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Proportions Question

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Junior | Next Rank: 30 Posts
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by gvosough » Mon Feb 14, 2011 2:35 pm
The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the precent change in the concentration of chemical A required to keep the reaction rate unchanged?
A) 100% decrease
B) 50% decrease
C) 40% decrease
D) 40% increase
E) 50% increase

Thanks,

OA: D
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by Night reader » Mon Feb 14, 2011 2:45 pm
R=(A^2)/(B); R=(A`^2)/(2B) --> (A*x%)^2=2*(A^2), (A^2)*(x^2)%=2*(A^2), (x^2)%=2 --> x=Sqrt(2) OR 1.41
1.41*100=141% --> 41% increase in A.
IOM D
gvosough wrote:The rate of a certain chemical reaction is directly proportional to the square of the concentration of chemical A present and inversely proportional to the concentration of chemical B present. If the concentration of chemical B is increased by 100 percent, which of the following is closest to the precent change in the concentration of chemical A required to keep the reaction rate unchanged?
A) 100% decrease
B) 50% decrease
C) 40% decrease
D) 40% increase
E) 50% increase

Thanks,

OA: D
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