问题 填空题

(12分)某化学兴趣小组利用下图所示原电池装置进行实验,请回答下列问题:

(1)实验中,同学们发现两装置电流计的指针偏转方向不同,因此有人提出以下观点,其中正确的是____________。(双选题,漏选得1分,多选错选得0分)

A.金属活动性铝比镁强

B.金属活动性镁比铝强,两装置中镁均为负极

C.仅根据金属活动性顺序不能准确判断原电池的正负极

D.原电池中的正负极受电解质溶液的酸碱性、强氧化性等因素的影响(2)写出甲图中的电极反应式:

①正极:__________________________________________;

②负极:__________________________________________。

(3)乙图中铝片与NaOH溶液反应的总化学方程式为______________________。某同学测得乙图中实验前铝片的质量是10g,实验后的质量是4.6g,则在实验过程中产生氢气的体积为       L(标况),转移电子的物质的量为     mol。

答案

(1)CD(双选题,漏选得1分,多选错选得0分)

(2)①2H++2e==H2↑;   ②Mg - 2e==Mg2

(3)2Al + 2NaOH + 2H2O = 2NaAlO2 + 3H2↑      6.72L ,0.6mol

(1)在一般情况下,原电池中较活泼的金属作负极,较不活泼的金属作正极。但是还需要考虑所用的电解质溶液。由于镁和氢氧化钠不反应,铝和氢氧化钠反应,所以此时作负极的是铝,而不是镁,镁作正极。所以正确的答案是CD。

(2)甲装置中镁是负极,失去电子。铝是正极,溶液中的氢离子得到电子,生成氢气。

(3)铝和氢氧化钠反应生成氢气、偏铝酸钠和水,反应式为2Al + 2NaOH + 2H2O = 2NaAlO2 + 3H2↑。根据题意可知,消耗的铝是10g-4.6g=5.4g,物质的量是。所以生成氢气是0.3mol,转移电子是0.2mol×3=0.6mol。

单项选择题 案例分析题
单项选择题

Until the late 1940s, when television began finding its way into American homes, companies relied mainly on print and radio to promote their products and services. The advent of television (1) a revolution in product and service. Between 1949 and 1951, advertising on television grew 960 percent. Today the Internet is once again (2) promotion. By going online, companies can communicate instantly and directly with prospective customers. (3) on the World Wide Web includes advertising, sponsorships, and sales promotions (4) sweepstakes, contests, coupons, and rebates. In 1996 World Wide Web advertising revenues (5) $ 300 million.

Effective online marketers don’t (6) transfer hard-copy ads to cyberspace. (7) sites blend promotional and non-promotional information indirectly delivering the advertising messages. To (8) visits to their sites and to create and (9) customer loyalty, companies change information frequently and provide many opportunities for (10) .

A prototype for excellent (11) promotion is the Ragu Web site. Here visitors can find thirty-six pasta recipes, take Italian lessons, and view an Italian film festival, (12) they will find no traditional ads. (13) subtle is the mix of product and promotion that visitors hardly know an advertising message has been (14) . Sega of America, maker of computer games and hardware, uses its Web site for a (15) of different promotions, such as (16) new game characters to the public and supplying Web surfers the opportunity to (17) games. Sega’s home page averages 250,000 visits a day. To heighten interest in the site, Sega bought an advertising banner on Netscape (18) increasing site visits by 15 percent. Online (19) in Quaker Oats’ Gatorade promotion received a free T-shirt in exchange for answering a few questions. Quaker Oats reports that the online promotion created product (20) and helped the company know its customers better.

2()

A.transferring

B.transforming

C.transmitting

D.transplanting