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Course: Exploratorium > Unit 3
Lesson 1: Chemistry introductionChemistry Introduction
Do you have chemistry? Chemistry and chemical reactions can be electric or explosive, sweet or sour, powerful or perplexing. This intriguing area of science involves mixing molecules, creating compounds, stirring solutions, building bonds, and energetic electrons.
Chemistry is about matter—its properties, its composition, and the changes it undergoes in different circumstances. Matter can exist as a solid, liquid, gas or plasma; it can be a pure substance or a mixture. Chemists also study energy in its widely varied forms, like kinetic energy, potential energy, heat energy, light energy, electrical energy, and mechanical energy.
When onions make you cry or batteries light up your flashlight, that’s chemistry. These hands-on activities let you explore some of the chemical reactions and phenomena that surround you every day.
Want to join the conversation?
Why do onions make you cry?(8 votes)
When you cut an onion, it releases a gas called, ready for this, Propanethiol S-oxide. When mixed with certain enzymes in the onion, it creates a sulfur gas. These gases then get to your eyes and create a mild acid which irritates the eyes.
Normally, your body would signal you to close your eyes. This, of course, is not a good idea if you are cutting an onion. The next best thing your eyes can do is to make tears to protect the eyes. Rubbing your eyes is a bad idea, since your hands are likely full of the tear making onion juice. So how do you keep from tearing up? There are many theories out there. I've heard some have had luck burning a candle near the chopping site. (Don't try that without an adult.) Wearing safety goggles, however, should reduce the tears every time.
Source: http://www.sciencebob.com/questions/q-onion_tears.php(4 votes)
what
ok so what if chemistry was never invented and technollogy was down what about that.(2 votes)
Since chemistry is the study of matter - what it is, and how different types of matter interact - NOTHING that was ever invented could have existed without it.
Even before chemistry classes were developed, people were studying the world around them and trying to use available resources to make their lives better. Stone age people used certain types of rocks (with specific properties) to make tools. The discovery of alloys like bronze and brass allowed for the development of sturdier tools and weapons. The use of iron (and the subsequent development of modern steel) allowed people to create harder materials that could withstand even greater mechanical stress, leading to even better weaponry as well as factory machines, ushering in the industrial era.
But you asked about technology. The bits and pieces in your cell phone, for instance, are made of mixtures with specific compositions. What branch of science discovered those mixtures? Chemistry! What provides the power for your cell phone? A battery, which produces an electrical current using a specific chemical reaction. When it comes down to it, without chemistry, your technology wouldn't exist. In my opinion, that makes chemistry superior.(2 votes)
i know that biology and chemistry arent the same but
how much do they have in commun?(2 votes)
They're both science. Biology is made up of chemistry. Chemistry is the study of matter, Biology is the study of life and existence, hence a spin off of chemistry.(1 vote)
- Why do onions make people cry? :'( .... :)(1 vote)
When you cut an onion, it releases a gas called, Propanethiol S-oxide. When mixed with certain enzymes in the onion, it creates a sulfuric gas. These gases then get to your eyes and create an acid which irritates the eyes.(2 votes)
Thank for the lesson, i can ensure you, your effort is not being wasted.Mr Sal...God blessed you!!!!1(1 vote)
How can you identify whether or not an object is a pure substance? For example I know that crushed ice is a pure substance, because it has the same properties in every sample, but would seawater be considered a pure substance? Wouldn't every have the same composition if you took it from the same sea?(1 vote)
How could this happen to me.
I don't want this to happen to me.
It sucks(1 vote)- How do amino acid sulfoxides contribute to the gas that makes your eyes water when you cut an onion?(1 vote)
Lachrymatory-factor synthase is released into the air when onion's are cut and the synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid. The unstable sulfenic acid then rearranges itself into syn-ropanethial-S-oxide and finally the Syn-propanethial-S-oxide is released into the air and comes in contact with your eyes. The lachrymal glands become irritated and in turn tears are produced.(1 vote)
- how to study for chemistry?(1 vote)
Is there chemicals in our bodies?(1 vote)