基础化学精品教学（广西医科大学）2013第九章氧化还原electrochemistry.pptVIP

正逆向进行比较，加以说明 * 正逆向进行比较，加以说明， * 非标准状态下，如何判断反应方向？ * * Stronger oxidizing agent: Cu2+ Stronger reducing agent: Sn2+ Direction : from right to left 非标准状态下，如何判断反应方向？ * * So the reaction from left to right is not completely. * * F:faraday常数：96485C·mol-1 * F:faraday常数：96485C·mol-1 * 自学 * 自学 * * 浓度为标准状态可省略 * 121 All alkali metal ions(group 1A) always have a 1+charge, and therefore the alkali metals always have and oxidation number of +1 in their compounds. Similarly, the alkaline earth metals(group 2A ) are always +2, and aluminum(group 3A) is always +3 in their compounds. All alkaline earth metals: +2 In all compounds of aluminum: Al → +3 In writing oxidation numbers, we will write the sign before the number to distinguish them from the actual electronic charges, which we write with the number first * 122the oxidation number of oxygen is usually –2 in both ionic and molecular compounds. The major exception is in compounds called peroxides, which contain the O22- ion, giving each oxygen an oxidation number of –1. The oxidation number of hydrogen is +1 when bonded to nonmetals and –1 when bonded to metals. * 122the oxidation number of oxygen is usually –2 in both ionic and molecular compounds. The major exception is in compounds called peroxides, which contain the O22- ion, giving each oxygen an oxidation number of –1. The oxidation number of hydrogen is +1 when bonded to nonmetals and –1 when bonded to metals. * For example, in the hydronium ion,H30+, the oxidation number of each hydrogen is +1 and that of oxygen is –2. Thus the sum of the oxidation number is 3(+1)+(-2)=+1, which equals the net charge of the ion. This rule is very useful in obtaining the oxidation numbers of the other atoms. * 752 in any redox reaction,both oxidation and reduction must occur. In other words, if one substance is oxidized, then another must be reduced. The substance that makes it possible for another substance to be oxidized is called the oxidizing agent, or oxidant. The oxidizing agen