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¨  What is the importance of chemistry to housewives?
¨  Why, after evaporation, is my sample less heavy than before?
¨  What is the importance of chemistry?
¨  Do different kinds of fruit conduct different amounts of electricity?
¨  What is the standardized composition of air in chemistry?

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What is the importance of chemistry for housewives?

ANSWER from Stephanie Wong 19 March 2007:
There are many chemicals in the home which people may come in contact with.  While usually there are labels that are instructional to how they are used and how accidents are to be dealt with, knowing a bit of chemistry could potentially help.  Whether it is cleaning or cooking, it would be good to know about acids and bases, as neutralizing a spill or decreasing the acidity of a meal is something that one might do.  Inside the house, sometimes there is a buildup of dangerous gases or the air circulation is bad.  Diffusion, a concept used in chemistry, would give an insight to the problem.  For a gardener, the knowledge of fertilizers can improve planting.  For example, the addition of nitrogen, potassium and phosphorous can make plants grow either more leaves, flowers or roots.  Just the being scientifically aware of the chemicals around you makes one prepared and safe about the usage of chemicals.  Chemistry is all around in your life and we rarely think about it.  It is something that all people should be aware of.

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I had an experiment where I was separating a mixture iodine, salt, and sand.  After removing the iodine with heat, I weighed the mixture.  When the mixture was warm, its weight was more than before removing the iodine.  I couldn't get a legitimate answer from my professors why that is.  I would greatly appreciate a scientific explanation.

ANSWER from Stephanie Wong on 10 February 2007:
I think that you might have made an error in your measurements, either the initial or the final weight of the mixture.  By heating the mixture, I assume you meant you heated an open mixture to a high enough b.p. so that the iodine (is it pure elemental iodine?) evaporated into the air.  This you did not explain clearly and is something you need to describe in a precise manner while doing a scientific experiment.  Also, did the iodine react with the salt?  If you are sure that nothing in the surroundings of the mixture reacted with the iodine-salt mixture to make it solid (making the iodine appear to go away but actually precipitating as something else in your container that you did not notice), then by conservation of mass, it's not possible to have a heavier final weight.  Unless there has been a chemical change thereby increasing the mass in the container, I do not see how your mixture could be heavier than before, especially since you appear to have evaporated off the liquid.

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What is the importance of chemistry?

ANSWER from Stephanie Wong on 14 August 2006:
Chemistry is integral in everything in the universe, for almost everything in the world exists because of chemical bonds.  The human body is made up of chemicals.  The chemical reactions that happen in your body allow you to live.  The food you eat changes from chemical potential energy in the digestive tract into energy your body can use to stay alive.  Chemistry is the study of chemical bonds and since chemical bonds are found in every sort of daily function in life, it is important to know more about it.  A chemist can improve our lives by studying how chemical processes work in the body, making new materials, designing ways to reduce pollution in the use of fossil fuels, design clean energy sources, make better electronics, studying how solar radiation reacts with the atmosphere, researching how molecules interact, etc.  The list can go on forever.  So, if something is made up of atoms or molecules and they react in anyway to anything, chemistry is important.

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Do different kinds of fruit conduct different amounts of electricity?  How can it be measured?

ANSWER from Imagiverse on 24 April 2006:
How well a fruit conducts electricity will depend on its composition and its effectiveness to transfer "ions".  Have you ever done experiments in school where you have used a voltmeter where you stick two wires into a lemon?  How about the use of a conductivity tester, by which a light bulb will glow with varying amounts of intensity?  A lemon will conduct electricity very well since it has a lot of stuff called ions and the ions can move around from one wire to the other pretty quickly.  There are many different ways to measure conductivity.  I suggest you ask your science teacher or the local science center about how you can do experiments like this.  Be careful when conducting experiments with electricity and always have an adult around.

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In many scientific measurements, one defines the atmosphere of the experiment/test bed to be air.  For example, air at STP (Standard Temperature and Pressure) and SATP (Standard Ambient Temperature and Pressure).

For these standards, what exactly comprises of air?  What is the elemental composition of air for this standard measurement?

ANSWER from Raúl Quesada on 4 August 2003:
Composition of air is the following:
Nitrogen 78.03%
Oxygen 20.99%
Carbon dioxide 0.035%
Argon 0.94% and other noble gases 0.0024%
Hydrogen 0.00005%

These values may change depending on weather conditions, road traffic (adding carbon monoxide, for instance), photosyntesis proccesses and industrial activity, etc.

To most of experiments, at least in Chemistry, where those mentioned standards are widely applied, it is enough to consider approximately 21% Oxygen and 78% Nitrogen.

Raúl Quesada
Chemistry Student

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11 July 2007

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