huaxue 物料守恒质子守恒离子间浓度的大小关系比较具体怎么看?

On Success
We have no idea about when man first bagan to use salt, but we do know that it has been used in many different ways throughout the history. For example, it's recorded in many history books that people who lived three thousand years ago ate salted fish. Thousands of years ago in Egypt, salt was used to preserve the dead. In some period of history, a person who stole salt was thought to have broken the law. Take the eighteenth century for example, if a person was caught stealing salt, he would be thrown into prison. History also records that only in England about ten thousand people were put into prison during that century for stealing salt. About one hundred and fifty years before , if a man took more than his share of salt, he would be thought to have broken the law and would be seriously punished. The offender's ear was cut off. Salt was an important item on the dinner table of a king. It was always placed in front of the king when he sat down to eat. Important guests at the king's table were seated near the salt. Less in important guests were given seats farther away from it.

设CaCl2溶液质量为xg,加入AgNO3溶液质量为yg,氯化钙溶液的溶质质量分数为w.
CaCl2 + 2AgNO3 = Ca(NO3)2 + 2AgCl（沉淀）xw/111 2xw/111
上面化学反应方程式意为：n(CaCl2):n(AgCl)=1:2
而由题意可得：CaCl2溶液质量+AgNO3溶液质量=结束生成溶液质量+AgCl（沉淀）质量
结束生成溶液质量=所加入的硝酸银溶液的质量；
由以上两个关系式可知：CaCl2溶液质量=AgCl（沉淀）质量；
AgCl（沉淀）质量=n(AgCl)乘以M(AgCl)
从而可得：x=(2xw/111)乘以143.5
由此可得：w=0.386,
故CaCl2溶液质量分数为38.6%

你的答案是对的.用原子守恒来解决.NH3的物质的量（a*10负3次方 /22.4 ）=N原子的物质的量,也就是AlN的物质的量.AlN的质量=41a*10负3次方 /22.4（g)

键能低和能量低是不一样的.
键能低说明连接不紧密,当然容易被拆开、重组,也就不稳定.
能量低的话就很难进行反应了.
http://zhidao.baidu.com/question/52091605.html
能量高的东西才容易反应.

选B,Ba(OH)2溶液跟(NH4)2SO4溶液可以产生氨气和硫酸钡沉淀,电石和苏打水,可以产生碳酸钙沉淀和乙炔气体

是的 两个糖分子以а糖苷键缩合而成的双糖.是饴糖的主要成分.由含淀粉酶的麦芽作用于淀粉而制得.用作营养剂,也供配制培养基用.
从化学观点说：麦芽糖（Maltose,or Malt Sugar）是一个化学名词,属双糖(二糖）类.它是白色针状结晶.而常见的麦芽糖是没有结晶,而且在烹调时由于加入了蔗糖,令白色的麦芽糖亦转至为金黄色,增加了它的色香味.麦芽糖的化学式是：C12H22O11
物理性质:白色晶体,易溶于水,有甜味(不及蔗糖).(与蔗糖同分异构)
化学性质:（1）有还原性:能发生银镜反应,是还原性糖.（2）水解反应:产物为2分子葡萄糖
麦芽糖分子结构中有醛基,是具有还原性是一种还原糖.因此可以与银氨溶液发生银镜反应,也可以与新制碱性氢氧化铜反应生成砖红色沉淀.可以在一定条件下水解,生成两分子葡萄糖 .
二.无色或白色晶体,粗制者呈稠厚糖浆状.一分子水的结晶麦芽糖102～103℃熔融并分解.易溶于水,微溶于乙醇.还原性二糖,有醛基反应,能发生银镜反应,也能与班氏试剂（用硫酸铜、碳酸钠或苛性钠、柠檬酸钠等溶液配制）共热生成砖红色氧化亚铜沉淀.能使溴水褪色,被氧化成麦芽糖酸.在稀酸加热或α-葡萄糖苷酶作用下水解成2分子葡葡糖.用作食品、营养剂等.由淀粉水解制取,一般用麦芽中的酶与淀粉糊混合在适宜温度下发酵而得.
麦芽糖可以制成结晶体,用作甜味剂,但甜味只达到蔗糖的1/3.麦芽糖是一种廉价的营养食

在溶液中生成固体离开溶液（沉淀）,不再发生离子反应,所以生成S和I2固体.
具体解法：设消耗Cl2各1mol,则
2KI+Cl2=2KCl+I2 Na2S+Cl2=2NaCl+S 2FeBr2 +3Cl2=2FeCl3+2Br2
2 1 1 1 2/3 1
即6 :3:2

（一）是否生成新物质
（二）物质的分子组成和结构有没有发生改变
常见的化学性质有（ 可燃性、不稳定性、酸性、碱性、氧化性、助燃性、还原性 ）
常见的物理性质有（ 颜色、气味、熔点、沸点、溶解性）
（三）H2 O2 吸收
（四）质量 性质 改变 二氧化锰
（五）D

煤燃烧 化学能转化为内能

（1）n－1
（2）n+3
（3）C80；C160H320
160个共用电子对
每个碳外有四个电子,与另外一个碳共用2对电子即可达到稳定,C::::C,所以160个电子对只需要80个碳

其实挺好想的.
你想,二氯苯中苯环上是四个氢两个氯,把氢和氯的个数倒过来不就是四氯苯的结构了吗,所以它们的同分导构体数相同.