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| [[Category:Done 2015-07-24]] | | #REDIRECT [[Concentration in parts per]] |
| <onlyinclude>'''Ppm''' or '''parts per million''' is a dimensionless quantity used to describe the ratio of an amount of substance within another substance, specifically denoting 1 part per 1 000 000 parts.</onlyinclude> It is used similarly to percents (%) which are in fact just a measure of a part per hundred (1% = pph), however it compares quantities on a much smaller scale. For instance, 32 seconds would be roughly equivalent to one ppm of a year,<ref><m>31557600 \frac{seconds}{year} \div 1000000 = 31.557 seconds \approx 32 seconds </m></ref> and a [[millimeter]] is one ppm of a [[kilometer]].
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| Ppm is commonly used to describe quantities of trace substances in order to communicate abundance; such as [[carbon dioxide]] in the [[atmosphere]] or the abundance of [[uranium]] within the Earth's [[Cross section of the Earth|crust]].
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| ==References==
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| {{reflist}}
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| [[Category:Uploaded]] | |
