Understanding Chemical Reactions: From Atoms to Acid Rain

HOW DO ATOMS BEHAVE DURING A CHEMICAL REACTION?

Chemical reactions occur when bonds between atoms break and new bonds form, creating a new arrangement of atoms and at least one new substance. Observable changes, such as temperature fluctuations, color changes, gas formation, new solids, and odors, accompany these reactions.

Conservation in Chemical Reactions

Besides energy, mass is also conserved during chemical reactions. Lavoisier's experiment disproving the "phlogiston theory" led to the development of the "law of conservation of mass," which states that matter cannot be created or destroyed in a chemical reaction. Balanced chemical equations represent this law.

Energy and Reactions

Energy is required to initiate reactions. Simply mixing chemicals doesn't guarantee an immediate reaction, as seen with hydrogen and oxygen. Energy sources like heat, electricity, light, or a flame can provide the necessary energy to break bonds in reactants, allowing atoms to rearrange and form new bonds in products.

Exothermic and Endothermic Reactions

Chemical reactions can either release or absorb energy. Exothermic reactions release energy as atoms rearrange, resulting in products with less stored energy than reactants. Endothermic reactions absorb energy, leading to products with more stored energy than reactants.

Applications of Chemical Reactions

Examples of chemical reactions in everyday life include:

• **Ice packs:** The reaction between ammonium nitrate and water absorbs energy, creating a cooling effect.
• **Airbags:** An explosive exothermic reaction rapidly inflates airbags upon impact, releasing nitrogen gas.
• **Acids and Bases:** Acids are corrosive substances with a sour taste, while bases have a bitter taste and feel slippery. They have various applications, from food to cleaning products.
• **Tooth Decay and Antiacids:** Bacteria in the mouth produce acid that can erode tooth enamel. Antiacid tablets can neutralize stomach acid and relieve heartburn.
• **Pickling:** Acids in pickling solutions prevent microorganism growth, preserving food.

Acid Rain and Its Impact

Acid rain forms when sulfur dioxide and nitrogen oxides react with water in the atmosphere. It damages plants and ecosystems, leading to forest decline in some regions.

Acid Rain and Statues

Acid rain reacts with calcium carbonate in marble and limestone, forming gypsum, which gradually erodes statues.

Solutions to Acid Rain

Reducing acidic gas emissions, exploring alternative energy sources, and promoting public transportation can help mitigate acid rain's impact.