Acids, Bases, and pH Flashcards

Grade 7 · Science · Flashcards

Essential vocabulary for acids, bases, the pH scale, indicators, and neutralization reactions.

Flashcards

Acid: Substance that releases H⁺ ions in solution; pH below 7; sour taste; corrodes metals.
Base (alkali): Substance that accepts H⁺ or releases OH⁻; pH above 7; bitter taste; slippery feel.
pH scale: Logarithmic scale from 0 to 14 measuring acidity (0–6), neutrality (7), or alkalinity (8–14).
Neutral solution: A solution with pH = 7; equal concentrations of H⁺ and OH⁻. Example: pure water.
Neutralization: Reaction between an acid and base producing a salt and water; both are neutralized.
Salt: An ionic compound formed in a neutralization reaction between an acid and a base.
Indicator: A chemical that changes color to show whether a solution is acidic or basic (e.g., litmus).
Litmus paper: Red litmus turns blue in bases; blue litmus turns red in acids.
Hydrochloric acid (HCl): Strong acid found in your stomach that helps digest food and kill bacteria.
Sodium hydroxide (NaOH): Strong base used in drain cleaners; also called lye or caustic soda.
Logarithmic scale: A scale where each unit represents a 10× change (pH 4 is 10× more acidic than pH 5).
Hydrogen ion (H⁺): A positively charged ion (proton) released by acids in water solution.
Hydroxide ion (OH⁻): A negatively charged ion released by bases; combines with H⁺ to form water.
Antacid: A basic substance (like calcium carbonate) that neutralizes excess stomach acid.