Acids, Bases, and pH

Beyond Water Acids, Bases, The Water Molecule As we previously discussed, a molecule of water consists of one atom of Oxygen and two atoms of Hydrogen. H2O! But Sometimes a water molecule can react to form ions (positively or negatively charged atoms or

molecules) The Ions A molecule of water can ionize into H+ and OH- ions. H+ a Hydrogen Ion We call OH- a Hydroxide Ion We call The concentration of these ions make something

either an acid or a base! The pH Scale The pH scale is a measurement system that indicates the concentration of H+ ions in a solution. The scale ranges from 0-14 7 is neutral 0-6 is acidic 8-14 is basic (also called alkaline)

How is this pH scale connected to Water? Acidic substances have more H+ ions than OH- ions. In fact, the more H+ ions a solution has, the more acidic it is! Basic (alkaline) substances have more OH- ions than H+ ions. How to Read the pH Scale Start at 7, which is neutral.

The lower the pH number, the stronger the acid The higher the pH number, the more basic the substance is. Each step on the pH scale represents a factor of 10 For example, a solution with a pH of 4 has 1ox as many H+ ions as a solution with a pH of 5 How to read the pH Scale Questions for you:

A liter of solution with a pH of 4 has how many times more H+ ions than a liter of solution with a pH of 6? A substance with a pH of 10 has more _____________ ions than a substance with a pH of 5. Acids An acid is an compound that forms H+ ions in solution Acidic solutions contain higher concentrations of H+

ions than pure water and have pH values below 7. Strong acids have pH values below 3 Question: A substance with a pH of 6 is considered a) An acid b) A Base c) Neither an acid nor a base d) Both an acid and a base Bases A base is a compound that produces

Hydroxide (OH-) Ions in solution. Basic, or alkaline, solutions contain lower concentrations of H+ ions than pure water and have pH values above 7. Strong bases have a pH above 11. Buffers Remember the characteristic of living things that states that living things keep their internal conditions stable

(homeostasis)? Well this goes for pH too! The pH of fluids in the human body is kept between 6.5 and 7.5 If the pH is lower or higher than that, it will affect the chemical reactions that need to take place in your cells! One of the ways that the body controls pH is through dissolved compounds called Buffers. Buffers are weak acids or bases that can react with stronger acids and bases to prevent sharp, sudden

changes in pH.