Chemical Reactions Activity

Chemical Reactions

• 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

• 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.

Types of Chemical Reactions

• 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 and Reduction

• 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.