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Although weight is related to mass, it is not the same thing. Weight refers to the force that gravity exerts on an object. This force is directly proportional to the mass of the object. The weight of an object changes as the force of gravity changes, but its mass does not. An astronaut’s mass does not change just because she goes to the moon. But her weight on the moon is only one-sixth her earth-bound weight because the moon’s gravity is only one-sixth that of the earth’s. She may feel “weightless” during her trip when she experiences negligible external forces (gravitational or any other), although she is, of course, never “massless.”

The law of conservation of matter    summarizes many scientific observations about matter: It states that there is no detectable change in the total quantity of matter present when matter converts from one type to another (a chemical change) or changes among solid, liquid, or gaseous states (a physical change) . Brewing beer and the operation of batteries provide examples of the conservation of matter ( [link] ). During the brewing of beer, the ingredients (water, yeast, grains, malt, hops, and sugar) are converted into beer (water, alcohol, carbonation, and flavoring substances) with no actual loss of substance. This is most clearly seen during the bottling process, when glucose turns into ethanol and carbon dioxide, and the total mass of the substances does not change. This can also be seen in a lead-acid car battery: The original substances (lead, lead oxide, and sulfuric acid), which are capable of producing electricity, are changed into other substances (lead sulfate and water) that do not produce electricity, with no change in the actual amount of matter.

Diagram A shows a beer bottle containing pre-beer and sugar. An arrow points from this bottle to a second bottle. This second bottle contains the same volume of liquid, however, the sugar has been converted into ethanol and carbonation as beer was made. Diagram B shows a car battery that contains sheets of P B and P B O subscript 2 along with H subscript 2 S O subscript 4. After the battery is used, it contains an equal mass of P B S O subscript 4 and H subscript 2 O.
(a) The mass of beer precursor materials is the same as the mass of beer produced: Sugar has become alcohol and carbonation. (b) The mass of the lead, lead oxide plates, and sulfuric acid that goes into the production of electricity is exactly equal to the mass of lead sulfate and water that is formed.

Although this conservation law holds true for all conversions of matter, convincing examples are few and far between because, outside of the controlled conditions in a laboratory, we seldom collect all of the material that is produced during a particular conversion. For example, when you eat, digest, and assimilate food, all of the matter in the original food is preserved. But because some of the matter is incorporated into your body, and much is excreted as various types of waste, it is challenging to verify by measurement.

Atoms and molecules

An atom    is the smallest particle of an element that has the properties of that element and can enter into a chemical combination. Consider the element gold, for example. Imagine cutting a gold nugget in half, then cutting one of the halves in half, and repeating this process until a piece of gold remained that was so small that it could not be cut in half (regardless of how tiny your knife may be). This minimally sized piece of gold is an atom (from the Greek atomos , meaning “indivisible”) ( [link] ). This atom would no longer be gold if it were divided any further.

Questions & Answers

very brief information on collision theory
what does the term resistance means
Clifford Reply
matter is anything that has mass and occupied space.
sunday Reply
okk tanx
what is matter
Abdulhameed Reply
list mixtures and their components
Clement Reply
describe how Ethene reacts with bromine
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good evening all am now here
Onah Reply
what happening here
the principles and applications of extraction chromatographic methods in the isolation and purification of organic compounds
Precious Reply
what is the dislocation of CH³COOH
Abdul Reply
another name for alkane ?
adeyeye Reply
what is the chemical formula for benzene
Emmanuel Reply
Benzene C6H6
what does each group on the periodic table stand for
Chidera Reply
what's lanthanide series
kimah Reply
lanthanide series are element in the 4f block from 57 to 70
lanthanide series consist of F block element in the first series in the end of the periodic table..they are placed separately in the periodic table.because they possess different properties than rest of the elements!
whats is Dalton's law
Wanger Reply
What is the real definition of chemistry
tony Reply
chemistry can be defined as one of the branchs of science that deals with the state and changes which matter undergoes
Who can write this organic chemistry 3-ethyl-1,1,4-trimethyl pentane
what is the formula of Benzene
formula of benzene C6H6
benzene is a cyclohexane c6h6
cyclohexene C6H6
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how do you know if a periodic table is complete or not
Emmanuel Reply
just find out the alkali metals,alkaline earth metals,the halogens, noble gases and transition metals.

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Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
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