作者catspace (柏拉图的永恒...)
看板GMAT
标题Re: [计量] PP1-PS
时间Wed Nov 5 23:34:31 2008
※ 引述《aaaaaakoyasu (六点半天色还没亮)》之铭言:
: 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
: percent 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
: 题目看没有很懂...拜托了<(_ _)>
反应速率R与A^2成正比
与 B 成反比
所以R = A^2 / B
令新的反应速率 R` = A`^2 / B` 由题目得知 B` = 2B
若速率不变则 R` = R 由关系式得知 A`^2 = 2*A^2
则A`=(根号2)*A 变动率为 (根号2)-1 = 1.414 -1 = 40% #
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1F:推 aaaaaakoyasu:原来如此...非常感谢你<(_ _)> 11/06 09:51