occur when substances undergo changes in their composition.

is a process in which one of new substances called reactants is converted to a new set of substance called products.

A chemical reaction’s manifestations may be often be detected through the following:

is due to chemical reaction

plays an important role in chemical change

is always involved in chemical reaction; it is either given up ot absorbed

The atoms of the substances rearrange but the total number of atoms remains the same after the reaction.

The original substances lose their identities and can no longer be recognized in the newly formed products.

Energy is involved in the chemical reaction. Heat is either absorbed or released.

The total mass of the reactants is equal to the total mass of the products.

reaction type

two or more compounds combine to form one compound

the opposite of a combination reaction - a complex molecule breaks down to make simpler ones

two solutions of soluble salts are mixed, resulting in an insoluble solid (precipitate) forming

an acid and. base reaction with each other. Generally, the product of this reaction is a sal and water

oxygen combines with a compound to form carbon dioxide and water. These reactions are exothermic, meaning they give off heat

one element trades places with another element in the compound

is conserved in chemical reactions

the total ___ of the system is the same before and after a reaction

is cooler than surroundings

is hotter than surroundings

is the sum of the internal energy. and pressure times volume. We cannot measure the ____ of a system, but we can look at changes in it. (denoted by H)

is used to determine the amount of disorder in a closed system. We have a closed system if no energy from an outside source can enter the system. (denoted by S)

is the symbolic representation of chemical reactions.