Corrosion of Metals

Corrosion

• Iron articles are shiny when new but get coated with a reddish brown powder when left for some time, a process known as rusting.
• Corrosion occurs when a metal is attacked by substances around it such as moisture, acids, etc.
• Examples of corrosion include the black coating on silver and the green coating on copper.
• Corrosion causes damage to metal objects such as car bodies, bridges, iron railings, ships, and more.
• Iron corrosion is a serious problem, resulting in enormous annual spending to replace damaged iron.

Rancidity

• Fats and oils become rancid when oxidized, changing their smell and taste.
• Antioxidants are added to food to prevent oxidation, slowing down the rancidity process.
• Keeping food in air-tight containers also helps slow down oxidation.
• Manufacturers use techniques like flushing bags with nitrogen to prevent oxidation, such as in chip production.

Life Processes

• Life processes are the maintenance functions that occur in living organisms, even when they are not actively doing anything.
• These processes are necessary to prevent damage and breakdown and require energy from outside the body.

Nutrition

• Energy is obtained from outside the body through food, which is primarily carbon-based.
• Nutrition is the process of transferring energy from outside the body to the inside.

Growth and Energy

• For growth, additional raw materials are needed from outside the body.
• The energy obtained from outside sources needs to be broken down or built up and converted into a uniform source of energy for the body.
• Chemical reactions, including oxidising-reducing reactions, are necessary to break down molecules.

Respiration

• Respiration is the process of acquiring oxygen from outside the body and using it to break down food sources for cellular needs.

Complexity and Specialization

• In multi-cellular organisms, not all cells are in direct contact with the environment, making simple diffusion insufficient.
• Specialized tissues develop to perform specific functions, including uptake of food and oxygen, transportation, and excretion.

Transportation

• A transportation system is needed to carry food and oxygen from one place to another in the body.
• This system also transports waste away from cells to excretory tissues.

Excretion

• Excretion is the process of removing waste by-products from the body, which are harmful if not discarded.
• Specialized tissues for excretion develop in multi-cellular organisms.