Acids and Bases
Acids and Bases are types of compounds that have characteristic formulas and similar chemical behaviours, especially when they are dissolved in water.
HCl(aq) H+(aq) + Cl-(aq) Acids Acids are substances that release H+ ions in water. For Example, HCl(aq) H+(aq) + Cl-(aq) aq = “aqueous” Which means, “dissolved in water”
NaOH(aq) Na+(aq)+ OH-(aq) Bases Bases are substances that release OH– ions in aqueous solution. For Example, NaOH(aq) Na+(aq)+ OH-(aq)
Properties of Acids and Bases Base (Alkali) Feel Taste Formula Example Wet (no characteristic feel) Slippery Sour Bitter Usually begins with hydrogen HCl –hydrochloric acid H2SO4 – sulfuric acid HC3H5O – lactic acid CH3COOH – acetic acid Most bases contain the hydroxide ion (OH) NaOH – sodium hydroxide KOH – potassium hydroxide NH3OH – ammonia hydroxide K2SO3 – potassium sulfite Vinegar, lemon juice Baking soda, Oven cleaner
Measuring pH pH is measured on a scale from 1 to 14 1 to 7 = Acid (or acidic) 7 to 14 = Base (or basic) pH of 7 (middle of scale) is neutral (like water)
Measuring pH The pH scale is logarithmic which means: a pH of 1 is ten times more acidic than a pH of 2.
pH of some common substances Acid Neutral Base milk - 6.5 coffee – 5 tomatoes – 4 cola drinks – 3 stomach acid – 2 pure water – 7 blood - 7.5 sea water – 8 detergent – 10 household cleaners – 11 oven cleaners – 14
pH of substances can be measured using pH indicators. pH paper Universal Indicator Natural indicators
pH paper www.explorelearning.com
Universal Indicator
Natural Indicators
Acid + Base Salt + Water Neutralization Acids and bases mix to form a salt and water Acid + Base Salt + Water General Formula: HxA + B(OH)y AB + H2O produces H+ ions produces OH- ions Lots of types HOH (aka H2O)
Neutralization Examples: Hydrochloric acid + Sodium hydroxide Sodium chloride + Water HCl + NaOH NaCl + H2O Nitric acid + Calcium hydroxide Calcium nitrate + water 2HNO3 + Ca(OH)2 Ca(NO3)2 + 2H2O
Homework Answer pg. 271 #2-6, 8 Read pg. 272-275 Answer pg. 275 #2-5