Acids and Bases

What are Acids? Acids are common Some are dangerous and can burn your skin Some are safe to eat and drink Stomach acid helps digest food Brainstorm understanding of acids (examples, what they do, how to test) fizz dissolve dangerous, dissolve metal, burn skin Name some in kitchen Vinegar, wine gone off, citric acid, batteries What taste sour H/O what do you know abt acid and base cut n paste Read aloud H/O acid burns Zn + HCl in test tube with balloon over the top, floats can be lit (pop test) Hindenberg explosion

LecturePLUS Timberlake Acids Produce H+ (as H3O+) ions in water Produce a negative ion (-) too Taste sour Corrode metals React with bases to form salts and water LecturePLUS Timberlake

Acids Definition Examples A group of compounds which behave similarly All have low pH Turn Litmus paper RED All donate H+ ions in aqueous solution Examples Hydrochloric HCl Sulfuric H2SO4 Nitric HNO3 Ethanoic CH3COOH Demo 3 beakers add h20 pour into phenolpthaelin then base Mineral acids tend to be strong, donate lots H+ organic acids (carboxylic acids) are weak don’t fully dissociate Learn these names and formula you will be tested EXPT Fair test planning for carbonate missile

What are Bases (Alkalis)? In our home we often use bases to clean things. Eg Bleach and toothpaste Some things are not acids or bases, we say that they are neutral. Eg Water Lesson 3 Kids write from board “Acid and base are opposite one neutralises the other” Toothpaste neutralises acids formed by plaque bacteria, bee sting (formic acid baking soda neutralise) Bases which are soluble in water are called alkalis (feel soapy as they turn oils on hands into soap) EXPT make soap see H/O

Bases Definition Examples A family of compounds that behave similarly Have a high pH Turn litmus BLUE All donate OH- Examples Ammonia NH3 Sodium Hydroxide NaOH Ammonia in household cleaners NH# forms NH4+ and oh- (hydroxide ion) in water NaOH in oven cleaner, drain cleaner (dissolves grease)

LecturePLUS Timberlake Bases Produce OH- ions in water Taste bitter, chalky Are electrolytes Feel soapy, slippery React with acids to form salts and water LecturePLUS Timberlake

Measuring acid strength? To decide if something is an acid or a base we can use an indicator. Litmus and Universal Indicator are examples of indicators. They change colour depending on if they are in an acid or a base. Lesson 4 How do we test? Demo invisible writing use phenol pthaelin spray with alkali “create a colour PH scale” Indicators are extracted from plants (lichen) Ph is a measure of the conc of H+ in solution Chemicals which change colour in the presence of acids or bases EXPT universal indicator create rainbow in teams of 3 (H/O) colour ph scale naoh strong alkali, nh3 may need to dilute with water Homework bring in flower to make indicator

Working with Indicators Red litmus turns BLUE in the presence of Bases Blue litmus turns RED in the presence of acid Acids and bases react together in a NEUTRALISATION reaction Lesson 5/6 Demo frothing rainbow (KISS)?????????????????? Draw on board word equation Reactants -- Products, Acid + base --- salt + water eg HCl + NaOH - NaCl + H2O ALWAYS OBSERVE WHEN MIXING CHEMICALS SMELL< FIZZ< HEAT< COLOUR ETC EXPT H/O indicators worksheet work in groups (make own indicator) EXPT find Ph of everyday substances H/O WRITE UP CORRECTLY, conclusion BLUE ALKALI, RED ACID< GREEN NEUTRAL

LecturePLUS Timberlake Learning Check AB1 Describe the solution in each of the following as: 1) acid 2) base or 3)neutral. A. ___soda B. ___soap C. ___coffee D. ___ wine E. ___ water F. ___ grapefruit LecturePLUS Timberlake

LecturePLUS Timberlake Solution AB1 Describe each solution as: 1) acid 2) base or 3) neutral. A. _1_ soda B. _2_ soap C. _1_ coffee D. _1_ wine E. _3_ water F. _1_ grapefruit LecturePLUS Timberlake

LecturePLUS Timberlake Learning Check AB2 Identify each as characteristic of an A) acid or B) base ____ 1. Sour taste ____ 2. Produces OH- in aqueous solutions ____ 3. Chalky taste ____ 4. Is an electrolyte ____ 5. Produces H+ in aqueous solutions LecturePLUS Timberlake

LecturePLUS Timberlake Solution AB2 Identify each as a characteristic of an A) acid or B) base _A_ 1. Sour taste _B_ 2. Produces OH- in aqueous solutions _B_ 3. Chalky taste A, B 4. Is an electrolyte _A_ 5. Produces H+ in aqueous solutions LecturePLUS Timberlake

LecturePLUS Timberlake Some Common Acids HCl hydrochloric acid HNO3 nitric acid H3PO4 phosphoric acid H2SO4 sulfuric acid CH3COOH acetic acid LecturePLUS Timberlake

LecturePLUS Timberlake Some Common Bases NaOH sodium hydroxide KOH potassium hydroxide Ba(OH)2 ________________________ Mg(OH)2 ________________________ Al(OH)3 aluminum hydroxide LecturePLUS Timberlake

LecturePLUS Timberlake Learning Check AB4 Match the formulas with the names: A. ___ HNO2 1) hydrochloric acid B. ___ Ca(OH)2 2) sulfuric acid C. ___ H2SO4 3) sodium hydroxide D. ___ HCl 4) nitrous acid E. ___ NaOH 5) calcium hydroxide LecturePLUS Timberlake

LecturePLUS Timberlake Solution AB4 Match the formulas with the names: A. _4__ HNO2 1) hydrochloric acid B. _5__ Ca(OH)2 2) sulfuric acid C. _2__ H2SO4 3) sodium hydroxide D. _1__ HCl 4) nitrous acid E. _3__ NaOH 5) calcium hydroxide LecturePLUS Timberlake

LecturePLUS Timberlake Learning Check AB5 Acid, Base Name or Salt CaCl2 ______ _________________ KOH ______ _________________ Ba(OH)2 ______ _________________ HBr ______ _________________ H2SO4 ______ __________________ LecturePLUS Timberlake

LecturePLUS Timberlake Solution AB5 Acid, Base Name or Salt CaCl2 salt calcium chloride KOH base potassiuim hydroxide Ba(OH)2 base barium hydroxide HBr acid hydrobromic acid H2SO4 acid sulfuric acid LecturePLUS Timberlake

Acids A dilute acid has lots of water and a small amount of acid A concentrated acid has lots of acid and not much water so must be handled carefully A strong acid releases lots of H+ A weak acid releases fewer H+ Lesson 2 Write bomb equation NaHCo3 + CH3CooH -> Ch3CooNa +H20 + CO2 Aim to work out how to make the canister fly furthest. Can alter the amount of acid and trajectory angle. How do you ensure fair test. Discussion. Expt film canister and bicarbonate explosions who can get the furthest, FAIR TEST angle of trajectory, amount acid

Strong and Weak Acids and Bases Strong acids HCl, HNO3 , H2SO4 Most other acids are weak. Strong bases NaOH, KOH, and Ca(OH)2 Most other bases are weak. LecturePLUS Timberlake

LecturePLUS Timberlake Antacids Used to neutralize stomach acid (HCl) Many contain one or more weak bases Alka-Seltzer: NaHCO3, citric acid, and aspirin Di-gel: CaCO3 and Mg(OH)2 Gelusil: Al(OH)3 and Mg(OH)2 Maalox: Al(OH)3 and Mg(OH)2 Mylanta: Al(OH)3 and Mg(OH)2 LecturePLUS Timberlake

LecturePLUS Timberlake More Antacids Milk of Magnesia: Mg(OH)2 Rolaids: AlNa(OH)2CO3 aluminum sodium dihydroxy carbonate Tums: CaCO3 Tempo: CaCO3, Al(OH)3, Mg(OH)2 LecturePLUS Timberlake

LecturePLUS Timberlake Dilutions Add water Volume increases. New concentration is less than initial LecturePLUS Timberlake

LecturePLUS Timberlake pH Indicates the acidity [H3O+] of the solution pH = - log [H3O+] From the French pouvoir hydrogene (“hydrogen power” or power of hydrogen) LecturePLUS Timberlake

LecturePLUS Timberlake pH Range 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Neutral [H+]>[OH-] [H+] = [OH-] [OH-]>[H+] Acidic Basic LecturePLUS Timberlake

LecturePLUS Timberlake pH of Some Common Acids gastric juice 1.0 lemon juice 2.3 vinegar 2.8 orange juice 3.5 coffee 5.0 milk 6.6 LecturePLUS Timberlake

LecturePLUS Timberlake pH of Some Common Bases blood 7.4 tears 7.4 seawater 8.4 milk of magnesia 10.6 household ammonia 11.0 LecturePLUS Timberlake

Acid Rain Consider Causes Effects Chemical equations natural human Effects buildings flora fauna health Chemical equations Prevention/Solution Lesson 8/9 (show acid rain ppt? research their own) RECAP was water neutral Why not Co2 in air dissolves to form carbonic acid h2co3 DEMO Marble chips added to H2SO4 OBSERVE fizz = gas Other Minerals dissolved sulfur dioxide, from power stations volcanoes forms h2so4 and nitrogen dioxide NO2 from car exhausts ACID RAIN Acid rain H/O and reading( poss read science world pg 256) CREATE POSTER causes of acid rain, chemical reaction involved, effect on buildings, plants , fish , humans include pictures, (might want flow diagram, mind map etc) PRESENT back to class

LecturePLUS Timberlake Acid Rain Unpolluted rain has a pH of 5.6 Rain with a pH below 5.6 is “acid rain“ CO2 in the air forms carbonic acid CO2 + H2O H2CO3 Adds to H+ of rain H2CO3 H+ (aq) + HCO3-(aq) Formation of acid rain: 1. Emission of sulfur and nitrogen oxides from the burning of fuels expecially coal with high S content, power stations, oil refineries, vehicles as well as bacterial decomposition, and lighting hitting N2 SO2 26 million tons in 1980 NO and NO2 22 million tons in 1980 Mt. St Helens (1980) 400,000 tons SO2 2. Reactions in the atmosphere form SO3 2SO2 + O2  2 SO3 3. Reactions with atmosphere water form acids SO3 + H2O  H2SO4 sulfuric acid NO + H2O  HNO2 nitrous acid HNO2 + H2O  HNO3 nitric acid 4. Effects of Acid Rain Decline in fish populations in rivers and lasts due to toxic effect of Al leached from soil by acid rain Extensive fish kills in spring from runoff due to accumulation of large amounts of acid on the snow Dissolves minerals Mg, Ca, and K from the soil and waxy coatings that protect leaves from bacteria Corrodes metals, textiles, paper and leather LecturePLUS Timberlake

LecturePLUS Timberlake Sources of Acid Rain Power stations Oil refineries Coal with high S content Car and truck emissions Bacterial decomposition, and lighting hitting N2 LecturePLUS Timberlake

LecturePLUS Timberlake SO2 26 million tons in 1980 NO and NO2 22 million tons in 1980 Mt. St Helens (1980) 400,000 tons SO2 Reactions with oxygen in air form SO3 2SO2 + O2 2 SO3 Reactions with water in air form acids SO3 + H2O H2SO4 sulfuric acid NO + H2O HNO2 nitrous acid HNO2 + H2O HNO3 nitric acid LecturePLUS Timberlake

LecturePLUS Timberlake Effects of Acid Rain Leaches Al from soil, which kills fish Fish kills in spring from runoff due to accumulation of large amounts of acid in snow Dissolves waxy coatings that protect leaves from bacteria Corrodes metals, textiles, paper and leather LecturePLUS Timberlake