Chemical change

Chemical change

make sure you have a notebook next to you and sign in on your phone

that is climate change

• A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed. It results when a substance combines with another to form a new substance (synthesis or either decomposes to form more substances).

• Combining baking soda and vinegar (which bubbles off carbon dioxide gas) Combining any acid with any base. Cooking an egg. Burning a candle. Rusting iron. Adding heat to hydrogen and oxygen (produces water) Digesting food. Pouring peroxide on a wound.

A chemical change, also known as a chemical reaction, is a process in which one or more substances are altered into one or more new and different substances. In other words, a chemical change is a chemical reaction involving the rearrangement of atoms.

While a physical change can often be reversed, a chemical change typically cannot be, except through more chemical reactions. When a chemical change occurs, there is also a change in the energy of the system. A chemical change that gives off heat is called an exothermic reaction. One that absorbs heat is called an endothermic reaction.

Chemists recognize three categories of chemical changes: inorganic chemical changes, organic chemical changes, and biochemical change.

Inorganic chemical changes are chemical reactions that don't generally involve the element carbon. Examples of inorganic changes including mixing acids and bases, oxidation (including combustion), and redox reactions.

Organic chemical changes are those that involve organic compounds (containing carbon and hydrogen). Examples include crude oil cracking, polymerization, methylation, and halogenation.

Biochemical changes are organic chemical changes that occur in living organisms. These reactions are controlled by enzymes and hormones. Examples of biochemical changes include fermentation, the Krebs cycle, nitrogen fixation, photosynthesis, and digestion.

A calorimeter is a device used to measure the heat flow of a chemical reaction or physical change. The process of measuring this heat is called calorimetry. A basic calorimeter consists of a metal container of water above a combustion chamber, in which a thermometer is used to measure the change in water temperature. However, there are many types of more complex calorimeters.

The basic principle is that heat released by the combustion chamber increases the temperature of the water in a measurable way. The temperature change may then be used to calculate the enthalpy change per mole of substance A when substances A and B are reacted.

The equation used is:

q = Cv(Tf - Ti )

where:

q is the amount of heat in joules