问题 选择题

新型净水剂—高铁酸钾(K2FeO4)为暗紫色固体,可溶于水。工业上制备K2FeO4的常用方法之一是次氯酸盐氧化法:①2FeCl3+10NaOH+3NaClO=2Na2FeO4+9NaCl+5H2O、②Na2FeO4+2KOH=K2FeO4+2NaOH。下列说法不正确的是

A.反应①为氧化还原反应,反应②为复分解反应

B.反应①中氧化产物与还原产物物质的量之比为2:9

C.反应②的产物K2FeO4中Fe为+6价,具有强氧化性,能杀菌消毒

D.若有2mol FeCl3发生反应,转移电子的物质的量为6 mol

答案

答案:B

题目分析:A、根据方程式2FeCl3+10NaOH+3NaClO=2Na2FeO4+9NaCl+5H2O可知,铁元素的化合价从+3价升高到+6价,失去3个电子,被氧化,因此氯化铁是还原剂。氯元素的化合价从+1价降低到-1价,得到2个电子,被还原,所以次氯酸钠是氧化剂,即反应①是氧化还原反应。而反应②是离子间相互交换成分,生成另外一种盐和另外一种碱,因此是复分解反应,A正确;B、反应①中氧化产物是高铁酸钠,还原产物是氯化钠。由于还原剂与氧化剂的物质的量之比是2:3,因此反应中氧化产物与还原产物物质的量之比为2:3,B不正确;C、反应②的产物K2FeO4中Fe为+6价,价态高,易得到电子,具有强氧化性,能杀菌消毒,C正确;D、铁元素的化合价从+3价升高到+6价,失去3个电子,因此若有2mol FeCl3发生反应,转移电子的物质的量为6 mol,D正确,答案选B。

多项选择题
阅读理解

Forget chip fat, sugar cane or rapeseed oil — the latest source of biofuel could be watermelons. Scientists have discovered that the fruit is a great source of sugar that can be readily distilled (蒸馏) into alcohol to power cars and farm machinery.

And sellers reject 360,000 tons of “substandard” fruit every year in America alone which could be used as an economical way to make fuel. The waste from US growers could produce nearly two million gallons (nine million litres) of biofuel per year.

In the study, researchers at the United States Department of Agriculture set out to determine the biofuel potential of juice from rejected watermelons —those not sold due to cosmetic imperfections, and currently ploughed back into the field. About a fifth of each yearly watermelon crop is left in the field because of surface blemishes (瑕疵) or because they are misshapen.

Dr. Wayne Fish, who led the team, found that 50 percent of the fruit was fermentable (可发酵的) into alcohol which could provide valuable fuel.

“We’ve shown that the juice of these watermelons is a source of readily fermentable sugars, representing an unexploited raw material for alcohol biofuel production,” he said.

The study, published in the journal Biotechnology for Biofuels, discovered that watermelons could produce around 20 gallons of fuel per acre from fruit that otherwise would go to waste.

Production of biofuels has been targeted by Western governments as a way to support renewable energy targets.

The European Union has a target for 2010 that 5.75 percent of transport fuels should come from biological sources, but the target is unlikely to be met.

The British government’s Renewable Transport Fuel Obligation requires five percent of the fuel sold at the pump by 2010 to be biofuel.

小题1:The passage mainly tells us ______.

A.watermelon juice will be the largest source of renewable energy

B.the advantages of fuel made from watermelons

C.Western countries aim at producing biofuels

D.watermelons could be used to make fuel小题2: It can be learned from the text that ______.

A.about two gallons of fuel could be made from rejected fruit per acre

B.sellers in the world throw away 360,000 tons of watermelons every year

C.half of the watermelons were fermentable into alcohol to provide energy

D.five percent of fuel is required to be biofuel from watermelons by 2010 in Britain小题3:The underlined word “cosmetic” in Paragraph 3 probably means ______.

A.fresh

B.sweet

C.surface

D.inside小题4:We can infer from the passage that ______.

A.it will cost a lot to make biofuel from watermelons

B.Western countries are engaged in biofuel study but still have a long way to go

C.watermelon juice has been used as a source of sugars to produce alcohol biofuel

D.the European Union is likely to meet its target of transport fuels from biological sources