Phenomena can be observed in all the sciences. Biology and chemistry are no exceptions. Have you ever wondered how fire burns or food rots? Many of these processes are redox reactions. Redox is a type of reaction in which atoms have an increase or decrease in electrons. Let's look at some of these processes in more detail.
Have you ever seen old metal become reddish-brown? That is called rust. Rust is an oxide. It is formed by the reaction of oxygen, iron, and moisture. With enough time, iron can completely turn into rust. Iron near salt water rusts quicker. You see many rusty structures near the sea!
One phenomena that everyone knows is fire. Fire is the oxidation of a material. In order for a material to catch alight, a process called combustion happens. Most forms of combustion happen when gas oxygen joins with another substance. For example, wood burns when oxygen in the air joins with carbon in the wood.
Combustion begins when a material reaches its ignition point. Every material ignites at a different temperature. This temperature can be reached by being heated, from a spark, or even from strong light. During this process, heat and light are released. That is what we see when something is burning!
The human body is home to many redox reactions. Metabolism is a group of reactions that break down food. Digestion is included in this group. When we eat, food is converted into energy. The glucose in food mixes with oxygen, causing it to break down. This process is called cellular respiration, or aerobic respiration, as it requires air.
Cells must adapt to different conditions. Cells can also get energy where there is no air. The process is called anaerobic respiration. Food is still broken down, but it is not as efficient as when oxygen is used.
Most living matter on Earth is made up of carbon, hydrogen, and oxygen. When a living organism dies, it begins to react with oxygen in the air. This causes the body to decay. The body will disappear after a period of time.
It is not just oxygen that causes things to decompose. Often, the process is helped by animals such as worms. They help break down dead organisms and turn them into simpler materials. These materials then go back into the Earth, helping things grow again.
For many years, humans have been finding ways to delay decomposition. Through a process called embalming, bodies can be preserved for many years. This allows bodies to be shown in ceremonies or to be preserved for medical purposes.
The history of embalming is long. Some ancient cultures, such as the ancient Egyptians, learned how to preserve bodies around 5,000 years ago. They would remove the organs, rid the body of any moisture, and cover the body in a mixture called natron. They did this because they believed that the soul could return to the preserved body after death. Now, the process is different. Liquids and salts are used to ensure bodies are kept in good condition.
We do not have to look far to find interesting things that happen in our world. What reactions do you see around you?