问题 问答题

精密称取安定(M=284.8)样品14.40mg于100ml容量瓶中,再用0.5%硫酸甲醇溶液溶解,并稀释至刻度,摇匀。精密吸取10.00ml上述溶液,稀释至100.0ml。取该溶液在284nm处,用1cm吸收池测得吸光度值A为0.642,已知摩尔吸收系数为12896,试求安定的百分吸收系数及样品中安定的百分含量。

答案

参考答案:

解析:根据ε与E1%换算式
ε=M×E1%/10
E1%=10ε/M
=10×12896/284.6
=453
%=[(A/EL)×稀释倍数]/Ws×100%
=[(0.642/453)×1000/x100]/0.0144×100%
=98.42%

阅读理解

根据短文内容,完成下列短文。每空一词。

     A little old man and his wife walked slowly into McDonald's on a cold winter evening. The little old

man walked to the cashier (收银处) to order.

     There was one hamburger, some French fries and one drink. He carefully divided the hamburger in

half and the French fries in two piles. Then he neatly put the half of the food in front of his wife. Both he

and his wife took a sip (一小口) of the drink. "How poor the old couple are!" the people around them

might think. As the old man started to eat his hamburger and his French fries, his wife sat there watching

him. They took turns to drink. A young man came over and offered to buy another meal for them. But

they refused politely and said they got used to sharing everything; Then a young lady asked the wife,

"Excuse me, Madam, why aren't you eating? You said that you shared everything. Then, could you tell

me what you are waiting for?" She answered in a smile, "The teeth. "

     One evening, a little old man and his wife walked slowly into McDonald's. They     1    one hamburger,

some French fries and one drink . The little old man     2     the food into two portions. They took a sip

of the drink. As the old man started to eat food, his wife sat there     3     him. They took turns to drink.

A young man offered to buy     4     meal for them. But they refused and said they got used to     5    

everything. A young lady asked the wife what she was waiting for. She said she was waiting for "The

teeth. "

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