Wednesday, October 22nd , 2014 Objective: to identify acids and bases by ph level. Warmup: 1.) When sugars are broken down to produce usable energy for cells, a large amount of heat is released. Explain how the water inside your cells helps to keep the cell’s temperature constant. Hint: Look at the back of your water packet.

ACIDS AND BASES

acids and bases

(hydrochloric acid added to water produces hydrogen and chlorine) 1. ACID – any substance that gives off hydrogen ions (H+) to a solution. Example: HCl (hydrochloric acid) found in your stomach HCl + H2O  H+ + Cl- reactants products (hydrochloric acid added to water produces hydrogen and chlorine)

(sodium hydroxide added to water produces sodium and more water) BASE 2. BASE – any substance that removes hydrogen ions (H+) from a solution. Does this by adding hydroxide ions (OH-) to H+ to form water (H2O) Example: NaOH (sodium hydroxide) NaOH + H2O  Na+ + H2O reactants products (sodium hydroxide added to water produces sodium and more water)

PH Scale 3. pH SCALE – measure of how acidic or basic a solution is

PH Scale 3. pH SCALE – measure of how acidic or basic a solution is Acids = pH < 7 (more H+ than OH-) Bases = pH > 7 (more OH- than H+) Neutral = pH = 7 (equal amounts of H+ than OH- ) Each pH unit represents a 10x change in concentration of H+ ions Example: pH 2 = 10x more H+ than pH 3 pH 2 = 100x more H+ than pH 4

PH Scale 4. Buffers– substances that cause a solution to resist pH changes Does this by donating/accepting H+ ions Keeps body fluids stable and allows them to maintain homeostasis Example: enzymes can clot blood & break down food white blood cells can make antibodies red blood cells can carry oxygen in the blood