搜题请搜索小程序“爱下问搜题”
问题 填空题

常温下，如果取0.1 mol·L－1 HA溶液与0.1 mol·L－1 NaOH溶液等体积混合(忽略混合后溶液体积的变化)，测得混合溶液的pH＝8，试回答以下问题：

(1)混合溶液的pH＝8的原因(用离子方程式表示)：                       。

(2)混合溶液中由水电离出的c(OH－)       (填“＞”、“＜”或“＝”)0.1 mol·L－1 NaOH溶液中由水电离出的c(OH－)。

(3)求出混合溶液中下列算式的精确计算结果(填具体数字)：c(Na＋)－c(A－)＝       mol·L－1，c(OH－)－c(HA)＝       mol·L－1。

(4)已知NH4A溶液为中性，又知HA溶液加到Na2CO3溶液中有气体放出，试推断(NH4)2CO3溶液的pH       7(填“＞”、“＜”或“＝”)；将同温度下等浓度的四种盐溶液：

A．NH4HCO3     B．NH4A      C．(NH4)2SO4     D．NH4Cl

按pH由大到小的顺序排列是       (填序号)。

答案

(1)A－＋H2OHA＋OH－

(2)＞

(3)9.9×10－7　10－8

(4)＞　A＞B＞D＞C

(2)混合溶液由于A－水解，促进水的电离，而NaOH抑制水的电离。

(3)一开始c(Na＋)＝c(A－)，但Na＋不水解，A－水解，c(Na＋)与c(A－)之差即为水解的A－的量。pH＝8，c(H＋)＝10－8 mol·L－1，c(OH－)＝10－6 mol·L－1。

由H2O电离的c(OH－)H2O＝c(H＋)＝10－8 mol·L－1

A－＋H2OHA＋OH－

则c(Na＋)－c(A－)＝c(OH－)－c(OH－)H2O＝9.9×10－7 mol·L－1

c(OH－)－c(HA)＝10－6 mol·L－1－9.9×10－7 mol·L－1＝10－8 mol·L－1

(4)NH4A溶液为中性，说明NH4+与A－的水解程度相当，而HA加到Na2CO3中有气体放出，说明HA酸性强于H2CO3，CO32-水解程度大于A－，因而(NH4)2CO3溶液pH＞7，NH4HCO3溶液的pH也同样大于7。Cl－和SO42-不水解，所以(NH4)2SO4和NH4Cl溶液显酸性，但(NH4)2SO4中NH4+更多，水解程度更大，因而pH[(NH4)2SO4]＜pH(NH4Cl)＜7＝pH(NH4A)＜pH(NH4HCO3)。

多项选择题 案例分析题

患者男，65岁。主因渐进性意识障碍7h入院。既往有高血压和糖尿病史。体格检查：T36.7℃，P123次/min，R23次/min，BP125/90mmHg。昏迷状，颈软，瞳孔等大。

急诊应尽快做的紧急处理包括（）(提示　患者昏迷前长时间应用利尿药。尿酮体（-），尿糖（++++）。)

A.静脉输注0.9%氯化钠溶液

B.吸氧

C.胰岛素

D.抗凝治疗

E.抗生素

F.静脉输注碱性液体
查看答案
阅读理解

[1]Why is physical education important for students? There are many reasons. First of all, this subject helps them achieve the primary goal of physical education, which is physical fitness. As part of this, they can learn that it is highly important to include exercise and physical activities as part of their lifestyle.

[2]Physical education helps children achieve a healthy lifestyle. Inside the classroom, teachers educate kids about highly relevant issues such as the importance of hygiene (卫生) and health. This subject will help them realize the importance of having strong bodies. Likewise, it will also teach them how to have a healthy and an active lifestyle.

[3]Taking PE classes can help              of students. Being confident is very important to them as they grow and become responsible as well as competitive adults someday. This aspect (方面) of physical education is extremely important in the character development of students. Furthermore, it will teach them how to have a positive attitude.

[4]Physical education can teach students a set of all-important values. For example, it teaches students to fight like sportsmen and to cooperate with others to achieve one common goal as a team.

[5]Physical education also helps students develop their motor skills. On this kind of program, they are placed in situations where they can further develop and improve their reflexes (反应), concentration and body posture. By taking this class, they can realize their full potential as individuals and as part of a team.

[6]Moreover, physical education is also a means of enjoyment for students. By engaging in sports and physical activities, they can spend some pleasant time away from their other usual academic subjects. By doing so, they can achieve healthy minds and bodies.

小题1:What’s the text mainly about? (no more than 6 words)

小题2:What does the underlined word “it” (Line 3 paragraph 2) probably refer to? (no more than 3 words)

小题3:Fill in the blank in Paragraph 3 with proper words. (no more than 4 words)

小题4:Based on the text, list two values that students can learn in PE classes. (no more than 6 words)

小题5:How can a student keep healthy physically and mentally? (no more than 9 words)
查看答案