做PREP时遇到的数学难题,请牛人指教
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做PREP时遇到的数学难题,请牛人指教
1、The rate of a certain chemical reaction is directly proportaional 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
1、The rate of a certain chemical reaction is directly proportaional 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
![做PREP时遇到的数学难题,请牛人指教](/uploads/image/z/17828625-57-5.jpg?t=%E5%81%9APREP%E6%97%B6%E9%81%87%E5%88%B0%E7%9A%84%E6%95%B0%E5%AD%A6%E9%9A%BE%E9%A2%98%2C%E8%AF%B7%E7%89%9B%E4%BA%BA%E6%8C%87%E6%95%99)
第一题
关键词:
rate速度,proportional成比例的,concentration浓度,inversely相反地
反应速率=k*(A^2)*(1/B)
B上升100%后,B'=(1+100%)B=2B
要反应速度不变,需要k*(A^2)*(1/B)=k*(A'^2)*(1/B')
k约掉,B'代入,(A^2)*(1/B)=(A'^2)*(1/2B)
B约掉,A’^2=2*(A^2)
两边开根号,A'=根号2*A
根号2=1.414,故上涨40%
关键词:
rate速度,proportional成比例的,concentration浓度,inversely相反地
反应速率=k*(A^2)*(1/B)
B上升100%后,B'=(1+100%)B=2B
要反应速度不变,需要k*(A^2)*(1/B)=k*(A'^2)*(1/B')
k约掉,B'代入,(A^2)*(1/B)=(A'^2)*(1/2B)
B约掉,A’^2=2*(A^2)
两边开根号,A'=根号2*A
根号2=1.414,故上涨40%