pH-used to measure how acidic or basic a substance is. Determining pH: 1)pH Meter-device used to determine pH of a solution using a voltmeter +2 electrodes..:V  pH 2)Indicators-dyes used to determine pH of a substance. Turns different colors at various pH’s Ex/phenolphthaleinclear  pink pH>7.6 litmusred  blue pH>7 universal red  purple pH 1-14 Acids & Bases

Some natural dyes such as Cabbage Juice can be used as pH indicators. How would you calibrate these colors so if you used Cabbage Juice as an indicator, you would know the pH?

Even in ancient civilizations such as Teotihuacan in A.D., Mesoamericans used natural pigments from the local cactus plant to produce 2 different colored dyes to paint the Pyramid of the Sun, Pyramid of the Moon, and other structures at the site. See:

Arrhenius Definition Acids-contain H that ionizes into H + in water ex/ H 2 SO 4 + 2H 2 O  2H 3 O + + SO 4 -2 ex/ HI monoprotic-HCl, HNO 3, HBr, HI, HC 2 H 3 O 2 diprotic-H 2 CO 3, H 2 SO 4 triprotic-H 3 PO 4 H must be connected to a  electronegative atom Bases-contain OH that dissociates into OH - in water ex/ NaOH  Na + + OH - ex/ Mg(OH) 2 Hydronium H + + H 2 O  H 3 O + H2OH2O H 2 O = HOH.:water is both an acid & base

Bronsted-Lowry Definition Acid-H + donor (loses H + ) Base-H + acceptor (gains H + ) ex/ NH 3 + H 2 O  NH OH - ex/ H 2 CO 3 + OH -  HCO H 2 O baseacidconjugate baseconjugate acid

Strong Acids & Bases-Fully separate(ionize) into ions in water.:Good conductors electricity in water! Ex/ HCl + H 2 O  H 3 O + + Cl - NaOH  Na + + OH - Weak Acids & Bases-Not fully separate(dissociate) into ions in water.:poor conductors electricity in water! Ex/ HC 2 H 3 O 2 + H 2 O  H 3 O + + C 2 H 3 O 2 - NH 4 OH  NH OH -

ex/ Normal CO 2 + H 2 O  H 2 CO 3 pH=5-6 Abnormal NO 2 + H 2 O  HNO 3 pH=3-4 Abnormal SO 2 + H 2 O  H 2 SO 4 pH=3-4 Acid Rain Strong Acid or BaseWeak Acid or Base

Neutralization-Reaction involving an Acid & Base reacting together to produce a Salt & H 2 O pH=7 Ex/ upset stomach? HCl + Mg(OH) 2  MgCl 2 + H 2 O HCl + Ca(OH) 2  CaCl 2 + H 2 O No Acid/Base Properties Ph=7 Buffers-Compounds used to keep pH set at a value. Weak acid + its salt Ex/ lakes, pools, spas, blood H 2 CO 3 + Na 2 CO 3 pH=7.6 Uses of Acids & Bases

Titrations-Scientists use to determine concentration of unknown acidic/basic solution. Use Buret -Uses: neutralization reaction balanced equation standardized solution unknown solution pH=7 equivalence point M acid v acid = M base v base pH=7 Ex/ Concentrated stomach acid? HCl + NaOH  NaCl + H 2 O 32mL 25.3mL ? 1.0mol/L If 1:1 in balanced equation