(12分)以硫铁矿为原料生产硫酸所得的酸性废水中砷元素含量极高,为控制砷的排放,

题型:填空题

问题:

(12分)以硫铁矿为原料生产硫酸所得的酸性废水中砷元素含量极高,为控制砷的排放,采用化学沉降法处理含砷废水,相关数据如下表。

难溶物Ksp
Ca3(AsO4)26.8×10-19
AlAsO41.6×10-16
FeAsO45.7×10-21
表1.几种砷酸盐的Ksp       

污染物H2SO4As
浓度28.42 g/L1.6 g·L-1
排放标准pH 6~90.5 mg·L-1
表2.工厂污染物排放浓度及允许排放标准

回答以下问题:

⑴该硫酸工厂排放的废水中硫酸的物质的量浓度c(H2SO4)=______________mol·L-1

⑵写出难溶物Ca3(AsO4)2的Ksp表达式:Ksp[Ca3(AsO4)2]=______________,若混合溶液

中Al3、Fe3的浓度均为1.0×10-4mol·L-1,c(AsO43)的最大是_______________mol·L-1

⑶工厂排放出的酸性废水中的三价砷(H3AsO3弱酸)不易沉降,可投入MnO2先将其氧化成五价砷(H3AsO4弱酸),写出该反应的离子方程式________________________________。

⑷在处理含砷废水时采用分段式,先向废水中投入生石灰调节pH到2,再投入生石灰将pH

调节到8左右使五价砷以Ca3(AsO4)2形式沉降。

①将pH调节到2时废水中有大量沉淀产生,沉淀主要成分的化学式为______________;

②Ca3(AsO4)2在pH调节到8左右才开始沉淀的原因为_____________________________。

考点:光导纤维新型材料(新型陶瓷、单晶硅等)塑料、纤维、橡胶复合材料
题型:填空题

下列画线字读音完全正确的一项是[ ]

A.蹂(lìn)          (tuò)变           (níng)视        枯(hé)

B.卖(lòng)        (diàn)污         头晕目(xuàn)

C.玲珑(tī)透     (chéng)清       (chú)形

D.(pá)窃          (cùi)然长逝    忍俊不(jīn)     (xī)息

题型:填空题

有一种物质的化学式为Na2SiO3,其中Si的化合价为[ ]

A.+1

B.+2

C.+3

D.+4

题型:填空题

什么健康,对不同生活内容的理解,以及关心和尊重所有生命体的能力。()

A.智力健康

B.情绪健康

C.精神健康

D.社交健康

题型:填空题

Part 4


Questions 26-45


·Read the following passage and decide which answer best fits each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.
Participation (26) high school sports is not a constitutional right. (27) , it is a privilege, paid for by taxpayers, open to students who promise to (28) certain conduct requirements on and off the field. One of these promises is to (29) from using drugs. Drug use is a serious problem among high school students. Studies show that as many as 500, 000 high school students use muscle-pumping, life-destroying substances such as steroids. Many more use illegal drugs, (30) cause discipline problems and (31) the stage for lifelong (32) .
Drug testing works to (33) and identify use. That is why drug testing is required to compete in the Olympics, the National Collegiate Athletic Association and the National Football League. (34) drug testing was instituted by these organizations, use of performance- (35) drugs has been greatly reduced. We should want (36) in schools.
Indeed, many athletes (37) testing programs, and no wonder. Without testing, athletes have to choose between drug use and a competitive disadvantage (38) the field.
Those who challenge the need for drug testing may be forgetting (39) it is like be an adolescent. Peer pressure is enormous, and one of the few effective counter-weights is the fear of being caught. More importantly, once drug use is (40) , a school can (41) to the student before he or she gets addicted or arrested.
For 25 years, public schools (42) by federal judges and civil libertarians, with results everyone can see. It is time (43) decisions on how to run public schools locally (44) officials. There is nothing unconstitutional about asking those who gain the advantages of school-sponsored athletics to contribute to the safety of other players, the integrity of the game and their own well-being. The Supreme Court should leave these programs (45) .

A.But

B.Rather

C.Therefore

D.Thus

题型:填空题

补气养阴,清火生津,首选的药物是()

A.山药

B.西洋参

C.沙参

D.太子参

E.玄参

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