Physical Science Chapter 23 Acids and Bases Physical Science Chapter 23

Acids Acid: A substance that produces hydrogen ions in a water solution. The hydrogen ion then interacts with water molecules to form H3O+ ions which are called hydronium ions HCl + H2O  H3O+ + Cl–

Properties of Acids Properties of acids: Taste sour Can cause painful burns Are corrosive May react strongly with certain metals Turns litmus paper red Have a pH less than 7

Bases Base: Any substance that forms hydroxide ions, OH (hydroxide ion), in a water solution In addition, a base is any substance that accepts hydrogen ions (H+) from acids. NH3 + H2O  NH4+ + OH-

Properties of Bases One way to think of bases is that they are opposites of acids Properties of Bases: Most are crystalline solids in pure form Feel slippery Have a bitter taste Strong bases are corrosive and can cause burns Turn litmus paper blue Have a pH greater than 7

pH of a Solution The pH of a solution is a measure of the concentration of H+ ions in it. The pH measures how acidic or basic a solution is. The greater the H+ concentration is, the lower the pH is and the more acidic the solution is.

pH Scale pH Scale ranges from 0 to 14 Less than 7 = Acid Equal to 7 = neutral Greater than 7 = Base 7 INCREASING ACIDITY NEUTRAL BASICITY 14

How to remember what’s what Acid comes before Base in the alphabet Low numbers come before high numbers Acids = low numbers Bases = high numbers

pH of Common Substances pH Scale pH of Common Substances