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Acids and Bases http://www.emsb.qc.ca/laurenhill/science/bronsted_cartoo n.gif Why are they important? •They are found on the Earth you walk, the foods you eat and the products that you, not to mention who important your amino acids are •These two flowers are the same species. Why are the different colors? •Their color depends on the acidity of the soil that they are grown in http://www.profizahrada.cz/images_data/3170-hydrangea-macrophylla-bailmer-1.jpg Taste The pH Scale • • • • The measurement of H+ (acid) pOH = measure of OH-(base) ions. Lots of H+ = Acid Lots of OH- = Base pH + pOH = 14 • What is the pH of a solution that has a pOH of 9? – Substute in • pH + • pH = 5 9 = 14 Think you’ve got it? The Basic Formula • Acid + Base Salt + Water HA + BOH BA + H2O • What is a salt again? – General way to describe an ionic bond • Acid and base reactions can happen forward and backwards Acids • contain H+ (proton) • Sour in taste • Strong Vs. Weak – Strong = pH 1-4 (molecule will break apart) – Weak = pH 3-6 ( only some molecule will) • Example: – HCl H+ + Cl- Bases • Contain OH• Alkaline • Strong Vs. Weak – Strong = pH 10-14 – Weak = pH 8-10 (only some break apart) Neutral • pH = 7 • Neutraization – When acids and bases are mixed • Antacid – Stomach acid + antacid = neutralized stomach – Let’s visit The Alien Juice Bar BAAD Acronym • Bases Accept protons (H+) • Acids Donate protons(H+) Progress Check Solution stoichiometry • Concentration • [ } = concentration in moles/ liter pH = -log [H+] pH scale • Reactions with solution Neutralization reaction 10.0 ml of 1.5 M HCl solution neutralizes a 30.0 ml sample Ca(OH)2. What is the concentration (M) of the Ca(OH)2 solution? • First step = Balance the Equation • 2 HCl + Ca(OH)2 CaCl2 + 2H2O • Next start w/ given and follow units until unknown .01 L x 1.5 M HCl x 1L = .0075M Ca(OH)2 * .0075 M Ca(OH)2 .03L = 1 moles Ca(OH)2 2 moles HCl .25M 15.9 ml of 2.50M Al(OH)3 solution is used to neutralized a 25.0 ml sample of H2SO4 . Calculate the molarity of H2SO4 Solution. • First, balance the equation • 2Al(OH)3 + 3H2SO4 Al2(SO4)3 + 6H2O • Next, start w/ given and follow units until unknown • .159L x 2.50moles Al(OH)2 x 3 moles H2SO4 1L 2moles Al(OH)2 = .6M H2SO4 • .6 M H2SO4 = .025L 24M Indicators • Indicates pH • Change colors at different pH Levels • Types – Universal – Phenolphthalein Clear Pink Magenta * For our lab we went to stop at pink Cabbage Indicator pH calculations • pH = measure of H Buffers • Resist change to pH • Example – Holding your breath will build up the concentration of CO2 in your body. – That changes the pH in your blood – Exhaling the CO2 changes the pH back to normal