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%, 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
correct answer: d
我没弄明白题干,请大家指点一下,万分感谢!
化学反映的速率跟A物质的浓度的平方成正比,跟B物质的浓度成反比,现在B的浓度增长了100%,问A的浓度增长多上才能保证反映速率不变。
设原来速率为r,原来B的浓度为b,原来A的浓度为a,所求A的浓度为A,那么列出方程:
r=k(a^2)/(tb)=k(A^2)/(t2b),其中k和t为自设定的比率,常数。
解方程得:A=(根号2)*a,所以选D
欢迎光临 国际顶尖MBA申请交流平台--TOPWAY MBA (http://forum.topway.org/) | Powered by Discuz! 7.2 |