TEAS® Science Study Guide
Solutions, Acids and Bases
Solutions
A solution forms when a solute dissolves in a solvent (salt dissolving in water: salt is the solute, water the solvent). Water is called the "universal solvent" because it dissolves so many substances.
The pH scale
pH runs from 0 to 14 and measures how acidic or basic a solution is.
- 0–6.9 — Acidic (high concentration of H⁺ ions). Examples: lemon juice, stomach acid.
- 7 — Neutral. Pure water.
- 7.1–14 — Basic/alkaline (high concentration of OH⁻ ions). Examples: soap, bleach.
The scale is logarithmic — each whole step is a tenfold change. A pH of 4 is ten times more acidic than a pH of 5, and a hundred times more acidic than a pH of 6.
Acids vs. bases
- Acids release hydrogen ions (H⁺) and have a low pH.
- Bases release hydroxide ions (OH⁻) and have a high pH.
Terms to know
- Solute — What dissolves. Solvent — What does the dissolving.
- pH — A measure of acidity or basicity.
- Acid — Low pH, donates H⁺. Base — High pH, produces OH⁻.
What the TEAS asks most
- In salt water, what is the solvent? Water.
- What pH is neutral? 7.
- Is a pH of 3 acidic or basic? Acidic.
- How much more acidic is pH 4 than pH 6? 100 times.