问题 问答题 简答题

称取工业原料氟化钙0.5000g,于250ml烧杯中,加水使试样湿润,用盐酸及硼酸溶解以后移动入250ml容量瓶中,用水稀释至刻度.移取25ml于锥形瓶中,加入三乙醇胺掩蔽杂质铁,铝,在PH=12时,用0.02000mol/LEDTA溶液滴定,问约消耗EDTA溶液多少毫升?提示:工业原料CaF2一般含量为98%左右,CaF2的摩尔质量为78.08g/mol

答案

参考答案:

已知工业原料CaF2含量为98%

W=0.5000g,cEDTA=0.02000mol/LCaF2的摩尔质量为78.08g/mol;

CaF2与EDTA的物质的量比(摩尔比)为1:1反应中CaF2的物质的量等于

EDTA标准溶液的物质的量则:

cEDTAXvEDTA=W×98%×25/250/78.08g/mol

vEDTA=(W×98%×25/250×1000ml)/(78.08×cEDTA.

=(0.5×0.98×25/250×1000ml)/(78.08×0.02000)=31.38ml

单项选择题
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Is getting a black belt(腰带) on your life’s to-do list? Then this elderly woman in San Francisco just might be your hero.

Just two years before her 100th birthday, Sensei Keiko Fukuda has become the first woman to achieve a tenth-degree black belt --- the highest rank in Judo (柔道). Fukuda is now one of only four living people who have earned the tenth-degree black belt. Throughout history, only 16 people have ever achieved this honor.

Fukuda began practicing Judo in 1935 and is the only surviving student of its founder, Kano Jiguro.

At her teacher’s requirement, she learned English to help spread Judo internationally.

During a time when getting married, building a family and becoming a housewife were the norms(行为标准),Fukuda broke from tradition, continuing Judo instead of getting married.

“All I did was Judo ... This was my marriage,” Fukuda replied tearfully to the San Francisco Chronicle. “This is when my destiny (命运) was set. I just imagined how long the road would be.”

She described the Jiguro’s school as “old-fashioned and sexist(性别歧视的) about belts and ranks”. In fact, an edict(法令) that prevented women from achieving any higher than a fifth-degree black belt kept Fukuda at that level for 30 years. She finally got the sixth degree in 1972 when a women’s division(分部)was created.

Fukuda thinks Judo and her life to be “gentle, kind and beautiful, yet firm and strong, both mentally and physically”. Fukuda says this kind of beauty is not external(外在的). She explained. “I believe this inner beauty is true beauty… All my life this has been my dream.”

Her dream was turned into reality, and the 98-year-old Sensei Keiko Fukuda continues to teach Judo three times a week at a women’s Judo training center.

小题1:Which of the following is NOT TRUE according to the article?

A.She is the first woman to achieve the highest rank in Judo.

B.It took her 30 years to get a tenth-degree black belt.

C.Her teacher wanted her to help spread Judo to other parts of the world.

D.Only one woman and fifteen men have ever earned the tenth-degree black belt in the history.小题2:Why did Fukuda pursue(追求) Judo all her life?

A.To look for inner beauty.

B.To help Japan become stronger.

C.To spread Judo around the world.

D.To fight against tradition.小题3:Which of the following best describes Fukuda according to the article?

A.Traditional

B.Popular

C.Determined (坚定的)

D.Curious