Tag: chemistry

Architectural structures built with copper corrode to give green verdigris (copper carbonate). It can be a mixture of carbonate and sulfate compounds in various amounts, depending upon environmental conditions such as sulfur-containing acid rain.

The hydrogen ions and the dissolved gases such as carbon dioxide and water catalyze the rusting of iron.
Certain impurities also catalyze the rusting of iron.

If two metals are made to touch under the surface of an electrolyte they constitute a short circuited cell. Corrosion is a greater problem in winter when the salts are laided as chromium and iron are the two metals and NaCl act as an electrolyte.

Rusting of iron is corrosion of iron. Rusting of iron takes place when iron corrodes in the presence of water and oxygen. It is a redox reaction whereby oxygen acts as an oxidising agent while iron acts as a reducing agent. When iron is contact with water, a simple chemical cell is formed.

Phosphoric acid will not form a protective coating of iron oxide on the surface of iron. A strong oxidizing agent such as nitric acid is required for this process.

• One of the properties of iron is that it reacts with oxygen in the presence of moisture and gets corroded by forming rust.
• Air contains oxygen and moisture. Hence, iron readily rust when exposed to air.
• Steel (stainless steel, not mild steel) is an alloy of iron having the property to resist corrosion including rusting. Hence, stainless steel, though it contains iron, does not undergo corrosion. 

In cathodic protection, the more easily oxidized metal is attached to the metal which is to be protected. This results in corrosion of more easily oxidized metal. The other metal is thus protected from corrosion.

In the activity series, metals are on the top of the series react and corrode easily as these metals are highly reactive like iron corrodes easily in the presence of water and air forming its oxide layer while metals present at the bottom are least reactive and do not corrode easily like gold, silver and platinum are some of them.

If edible oil is allowed to stand for a long time in an iron or tin container the fatty acids in the oil react with rust flakes or powder to form salts. These salts contaminate the oil and hence the oil becomes rancid. Thus the above statement is true.

'X' is copper (Cu) and the black-coloured compound formed is copper oxide(CuO). The equation of the reaction involved on heating copper is given below: