问题:

做PREP时遇到的数学难题,请牛人指教1、TherateofacertainchemicalreactionisdirectlyproportaionaltothesquareoftheconcentrationofchemicalApresentandinverselyproportionaltotheconcentrationofchemicalBpresent.Ifthe

更新时间:2024-04-20 07:58:06 数学

问题描述:

做PREP时遇到的数学难题,请牛人指教

1、TherateofacertainchemicalreactionisdirectlyproportaionaltothesquareoftheconcentrationofchemicalApresentandinverselyproportionaltotheconcentrationofchemicalBpresent.IftheconcentrationofchemicalBisincreasedby100%,whichofthefollowingisclosesttothepercentchangeintheconcentrationofchemicalArequiredtokeepthereactionrateunchanged?

(a)100%decrease(b)50%decrease(c)40%decrease(d)40%increase(e)50%increase

康向平回答:

  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%

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