Dialogue: Between Teacher and Students (Scientific Method)

The scientific method is a systematic means of exploring and explaining the world around us. The exact number of steps to the scientific method depends on how you break up the steps, but here is an overview of the basics:

    1. Make observations.
    2. Propose a hypothesis.
    3. Design and perform an experiment to test the hypothesis.
    4. Analyze your data to determine whether to accept or reject the hypothesis.
    5. If necessary, propose and test a new hypothesis.

Lets to read example dialogue!

 "Chemistry of fireworks"

After mark the attendance card, Mr. yus standing in front of the class, fix his glasses and smilling at us.

“How about the task last week? Do you know about firework?”

“ We know sir,” we answer with compact.

“Is it pretty?” Mr yus convincing

“Of course sir”

“Oke ,now reed your note book!”  Mr. Yus instruct us. We are glance each other, there is no one who reed the book. Including me. Because I don’t understand any more. 

“Do you know sam?” Mr yus turned to sam. “Read your note in your book please?”

“Fireworks are made from various chemicals. The colors produced are a complicated combination of various chemicals. Commonly used elements for the manufacture of fireworks include magnesium, sodium, franium, lithium, boron, potassium, calcium and various oxidizers.”

Mr. yus listen sam’s explanation.

“Next, who want to reed?” we are just silent with confusing.  Mr. yus laughing see our face one by one, “Fireworks are found in China to frighten evil spirits, as the development of other invention of gunpowder. Celebrations and festivals such as Lunar New Year and Moon Festival in mid autumn are still equipped with fireworks. China is the world's largest producer and exporter of fireworks. Do you understand ?”

We just shaking our head.

“Ok. For easier to explain, we can see this video first about firework. Fireworks generate three very noticeable forms of energy: a tremendous release of sound, bright light, and heat. The tremendous booms heard at ground level are the result of the rapid release of energy into the air, causing the air to expand faster than the speed of sound. This produces a shock wave, a sonic boom”.

“Do you know where is firework come from?” Mr. Yus see our face one by one again. We are shaking our head again.

“The colors are produced by heating metal salts, such as calcium chloride or sodium nitrate, that emit characteristic colors. The atoms of each element absorb energy and release it as light of specific colors. The energy absorbed by an atom rearranges its electrons from their lowest-energy state, called the ground state, up to a higher-energy state, called an excited state. The excess energy of the excited state is emitted as light, as the electrons descend to lower-energy states, and ultimately, the ground state. The amount of energy emitted is characteristic of the element, and the amount of energy determines the color of the light emitted. For example, when sodium nitrate is heated, the electrons of the sodium atoms absorb heat energy and become excited. This high-energy excited state does not last for long, and the excited electrons of the sodium atom quickly release their energy, about 200 kJ/mol, which is the energy of yellow light”. Our hand write the material as long as Mr. Yus explained, it feel like never end. We are whispering each other.

“Is there any question?” I and sam rise our hand. “ Ok Bani, what do you want to ask?” Mr. Yus staring me.

“How do fireworks get red colour, Sir?”

“The red color is produced by Strontium metal. Any else?”

“If it’s orange, green and blue?” Sam raised his hand.

“The orange color is produced by Calcium metal. The green color is produced by Barium metal. The blue color is produced by copper metal” Mr. Yus answer.

“The sights and sounds of each explosion are the result of several chemical reactions – oxidations and reductions – taking place within the firework as it ascends into the sky. Oxidizers produce the oxygen gas required to burn the mixture of reducing agents and to excite the atoms of the light-emitting compounds. Various oxidizers are used in both the black powder and the stars. The most commonly used oxidizers are nitrates, chlorates, and perchlorates. The reducing agents, sulfur and carbon, combine with the oxygen from the oxidizers to produce the energy of the explosion”.

“The most commonly used oxidizers are nitrates, the major component of black powder. Nitrates are composed of nitrate ions (NO3-) with metal ions. The most common oxidizer is potassium nitrate, which decomposes to potassium oxide, nitrogen gas, and oxygen gas.

2 KNO₃ -------> K₂O + N₂ + 2.5 O₂

When reacting, nitrates release two of their three oxygen atoms. Because the oxidation does not result in the release of all available oxygen, the reaction is not as vigorous as that of other oxidizers and is more controlled. This is why nitrates are used as the major component of black powder. In fireworks their main purpose is to provide the initial thrust to power the package into the sky and to ignite each bundle of stars. Nitrates are usually not used in star explosions, because reactions of nitrates do not produce a temperature high enough to energize many of the more colorful metal salts”.

“In the 1830s Italian fireworks makers found a group of more explosive oxidizers, which produced temperatures of 1700 to 2000°C and made possible the creation of much more intense colors. These oxidizers are the chlorates, which contain the chlorate ion (ClO3-), and they give up all their oxygen upon reaction.

2KCLO₃ --------> 2 KCL + 3 O₂ 

 This results in a much more intense and spectacular reaction”.

A half an hour,  the time is past. Mr. Yus staring at us with enthusiastic.

“ Are you understand?” Mr. yus shows the question. Most of the student say “ Done sir” some of the student say “no sir”

“Ok, who want to explain again, about firework?” Mr. yus give a chance to us.

“ Bani, you can star it” with confident I standing in front of the class.

Mr. yus say “ Thank you Bani, you want to explain again about firework to your frends” .

Mr. yus sit down and listen carefully mine explanation.