static electricity. The spray is made up of a conducting polymer (plastic) and a solvent made from deionized water and alcohol. You spray the product on a surface like a dress or a sweater, and when it evaporates, it leaves behind a conducting “skin” on the surface of the object that prevents static build up. As the conducting layer is left on the surface of an object that has been sprayed, static electricity cannot build up on the object and, therefore, you do not have to worry about shocking yourself. Static electricity has no way to release the energy that builds up so it does not move until it is touched by something which can conduct the electricity. An example of this would be if you built up static electricity with your socks and then touched a doorknob. The static has nowhere to go until you touch the door knob which releases the static, causing a static shock. This example also illustrates an important point that metals, like those composing a doorknob, are good conductors of electricity.

Another example supposed solution to static shock is this: Sometimes cars drive with a rubber strip dangling out of the back of their car, mostly during the winter and fall. Some people believe that the rubber touching the ground will release the static electricity in the car. This has actually been proven to be completely wrong. This precaution is unnecessary because the car’s tires are responsible for transmitting static from the car to the ground and back again.

What makes the spray special is that there are components in the spray that neutralize your clothes to keep them from sticking to your legs and shocking you. This product is especially popular during the winter when people are constantly getting shocked by static electricity. This is because of all the layers of clothes a person wears. When the clothes rub together, it causes friction, which causes static electricity in return. However, if products such as these are not properly used, they can become dangerous to people if they are exposed to it for long periods of time. The product is flammable, and should not be placed near open flames or in hot spaces. The product can also cause trouble breathing, and irritation of the mucus membrane, which has lead to difficulty breathing. There have been no reported deaths attributed to this product, but the spray has been known, in rare cases, to cause liver damage in both humans and rats.

Static guard is a wonderful product that has been keeping our clothes static and cling free for years, but be warned, the product can cause serious side effects if used too frequently.

Energy in Chemical Reactions

images (29)A chemical reaction happens when two different elements or substances interact to form a new substance with a different chemical composition. Along with every chemical reaction, comes a change in energy, where that energy is either gained or lost. Energy is the capacity of an object to do work or supply heat. Within the chemical bonds of substances there is chemical potential energy. The way atoms are arranged within a substance determines the amount of chemical potential energy a substance has. When a substance undergoes a chemical change, its energy changes. This change in energy can be observed in different ways. Oftentimes, a change in energy also results in a change of heat, with the heat flowing from a warmer object to a cooler one. Sometimes a change of energy, during chemical changes, causes a release of light or sound as well as well. For example the chemicals in fireworks produce light and sound.

A chemical change that gains energy is called an endothermic reaction. An endothermic reaction happens when an object absorbs heat from its surroundings during a chemical reaction. An example of an endothermic reaction would be melting ice. The ice absorbs heat, causing it to liquefy and taking away heat and energy from its surroundings.

There are also chemical reactions that release energy and heat, called exothermic reactions. Heat flows from the object into its surroundings, the opposite of an endothermic reaction. An example of an exothermic reaction is taking two substances, such as water and calcium chloride, and mixing them together, resulting in them releasing heat into the surrounding area.

During chemical reactions, though energy within an object is lost or gained, no new energy is actually created or destroyed. This is the law of conservation of energy. This means that if, during a reaction, an object loses a certain amount of energy or heat, its surroundings’ energy or heat will increase by that amount and vice versa.

It is important to know about energy within chemical reactions, because how energy changes during a chemical change, allows us to learn important things about the reaction that has taken place. A change in heat or energy allows us to know when a chemical change has taken place, whether or not it is endothermic or exothermic, and how much energy has been lost or gained within an object, all important when trying to understand how different chemicals react with one another. Changes in heat are also utilized in daily life. For example, when you burn wood, it releases heat, used to warm or light a space.

Understanding how different reactions release heat can allow us to further utilize energy changes in this way.

My name is Hannah. I am a freshman in high school, at a small school in Los Angeles. This is my final article for my chemistry class. My favorite subject on school is science.