Problem 26 - Chemistry: The Central Science

Question

The first stage in corrosion of iron upon exposure to air is oxidation to \(\mathrm{Fe}^{2+} .\) (a) Write a balanced chemical equation to show the reaction of iron with oxygen and protons from acid rain. (b) Would you expect the same sort of reaction to occur with a silver surface? Explain.

Step-by-Step Solution

Answer

(a) The balanced chemical equation for the reaction of iron with oxygen and protons from acid rain is: Fe + O2 + 4H+ -> Fe2+ + 2H2O. (b) The same sort of reaction would not occur with a silver surface because silver has a much lower reactivity with atmospheric oxygen and acid rain than iron. Silver generally doesn't react with these substances and its most common oxidation state is +1.

Step 1: (a) Write the balanced chemical equation

To write the balanced chemical equation for the oxidation of iron to Fe2+ by oxygen and protons from acid rain, we first identify the reactants and products involved in the process. Reactants: iron (Fe), oxygen (O2), and protons (H+) from acid rain Products: Fe2+ ions The oxidation of iron involves the transformation of the metal (Fe) to its ionized version (Fe2+). We also know that in this process, oxygen from the air and protons from acid rain are involved. Therefore, the unbalanced chemical equation will be: Fe + O2 + H+ -> Fe2+ In order to balance the equation, we need to ensure that the atoms of each element are equal on both sides. To do this, we can follow these steps: 1. Balance the O atoms by adding a water molecule to the product side: Fe + O2 + H+ -> Fe2+ + H2O 2. Balance the H atoms by adding two protons (H+) to the reactant side: Fe + O2 + 4H+ -> Fe2+ + 2H2O 3. Check if all the atoms are balanced: Iron: 1 Fe on both sides Oxygen: 2 O on both sides Hydrogen: 4 H on both sides The balanced chemical equation is: Fe + O2 + 4H+ -> Fe2+ + 2H2O

Step 2: (b) Reaction with a silver surface

Let's analyze if the same kind of reaction will happen with a silver (Ag) surface. Silver, like iron, is also a metal and has the capacity to oxidize. However, the rate at which this occurs differs significantly. Silver is known for its very low reactivity when compared to other metals. Silver can be oxidized by a strong oxidizing agent and under certain conditions, but it generally doesn't react with atmospheric oxygen or with protons from acid rain. Its oxidation state in its common compounds is +1, and it would not follow the same process as the one observed in the corrosion of iron. In conclusion, the same sort of reaction would not occur with a silver surface, since silver has a much lower reactivity with atmospheric oxygen and acid rain than iron.