document.write( "Question 1187683: A substance in a chemical reaction is used up at a rate that is proportional to the
\n" ); document.write( "amount of the substance present at any time. If ½ of the substance is used up in 2
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Algebra.Com's Answer #818699 by ikleyn(52866) $\"\"$ $\"About$

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\n" ); document.write( "A substance in a chemical reaction is used up at a rate that is proportional to the
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document.write( "Since the substance in a chemical reaction is used up at a rate that is proportional \r\n" );
document.write( "to the amount of the substance present at any time, we have classical exponential decay of the substance.\r\n" );
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document.write( "We also are given that the half-life time of this substance decay is 2 hours.\r\n" );
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document.write( "Since  2 hours and 30 minutes is   = 1.25 half-periods,  the remaining mass \r\n" );
document.write( "at the end of 2 hours and 30 minutes will be\r\n" );
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document.write( "     = 0.420448 = 0.420  (rounded)  \r\n" );
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document.write( "of the original amount of the substance in the reaction.\r\n" );
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\n" ); document.write( "\n" ); document.write( "Solved, answered and explained in all details.\r
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