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问题 实验题

（7分）有一包白色固体样品，可能是碳酸钠、硫酸钡、氢氧化钠、氯化钡中的一种或几种。为探究其成分，小燕老师取用一定量样品，加足量水溶解，过滤得到白色沉淀甲和无色滤液乙。

写出上述操作中可能发生反应的化学方程式：           。

过滤时用到玻璃棒，玻璃棒的作用是          。

【探究活动一】 奋进小组探究白色沉淀甲的成分。

实验操作实验现象结 论
取白色沉淀甲，滴加足量的稀硝酸沉淀部分消失白色沉淀甲中一定含有             
【探究活动二】 智慧小组探究白色固体样品中可能含有       ，设计了如下实验。

实验操作实验现象结论
实验Ⅰ取适量无色滤液乙，加入碳酸钠溶液无明显现象无色滤液乙中一定不含         
实验Ⅱ步骤①：取适量无色滤液乙，加入过量的       溶液，过滤生成白色沉淀原白色固体样品中一定存在该物质
步骤②：取步骤①中的滤液，滴加       溶液       
【反思】 实验Ⅱ中步骤①加入过量试剂的目的是       。

【结论】 通过两个小组的共同探究，得出了原白色固体样品含有的成分。

答案

BaCl2＋Na2CO3＝BaCO3↓＋2NaCl     引流

【探究活动一】BaCO3和BaSO4

【探究活动二】NaOH

实验Ⅰ：BaCl2

实验Ⅱ：步骤①：BaCl2[或Ba(NO3)2或CaCl2或Ca(NO3)2 ]

步骤②：无色酚酞   酚酞溶液变红（或FeCl3，产生红褐色沉淀 …）

【反思】除去滤液中的Na2CO3，排除干扰

题目分析：有一包白色固体样品，可能是碳酸钠、硫酸钡、氢氧化钠、氯化钡中的一种或几种，取用一定量样品，加足量水溶解，过滤得到白色沉淀和无色滤液，沉淀可能使硫酸钡，也可能是碳酸钡，如果是碳酸钡，发生的反应为BaCl2＋Na2CO3＝BaCO3↓＋2NaCl，过滤时用到玻璃棒，玻璃棒的作用是引流，白色沉淀中加稀盐酸，沉淀部分溶解，所以沉淀中既有硫酸钡，也有碳酸钡，可能有氢氧化钠，取适量无色滤液乙，加入碳酸钠溶液，无明显现象，无色滤液乙中一定不含氯化钡，第二个实验室检验氢氧化钠，必须先出去碳酸钠，所以可以加氯化钙，与碳酸钠反应生成碳酸钙和氯化钠，过滤，向滤液中加酚酞，酚酞变红，则溶液中存在氢氧化钠，加过量的氯化钙的目的是出去碳酸钠，防止对氢氧化钠的检验造成影响。

单项选择题

下列程序的运行结果是( )。
#include＜stdio.h＞
main()
static char a[]="Languagef",b[]="programe";
char *p1,*p2;int k;
p1=a;p2=b;
for(k=0;k＜=8;k++)
if(*(p1+k)==*(p2+k))printf("%c",*(p1+k));

A．gae

B．ang

C．program

D．有语法错
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填空题



In the early 1970’s, Citibank of New York City became one of the first financial institutions to install ATM’s on a large scale. Since then, the (1) of automated teller machines has increased dramatically. At the time, the bank hoped (2) their operating costs by replacing human tellers with machines. Little did they (3) that the cash machines would become so successful. However, as more banks added (4) automated service through ATM’s, the machines mushroomed all over the world.
To use an ATM, all you need is a (5) issued by your bank. Your bank may also (6) through a credit card, such as MasterCard or Visa. To begin a (7) , you need to insert the card into an ATM and punch in a personal identification number on the (8) . The personal ID number may consist of (9) and can prevent anyone from using the card.
The ATM next flashes instructions on its (10) for carrying out transaction. To get cash, for example, you are instructed to (11) that indicate whether the money should be withdrawn from a checking or a savings account and the (12) . This request is then displayed on the screen. After you press a button to (13) that the information is correct, the ATM goes to (14) .
How safe, you may ask, is banking by ATM The (15) is meant to prevent anyone, no matter who you are, from using a cash card (16) . If you enter the wrong ID number for a card, a message on the screen will (17) . If you fail to produce the correct number for three times, most machines will (18) .As another precaution against (19) , the bank generally limits the amount that may be withdrawn by cash card (20) , say, to $ 200.
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