Strength of Acids & Bases Acid and base strength is measured on the pH scale: pH ranges from 0-14 (typically) pH less than 7 is acidic pH greater than 7 is basic pH equal to 7 is neutral test Stronger acid Stronger base See page 3 of data booklet.

Each decrease of 1 on the pH scale is 10x more acidic e.g. pH 4 is times more acidic than pH 5 10 pH 3 is times more acidic than pH 6 1000 pH 2 is times more acidic than pH 7 100000 Using p. 222 of your textbook, how much more acidic are… lemons than tomatoes? Stomach acid than bananas? 100 x 10000 x

Note: Square brackets [ ] is concentration As pH goes up, [H+] goes down As pH goes up, [OH-] goes up As [H+] goes up, [OH-] goes down Refer to diagram on data booklet.

Naming Acids Some common acid names are in your data booklet (p5) How do you name the rest?

Jigsaw Activity Form 3 groups Each group will become an expert in 1 way to name acids Learn the rules from index card Practice within group with questions Mix up groups and teach others

Hydro, -IC or -OUS? If the anion name ends in -ide: the acid name starts with hydro and ends with -ic acid. eg: HCl: Cl- is chloride. So HCl is hydrochloric acid. If the anion name ends in -ate: the acid name ends with -ic acid; no hydro- prefix. eg: HNO3: NO3- is nitrate. So HNO3 is nitric acid. Hydrogen bromide – hydrobromic acid Hydrogen Sulfate – sulfuric acid or hydrogen carbonate – carbonic acid Hydrogen sulfite – sulphurous acid If the anion name ends in -ite: the acid name ends with -ous acid; no hydro- prefix. eg: HNO2: NO2- is nitrite. So HNO2 is nitrous acid.

Metal Oxides Non-Metal Oxides React with water to form bases. Na2O(s) + H2O(l)  2 NaOH(aq) MgO(s) + H2O(l)  Mg(OH)2(aq) Non-Metal Oxides React with water to form acids. CO2(g) + H2O(l)  H2CO3(aq) H2co3 = carbonic acid H2so4 = sulphuric acid Last class – acids & metals, acids & carbonates  produce salts SO2(g) + H2O(l)  H2SO3(aq) Produced from burning fossil fuels When these gases go into the atmosphere they react with water to form ACID RAIN.

Assignment Homework: Workbook Pages 86, 93-94 & 92 #2