Chemical Reactions Activity

Study Notes

Chemical reactions occur due to the reaction between substances, such as magnesium and oxygen in the air.
A chemical reaction can be determined by observing changes in state, color, evolution of gas, or change in temperature.

Chemical equations represent reactants, products, and their physical states symbolically.
Equations must be balanced to ensure the same number of atoms of each type on both reactant and product sides.
Physical states are represented by notations (g), (l), (aq), and (s) for gaseous, liquid, aqueous, and solid states, respectively.
The word "aqueous" is written if the reactant or product is present as a solution in water.

Combination reactions: two or more substances combine to form a new single substance.
Decomposition reactions: a single substance decomposes to give two or more substances.
Exothermic reactions: reactions in which heat is given out along with the products.
Endothermic reactions: reactions in which energy is absorbed.
Displacement reactions: an element displaces another element from its compound.
Double displacement reactions: two different atoms or groups of atoms (ions) are exchanged.
Precipitation reactions: reactions that produce insoluble salts.

Oxidation: the gain of oxygen or loss of hydrogen by substances.
Reduction: the loss of oxygen or gain of hydrogen by substances.
Examples of oxidation and reduction reactions include the reaction of copper and oxygen, and the reaction of copper oxide and hydrogen.