初中化学九年级上册 4.5 化学方程式“黄冈杯”一等奖

4.5化学方程式假如你是长征系列火箭推进器的设计师，已知火箭升空至少要携带100kg的液氢，充分燃烧才能获得足够的能量。你会在火箭助燃仓中填充多少千克的液氧来满足这些液氢的完全燃烧？

我会思考“神舟十号”升空1、能正确书写简单的化学反应方程式,并在理解化学方程式涵义的基础上，掌握有关反应物、生成物质量的简单计算。2、掌握化学方程式计算的书写格式，同时培养、提高思维能力和解题能力。3.认识定量研究对于化学科学发展的重大作用及体验化学学科对实际生产生活有重要的意义。学习重点学习目标1、掌握已知一种反应物（或生成物）的质量，求生成物（或反应物）的质量。2、根据化学方程式计算的书写格式规范化。以镁在空气中燃烧为例说明化学方程式的涵义。镁在空气中燃烧反应中反应物与生成物之间的质量比可表示为：2Mg+O2======2MgO

2×24：16×2：（24+16）×2

48：32：

80若：48克：（）克：（）

克点燃若：（）克：（）克：40

克32802416温故知新说明：在化学反应中，反应物与生成物之间的质量比是成正比例关系。因此，利用正比例关系根据化学方程式和已知的一种反应（或生成物）的质量，可求生成物（反应物）。加热分解31·6g高锰酸钾,可以得到多少克氧气?

步骤:1、设未知量解：设可以得到氧气的质量为X2、写出反应的化学方程式并配平KMnO4=K2MnO4+MnO2+O22

3、找出相关物质写出相对分子质量和系数的乘积、已知量、未知量

4、列比例式

6、简明地写出答案5、求未知数典例精析解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X解：设可以得到氧气的质量为X3163231·6gx答:可以得到0.6克氧气3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g答:可以得到0.6克氧气x3231·6g答:可以得到0.6克氧气x3231·6g316答:可以得到0.6克氧气X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx答:可以得到0.6克氧气3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g答:可以得到0.6克氧气x3231·6g答:可以得到0.6克氧气x3231·6g316答:可以得到0.6克氧气X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx答:可以得到0.6克氧气3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g答:可以得到0.6克氧气x3231·6g答:可以得到0.6克氧气x3231·6g316答:可以得到0.6克氧气X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx3163231·6gx3231·6g31·6g31·6g31·6g3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6gx3231·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gxKMnO4=K2MnO4+MnO2+O22解：设可以得到氧气的质量为X31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gX=3.2gx31·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx31·6gx31·6g31·6g31·6g31·6g31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6gx31·6g316X=3.2gx3231·6g316=3231.6gx316=3231.6gx316=3231.6gx316=3231.6gx须带单位不带单位

⑴化学方程式要配平，注意标明反应条件、气体和沉淀符号。

⑵相关物质的相对分子质量写在相应化学式下面，一定

要注意用相对分子质量乘以化学式前面的系数，已知量和未知量写在相应相对分子质量下边。

⑶计算结果按题目中的要求；若题中没有要求，一般保留一位小数。⑷代入化学方程式计算的量必须是纯净物的质量,若是不纯物,则需转换；若为气体体积,则将其换算成气体质量。注意事项15.5克红磷在氧气中充分燃烧,可生成五氧化二磷多少克?解:设可生成X克五氧化二磷点燃P+O2=