June 27, 2025

Amy Nangia 

12th Grade

Michael E. DeBakey High School for Medical Professions 

Acids and Bases: The Chemistry Behind Everyday Life

Acids and bases are central to chemistry and life itself. Whether it's the sour taste of lemon juice, the fizz in soda, or the effectiveness of your cleaning spray, acids and bases are the substances working behind the scenes to make things work. Chemically speaking, acids are substances that release hydrogen ions (H⁺) in a solution, while bases release hydroxide ions (OH⁻). Scientists measure their strength using the pH scale, which ranges from 0 (most acidic) to 14 (most basic), with 7 being neutral.

There are multiple ways to define acids and bases:

1. The Arrhenius Model: Acids produce H⁺, and bases produce OH⁻ in water.

2. The Brønsted-Lowry Theory: Acids donate protons (H⁺), and bases accept them.

3. The Lewis Theory: Acids accept electron pairs, and bases donate them.

A Brief History of Acids and Bases

The story of acids and bases goes back to ancient civilizations. At the time, people used vinegar to preserve food and lye (an alkaline solution) to make soap. In the 17th century, Robert Boyle started distinguishing acidic and basic substances. The real turning point came in the late 1800s when Swedish chemist Svante Arrhenius proposed a formal definition for them. Later, Johannes Brønsted and Thomas Lowry added a more general idea of proton transfer, followed by Gilbert Lewis, who introduced electron interactions. These evolving theories allowed chemists to better understand reactions at the molecular level and paved the way for modern chemical and biological research.

Everyday Applications

Acids and bases play essential roles in our daily routines—even if we don’t always realize it.

In the kitchen, citric acid in lemons, acetic acid in vinegar, and carbonic acid in soda provide flavor and preserve food. When baking, recipes often call for a base such as baking soda (sodium bicarbonate) and an acid like cream of tartar or buttermilk. Their reaction creates carbon dioxide gas, which helps the dough rise.

In personal care, shampoos, soaps, and skin products are formulated to match the body’s natural pH. Our skin is slightly acidic, so overly basic products can irritate or dry it out. Many facial cleansers advertise being "pH-balanced" to maintain healthy skin.

In cleaning, bases like ammonia and bleach break down grease and stains, while acids like citric acid remove rust and hard water deposits. Toilet bowl cleaners, for example, are often highly acidic to break down mineral buildup quickly.

Industrial and Scientific Importance

In the industrial world, acids and bases are not only common—they’re essential.

Acids like sulfuric acid (H₂SO₄) are produced on a massive scale to make fertilizers, process metals, and refine petroleum. Nitric acid is used to manufacture explosives and dyes. Hydrochloric acid helps clean metal surfaces before welding and is used in the production of PVC plastic.

Bases like sodium hydroxide (NaOH), or lye, are used to make soap, paper, textiles, and drain cleaners. Ammonia (NH₃), a base, is a key ingredient in fertilizers and refrigeration systems.

Laboratory work also depends on pH. Titrations are used to determine the concentration of acidic or basic solutions. pH indicators like litmus paper, phenolphthalein, or digital probes are vital tools in classrooms and industrial quality control labs alike.

Biological Significance

Acids and bases are crucial for living organisms, especially humans.

In the human body, enzymes only function properly within specific pH ranges. For instance, pepsin, a digestive enzyme in the stomach, requires a highly acidic environment (pH 1.5–2) to break down proteins. The stomach produces hydrochloric acid for this purpose. Once food moves into the small intestine, the pancreas releases a base (bicarbonate) to neutralize the acid, protecting the intestine and allowing other enzymes to function.

In blood, the pH must stay between 7.35 and 7.45. If it strays too far from this range, it can lead to dangerous health conditions like acidosis or alkalosis. The body uses buffer systems—combinations of weak acids and bases—to stabilize blood pH. One key example is the bicarbonate buffer system, which helps maintain homeostasis during respiration.

In plants, soil pH affects nutrient availability. If the soil is too acidic or too basic, plants can't absorb essential nutrients like nitrogen or phosphorus effectively. Farmers and gardeners often add lime (a base) or sulfur (which increases acidity) to adjust soil pH for optimal crop growth.

The Future of Acids and Bases

As science advances, the role of acids and bases is growing in innovation. One exciting area is green chemistry, which uses safer acids and bases in place of toxic chemicals. For example, citric acid is replacing stronger acids in cleaning products for eco-friendly alternatives. In medicine, pH-sensitive drug capsules are being developed to release medicine only in specific parts of the digestive tract.

In agriculture, researchers are exploring ways to manage soil pH without harming the environment. Meanwhile, in industry, acid- and base-catalyzed reactions are being optimized to reduce waste and improve energy efficiency.