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Chapter 7. Acids & Bases. About Acids…. Sour taste Neutralize base Dissolves active metal Litmus indicator = red Definitions Arrhenius: form H + in water Bronsted-Lowry: donates a proton. About Bases…. Bitter taste Neutralize acid Feels slippery or “soapy” Litmus indicator = blue
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Chapter 7 Acids & Bases
About Acids… • Sour taste • Neutralize base • Dissolves active metal • Litmus indicator = red • Definitions • Arrhenius: form H+ in water • Bronsted-Lowry: donates a proton
About Bases… • Bitter taste • Neutralize acid • Feels slippery or “soapy” • Litmus indicator = blue • Definitions • Arrhenius: form OH- in water • Bronsted-Lowry: accepts a proton
Strong Acids & Bases • Come apart completely in water • Examples: Hydrochloric acid, sulfuric acid, nitric acid
Weak Acids & Bases • Come apart only partially in water • Examples: acetic acid, carbonic acid, hydrocyanic acid
Acid/Base Neutralization (Titration) • Strong acid + strong base HCl + NaOH H2O + NaCl NaCl H+ Cl- Na+ OH- H2O
pH Calculations pH = – log [H+] [H+] = 10-pH • What is the pH of a solution that has a hydrogen ion concentration of 8.5 x 10-4M? • If a solution has a pH of 9.4, what is the hydrogen ion concentration?
Acids & You • Acid rain Source: http://www.newint.org/issue114/rain.htm
Acids & You • Digestion ~ 2 liters of stomach acid per day! Source: http://www.solvaypharma.ca/en/areas/gastro2.asp
Acids & You • In your car Source: http://newark.rutgers.edu/~huskey/images/lead-acid-battery.gif
Bases & You • Cleaning • Clarifying shampoos • Higher pH than the hair itself makes the hair shaft swell and allows cleaning agents to penetrate more deeply • Detergents • Break up oil and grease • Drain cleaner • Very high pH to eat through acidic hair & skin debris
Bases & You • Antacids • Acid-base neutralization • Calcium carbonate + stomach acid
Bases & You • Baking • Baking soda & baking powder react with acid in the batter to form bubbles of CO2 Source: http://www.joyofbaking.com/bakingsoda.html
Practice Nitric acid (HNO3) reacts with magnesium hydroxide in an acid-base neutralization reaction. Write the balanced equation. Name both products in the reaction. 2HNO3 + Mg(OH)2 2H2O + Mg(NO3)2 Water and magnesium nitrate
Practice What is the molarity? 50.0g of potassium bromate dissolved in enough water to make 1.5L of solution (2 decimal places) How many grams to weigh out? Make 1.8L of a 0.75M solution of calcium perchlorate (2 decimal places) 0.2M 322.52g
Practice What is the percent concentration? (1 decimal place) 45mL of ethanol dissolved in 1L of water 85g of NaCl dissolved in 315g of water 4.5% v/v 21.3% m/m
Practice How many times more acidic is lemon juice (pH 1.5) than blood (pH 7.5)? Something that is 10,000 times more basic than tomatoes (pH 4.2) would have a pH of what? 1,000,000 or 106 times more acidic pH of 8.2
Practice What is the pH? (2 decimal places) [H+] = 1.87 x 10-4 M What is the hydrogen ion concentration? pH = 11.45 3.73 3.55 x 10-12 M