pH Scale and Solutions Overview

pH Scale and Solutions

• The pH scale measures acidity or basicity of a solution.
• It ranges from 0 to 14.
• A pH of 7 is neutral.
• Lower than 7 is acidic, higher than 7 is basic.
• Acidity corresponds to a higher concentration of hydrogen ions.
• Basicity corresponds to a higher concentration of hydroxide ions.
• The pH scale is logarithmic: each whole number change represents a tenfold change in hydrogen ion concentration.

Using the pH Scale

• Increasing pH by one unit means multiplying the hydrogen ion concentration by 10.
• Decreasing pH by one unit means dividing the hydrogen ion concentration by 10.

pH in Everyday Life

• Soil: Soil pH affects plant growth. Different plants thrive in different pH ranges. Adjusting soil pH is possible via additives (e.g., compost for acidity, calcium oxide for basicity).

• Consumer Products: Many products (shampoo, skincare) are formulated to have a neutral pH. Strong cleaning products often have high hydroxide ion concentrations and are labeled with hazardous warnings.

• Swimming Pools: Pool water pH should be maintained between 7.2 and 7.8. Adjustments are made using acid (to lower pH) or base (sodium carbonate) to maintain proper levels to prevent eye irritation and cloudiness.

Acids

• Acid formulas typically start with "H" and involve water (aq).

• Naming Binary Acids: Start with "hydro," change the anion's suffix from "ide" to "ic," and add "acid." (e.g., Hydrogen Chloride → Hydrochloric Acid)

• Naming Oxyacids: If the anion ends in "ate," use the root and add "ic acid." If it ends in "ite," use the root and add "ous acid." (e.g., Sulfuric acid, Carbonic acid, Nitric acid, Nitrous acid, Phosphoric acid)

• Acid Reactions:

  • Acids React with Metals: Produce hydrogen gas and a salt. (e.g., Hydrochloric acid + Zinc → Hydrogen gas + Zinc Chloride).
  • Acids React with Carbonates: Produce carbon dioxide, water, and a salt. (e.g., Sulfuric acid + iron(III) carbonate → iron(II) sulfate + water + carbon dioxide)

Bases

• Base formulas typically include "OH" and involve water (aq).
• Basic compounds are also called alkaline.
• Naming Bases: Bases are usually ionic compounds composed of hydroxide or carbonate ions, and are named similarly to other ionic compounds (e.g., Sodium hydroxide, Barium hydroxide).

Acid-Base Indicators

• Acid-base indicators change color depending on the acidity or basicity of the solution.
• Examples of natural indicators include red cabbage, beetroot, turmeric, and grape juice.
• Litmus paper is a common indicator. Blue litmus turns red in acids; red litmus turns blue in bases.

Explore the pH scale, measuring acidity and basicity in solutions. This quiz covers the fundamental concepts of pH, its logarithmic nature, and its relevance in everyday life including soil and consumer products. Test your understanding of how pH impacts various chemical environments.