皮皮学，免费搜题
登录
搜题
【简答题】
铬铁矿主要成分为FeO·Cr 2 O 3 ，还含有杂质Al 2 O 3 。一般铬铁矿中Cr 2 O 3 质量分数约为40％。由铬铁矿制备重铬酸钾的方法如下： 已知： ①4FeO·Cr 2 O 3 ＋8Na 2 CO 3 ＋7O 2 8Na 2 CrO 4 ＋2 Fe 2 O 3 ＋8CO 2 ↑； ②Na 2 CO 3 ＋Al 2 O 3 2NaAlO 2 ＋CO 2 ↑； ③ Cr 2 O 7 2 － ＋H 2 O 2CrO 4 2 － ＋2H + 根据题意回答下列问题： （1）操作I为 ，固体X中主要含有 （填写化学式）；要检测酸化操作中溶液的pH是否等于4.5，应该使用 （填写仪器或试剂名称）。 （2）酸化步骤用醋酸调节溶液pH<5，其目的是 。 （3）操作Ⅲ有多步组成，获得K 2 Cr 2 O 7 晶体的操作依次是：加入KCl固体、蒸发浓缩、 、过滤、 、干燥。 （4）固体Y中主要含有氢氧化铝，请写出调节溶液的pH=7~8氢氧化铝的离子方程式 。
拍照语音搜题，微信中搜索"皮皮学"使用
参考答案：
参考解析：
知识点：
.
..
皮皮学刷刷变学霸
举一反三
【单选题】It can be inferred from the passage that. when conducting business. one should___________.
A.
put the quality of the product before any other Factors
B.
realize the importance of international trade fairs
C.
employ professional and experienced sales people
D.
cake people's different beliefs into account
查看完整题目与答案
【单选题】When conducting an exit interview, a manager:
A.
should expect employees to be honest as they are leaving the company.
B.
does not need to be as skilled an interviewer as in employment interviews.
C.
needs to use close d -ended questions to control and direct the interview.
D.
starts with routine departure basics, then moves on to why the employee is leaving.
查看完整题目与答案
【单选题】_____ has the currency “ dollar ” .
A.
Australia
B.
Russia
C.
India
D.
SouthKorea
查看完整题目与答案
【单选题】When conducting a test of hypothesis for dependent samples:
A.
the sample size should be at least 30 pairs of observations.
B.
the significance level is more than .05.
C.
the p-value is more than .10.
D.
differences between each matched pair of observations are computed.
查看完整题目与答案
【简答题】电磁式继电器按输入信号不同,可以分为()、()、()、()和()。
查看完整题目与答案
【单选题】继电器按输入信号可以分为( )。
A.
电动式、电压、温度    、时间、速度、压力
B.
电流、电压、触点    、时间、速度、压力
C.
电流、电压、温度    、时间、速度、压力
D.
电流、电压、温度    、时间、瞬时、压力
查看完整题目与答案
【简答题】When conducting yourself in society,what is tact?
查看完整题目与答案
【单选题】With the invasion of the Australian pound, red-feather currency has______.
A.
maintained its value
B.
found increased usage
C.
fallen into disuse
D.
declined in value
查看完整题目与答案
【简答题】根据问句的形式,“有疑而问”的问句可以分为( )、( )、 ( ) 和 ( ) 四类。
查看完整题目与答案
【多选题】When conducting a system review, you need
A.
Screen the retrieved documents
B.
Meta analysis if necessary
C.
Comprehensive collection of all relevant research evidence
D.
Develop literature inclusion and exclusion criteria
查看完整题目与答案
相关题目：
【单选题】It can be inferred from the passage that. when conducting business. one should___________.
A.
put the quality of the product before any other Factors
B.
realize the importance of international trade fairs
C.
employ professional and experienced sales people
D.
cake people's different beliefs into account
查看完整题目与答案
【单选题】When conducting an exit interview, a manager:
A.
should expect employees to be honest as they are leaving the company.
B.
does not need to be as skilled an interviewer as in employment interviews.
C.
needs to use close d -ended questions to control and direct the interview.
D.
starts with routine departure basics, then moves on to why the employee is leaving.
查看完整题目与答案
【单选题】_____ has the currency “ dollar ” .
A.
Australia
B.
Russia
C.
India
D.
SouthKorea
查看完整题目与答案
【单选题】When conducting a test of hypothesis for dependent samples:
A.
the sample size should be at least 30 pairs of observations.
B.
the significance level is more than .05.
C.
the p-value is more than .10.
D.
differences between each matched pair of observations are computed.
查看完整题目与答案
【简答题】电磁式继电器按输入信号不同,可以分为()、()、()、()和()。
查看完整题目与答案
【单选题】继电器按输入信号可以分为( )。
A.
电动式、电压、温度    、时间、速度、压力
B.
电流、电压、触点    、时间、速度、压力
C.
电流、电压、温度    、时间、速度、压力
D.
电流、电压、温度    、时间、瞬时、压力
查看完整题目与答案
【简答题】When conducting yourself in society,what is tact?
查看完整题目与答案
【单选题】With the invasion of the Australian pound, red-feather currency has______.
A.
maintained its value
B.
found increased usage
C.
fallen into disuse
D.
declined in value
查看完整题目与答案
【简答题】根据问句的形式,“有疑而问”的问句可以分为( )、( )、 ( ) 和 ( ) 四类。
查看完整题目与答案
【多选题】When conducting a system review, you need
A.
Screen the retrieved documents
B.
Meta analysis if necessary
C.
Comprehensive collection of all relevant research evidence
D.
Develop literature inclusion and exclusion criteria
查看完整题目与答案