问题 填空题

有一种氯化钠与氯化钾的混合物,它所含钾与钠的物质的量之比为3∶1,求:

(1)混合物中氯化钾的质 量分数。

(2)含1 mol Cl的混合物的质量。

答案

(1)79.3%(2)70.5 g

题目分析:(1)则设混合物中有1mol的氯化钠,则氯化钾有3mol,混合物的总质量=1*58.5+3*74.5=282g,所以氯化钾的质量分数=(74.5*3/282)*100%=79.3%

(2)总的氯离子为1mol,所以氯化钾为0.75mol,氯化钠为0.25mol,所以混合物的质量="0.75*74.5+0.25*58.5=70.5" g

点评:本题抓住在氯化钾中,氯离子的物质的量等于钾离子的物质的量等于氯化钾的物质的量,而且计算过程中需要对物质的量与质量间的换算非常熟练。

完形填空
I walked into the grocery store not particularly interested in buying something. The sorrow of   1  my husband of 37 years was still too painful. And this grocery store held so many sweet  2 . Bob often came with me and almost every time he'd  3  to go off and look for something special. I'd always see him walking down the walkway   4  the three yellow roses in his hands. Bob knew I loved yellow roses. With a heart   5  with pain, I came to the meat shelf, I searched for the  6  small steak and remembered how Bob had loved his steak.
Suddenly a woman came beside me. She was in a soft green dress. I   7  as she picked up a large pack of T-bones,   8  them in her basket, hesitated, and then put them back. She saw me watching her and she smiled. "My husband loves T-bones, but   9 , at these prices, I don't know."
"My husband passed away eight days ago," I told her. "Buy him the steaks. And value every   10  you have together."
She smiled and I saw the feeling in her   11  as she placed the package in her basket and   12  away. I turned and pushed my cart forward too. Several minutes later I saw first the green suit and then  13  the pretty lady coming to me. In her arms she carried something. On her face was the   14  smile I had ever seen.
As she came closer, I saw what she held and   15  welled down. "These are for you, " she said and placed three beautiful yellow roses in my arms. She placed a gentle kiss on my cheek, then smiled again. I wanted to tell her what the roses   16 , but still unable to speak. I watched as she walked away as tears clouded my   17 . I looked down at the beautiful roses and found it almost  18 . How did she know?
Suddenly the   19  seemed so clear. I wasn't alone. "Oh, Bob, you haven't   20  me, have you?" I whispered, with tears in my eyes. He was still with me, and she was his angel.
小题1:
A.leavingB.losingC.passingD.failing
小题2:
A.flowersB.rosesC.thoughtsD.memories
小题3:
A.pretendB.happenC.refuseD.decide
小题4:
A.byB.betweenC.withD.during
小题5:
A.fullB.pleasedC.filledD.crowded
小题6:
A.perfect B.beautifulC.prettyD.very
小题7:
A.sawB.watchedC.foundD.glared
小题8:
A.fellB.carriedC.tookD.dropped
小题9:
A.honestlyB.generallyC.usuallyD.exactly
小题10:
A.dinnerB.momentC.timeD.year
小题11:
A.handsB.voiceC.eyesD.basket
小题12:
A.wheeledB.ranC.slippedD.left
小题13:
A.realizedB.thoughtC.recognizedD.received
小题14:
A.saddestB.funniestC.strangestD.brightest
小题15:
A.wordsB.feelingsC.tearsD.sweats
小题16:
A.stoodB.describedC.designedD.meant
小题17:
A.cartB.sightC.rosesD.package
小题18:
A.unknownB.uncommonC.unlikeD.unreal
小题19:
A.questionB.caseC.answerD.puzzle
小题20:
A.forgottenB.disappointedC.hatedD.missed
单项选择题