Metalworking oxidation is one of the main reasons that gold is found in nuggets. These nuggets are relatively pure gold and are workable as they are found. Copper ore, being relatively abundant, and tin ore became the next important players in the story of metalworking. Using heat to smelt copper from ore, a great deal of copper was produced. It was used for both jewelry and simple tools. However, copper by itself was too soft for tools requiring edges and stiffness. At some point tin was added into the molten copper and bronze was born. Bronze is an alloy of copper
Tin(II) chloride to maintain the equilibrium towards the left-hand side (using Le Chatelier's principle). Solutions of SnCl are also unstable towards oxidation by the air: This can be prevented by storing the solution over lumps of tin metal. There are many such cases where tin(II) chloride acts as a reducing agent, reducing silver and gold salts to the metal, and iron(III) salts to iron(II), for example: It also reduces copper(II) to copper(I). Solutions of tin(II) chloride can also serve simply as a source of Sn ions, which can form other tin(II) compounds via precipitation reactions. For example, reaction with sodium sulfide produces