妙用“等化合价法则”解题

• 作 者: 胡宗华
• 出 处: 考试(中考版)
• 发表日期: 2004年10期
• 关键词: 金属氧化物 相对原子质量 氧元素 值相等 铝元素 巩固练习 硫元素 李斗 镁元素 磷酸根

根据“在化合物理,正负化合价的代数和为零”,我们可推出“在化合物里,正化合价代数和与负化合价代数和的数值相等”这一等化合价法则。巧妙运用此法则,会给解题带来意想不到的方便。例1 某金属M的氧化物与还原剂反应后可得金属M,此时质量减少了50.5%,M的相对原子质量为55,则该金属氧化物的化学式为____ 解析:金属M的氧化物被还原剂还原为M后,质量减少了50.5%,说明在该金属氧化物中,氧元素的质量分数为50.5%。此题若根据化学式来计算,可设该金属氧化物的

According to “in compound theory, the algebraic sum of the positive and negative valences is zero,” we can derive the equal valence rule that is “in the compound, the valences of the positive valences and the sums of the algebraic sums of the negative valences are equal”. Clever use of this rule will bring unforeseen convenience to the problem solving. Example 1 Metal M can be obtained by reacting the oxide of a certain metal M with a reducing agent. At this time, the mass is reduced by 50.5%. The relative atomic mass of M is 55. The chemical formula of the metal oxide is ____. Analysis: oxidation of metal M After the material was reduced to M by reduction agent, the mass was reduced by 50.5%, indicating that the mass fraction of oxygen in the metal oxide was 50.5%. If this question is calculated according to the chemical formula, the metal oxide can be set