问题 填空题

分子筛具有吸附能力强,热稳定性高等优良性能,使得分子筛获得广泛应用,某种型号分子筛的工业生产流程可表示如下:

在滴加氨水调节pH=9的过程中,若pH控制不当,会有Al(OH)3生成,假设生产过程中铝元素、硅元素均没有损失,钠原子利用率为10%。

(1)分子筛的直径为4A(1A=10-10m)称为4A型分子筛,当Na+被Ca2+取代时就制得5A型分子筛,当Na+被K+取代时就制得6A型分子筛。要高效分离正丁烷(分子直径为4.65A)和异丁烷(分子直径为5.6A)应该选用_______型分子筛。

(2)Al2(SO4)3溶液与Na2SiO3溶液反应生成胶体的离子方程式为________________________

(3)该生产流程中所得滤液里含有的离子除H+、OH外,主要还有         等离子。检验其中金属阳离子的操作方法是            

(4)加NH3•H2O调节pH后,加热到90℃并趁热过滤的原因可能是                  

(5)该生产流程中所得分子筛的化学式为                 。(用氧化物形式表示)

答案

(1)5A(2)2Al3++3SiO32-+6H2O=2Al(OH)3+3H2SiO3

(3)Na+,NH4+,SO42-;将铂丝(或铁丝)在酒精灯上加热至无色,蘸取待测溶液放在酒精灯外焰上灼烧,若火焰呈黄色,则待测液中含有Na+;

(4)加热能促使胶体凝聚,趁热过滤可防止其它杂质晶体析出。

(5)Na2O·Al2O3·10SiO2·6H2O

题目分析:(1)由于正丁烷的分子直径为4.65A,异丁烷的分子直径为5.6A,所以应该选择5A型分子筛才可以将二者分离开。(2)Al2(SO4)3是强酸弱碱盐, Na2SiO3是强碱弱酸盐,二者在溶液反应生成胶体的离子方程式为2Al3++3SiO32-+6H2O=2Al(OH)3+3H2SiO3。(3)根据质量守恒定律,可知在该生产流程中所得滤液里含有的离子除H+、OH外,主要还有Na+、NH4+、SO42-。可以用焰色反应来检验其中金属阳离子Na+。具体操作方法是将铂丝(或铁丝)在酒精灯上加热至无色,蘸取待测溶液放在酒精灯外焰上灼烧,若观察到火焰呈黄色,则待测液中含有Na+。(4)加NH3•H2O调节pH后,加热到90℃并趁热过滤是因为加热能促使胶体凝聚,趁热过滤可防止其它杂质晶体析出而导致胶体不纯。(5)由于在生产过程中铝元素、硅元素均没有损失,钠原子利用率为10%。n(Al)=(34.2g÷342g/mol)×2=0.2mol;n(Si)=122g÷122g/mol=1mol;n(Na)=2n(Si)=2mol。所以在胶体中的Al:0.2mol;Si:1mol;Na: 2mol×10%=0.2mol;由于在化合物中的正负化合价的代数和为0,所以2n(O)=0.2×3+1×4+0.2×1.解得n(O)=2.4.所以n(Na): n(Al): n(Si): n(O)=0.2:0.2:1:2.4=1:1:5:12.由于分子筛的化学式为NaxAlySiZOn·mH2O。质量为87.2g.{87.2g÷(382+18m)g/mol}×1=0.2;解得m=3.因此该分子筛的化学式为NaAlSi5O12·3H2O.分子筛可以用不同的形式表示。在变化的过程中个元素的物质的量的比不能发生变化。所以用氧化物的形式表示为Na2O·Al2O3·10SiO2·6H2O。

单项选择题

Social-networking sites offer users easy ways to present idealized images of themselves, even if those ideals don’t always square with their real-world personalities. Psychology researcher Soraya Mehdizadeh has discovered a way to poke through the offline-online curtain: she has used Faeebook to predict a person’s level of narcissism and self-esteem.

Mehdizadeh, who conducted the study as an undergraduate at Toronto’s York University, gained access to the Faeebook accounts of 100 college students and measured activities like photo sharing, wall postings and status updates; she also studied how frequently users logged on and how often they remained online during each session. Her findings were published recently in Cyberpsyehology, Behavior and Social Networking.

After measuring each subject using the Narcissism Personality Inventory and Rosenberg Self-Esteem Scale, Mehdizadeh, who graduated from York this past spring, discovered narcissists and people with lower self-esteem were more likely to spend more than an hour a day on Facebook and were more prone to post self-promo-tional photos ( striking a pose or using Photoshop, for example). Narcissists were also more likely to showcase themselves through status updates (using phrases like "I’m so glamorous I bleed glitter") and wall activity (posting self-serving links like " My Celebrity Look-alikes" ).

Self-esteem and narcissism are often interrelated but don’t always go hand in hand. Some psychologists believe that narcissists--those who have a pervasive pattern of grandiosity, a need for admiration, as well as a lack of sympathy--unconsciously inflate their sense of self-importance as a defense against feeling inadequate. Not enough empirical research has been produced to confirm that link, although Mehdizadeh’s study seems to support it. Because narcissists have less capacity to sustain intimate or long-term relationships, Mehdizadeh thinks that they would be more drawn to the online world of virtual friends and emotionally detached communication.

Although it seems that Facebook can be used by narcissists to fuel their inflated egos, Mehdizadeh stops short of proclaiming that excessive time spent on Faeebook can turn regular users into narcissists. She also notes that social-networking sites might ultimately be found to have positive effects when used by people with low self-esteem or depression. "If individuals with lower self-esteem are more prone to using Facebook," she says, "the question becomes, ’ Can Facebook help raise self- esteem by allowing patients to talk to each other and help each other in a socially interactive environment’ I don’t think it’s necessarily a bad thing that people with low self-esteem use Facebook.

which of the following is used for predicting a person’s level of narcissism and self-esteem()

A. Activities the subjects take apart in

B. Frequency of the experimental object

C. Frequency of the experimental object’s renewing photos

D. The contents of the log of the experimental object

判断题