Presentation on theme: "General Chemistry Spring 2010"— Presentation transcript:
1 General Chemistry Spring 2010 ACIDS AND BASES UNIT 10General Chemistry Spring 2010
2 The Importance Of acids… Blood is controlled by buffers Citrus fruits (citric acid)Vinegar (acetic acid)Vitamin C (ascorbic acid)Aspirin (acetyl salicylic acid)Car batteries (sulfuric acid)
3 The Importance Of bases… Baking soda Milk of magnesia Antacids have carbonates, bicarbonates and hydroxides to neutralize acidsAmmonia (cleaning products)Sodium hydroxide, aka: lye (oven and drain cleaner)
4 How do you know you have… An acid?Produces H+ in waterBlue litmus paper turns redSour tasteReacts on metalpH less than 7Metal etched using acid
5 How do you know you have… A base?Produces OH- ions in water (hydroxide ions)Red litmus paper turns blueSlippery feelBitter taste (taste shampoo tomorrow morning)pH higher than 7
6 pH Means “potency of hydrogen” Refers to pondus hydrogenii (potential hydrogen)
8 Arrhenius AcidsSubstance that ionizes in water to produce hydrogen ions (H+)“ionization”- process by which covalent compounds form cations and anionsEx) HCl H Cl-
9 Arrhenius BaseSubstance that dissociates in water to release hydroxide ions (OH-)“dissociation”- process by which ionic compounds separate into ionsEx) NaOH Na OH-
10 Neutralization Reactions An acid neutralizes a base to yield a salt and water.Example A) Hydrochloric acid reacts with sodium hydroxide to give the salt sodium chloride and water.HCl NaOH NaCl H2ODifferent acids yield different salts, but water is always a product
11 Neutralization Reactions Example B) H2SO NaOH Na2SO H2OThe hydrogen ion (H+) from the acid is neutralized by the hydroxide (OH-) ion from the base.These two ions combine to form water.
12 Identifying an Acid and Base Each salt is composed of the cation (+) from the reacting base and the anion (-) from the acid.Predict the acid and base that produce the following salts:Potassium acetate, KC2H3O2Let’s see some steps first.
13 Predicting Acids and Bases Split the salt formula into ionsWhich ion gets H+? Write the formulaWhich ion gets OH-? Write the formulaPotassium acetate, KC2H3O2KOH + HC2H3O2 KC2H3O2 + HOHOPPOSITES ATTRACT!
14 Predicting Acids and Bases Lithium fluoride, LiFHF LiOH Li F H2O
15 The pH Scale Revisited What is pH again? It expresses the acidity of a solution; the concentration of hydrogen ionsRanges from…0 14As pH decreases, the concentration of hydrogen ions increases, and the concentration of hydroxide ions decreases.In a neutral solution, the concentration of hydroxide ions and hydrogen ions are equal.
16 Acid-Base Indicators Methyl Red Color change ~pH 5 Below pH 5: red Above pH 5: yellowAt 5? Orange (only a portion has been converted from yellow to red)
17 Acid-Base Indicators Bromthymol blue Color change ~pH 7 Below pH 7: yellowAbove pH 7: blueAt 7: greenish