ACIDSACIDS AND BASES BASES ACIDS BASES

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CONTENTS The Arrhenius Theory of acids and bases Brønsted-Lowry theory of acids and bases LEWIS THEORY – this is A2 Strong acids and bases Weak acids Weak bases Hydrogen ion concentration and pH Acid & Bases 3

Historic acid–base theories 1776 Lavoisier - he defined acids in terms of their containing oxygen 1810 Sir Humphry Davy - proved the lack of oxygen - "acidity does not depend upon any particular elementary substance, but upon peculiar arrangement of various substances". Berzelius - stated “acids are oxides of nonmetals while bases are oxides of metals” Justus von Liebig – “an acid is a hydrogen-containing substance in which the hydrogen could be replaced by a metal” 1884 Svante Arrhenius with Friedrich Wilhelm Ostwald established the presence of ions in aqueous solution Arrhenius - Nobel Prize in Chemistry in 1903 for "recognition of the extraordinary services... rendered to the advancement of chemistry by his electrolytic theory of dissociation". 4

THEORIES OF ACIDS AND BASES The Arrhenius Theory of acids and bases Acids are substances which produce hydrogen ions in solution. Bases are substances which produce hydroxide ions in solution. Neutralisation happens because hydrogen ions and hydroxide ions react to produce water. hydrogen ions + hydroxide ions  Water H + (aq) + OH¯ (aq)  H 2 O (l) 5

Limitations of the theory Hydrogen Chloride / Hydrochloric acid is neutralised by both sodium hydroxide solution and ammonia and a solution of ammonia. Word/symbol equations sodium hydroxide + hydrochloric acid  ammonia + hydrochloric acid  Ammonia dissolves in water g (g) NH 4 Cl(s) 6 HCl (aq) + NH 4 OH (aq)  NH 4 Cl (aq) + H 2 O (l)

The Bronsted-Lowry Theory of acids and bases An acid is a proton (hydrogen ion) donor. A base is a proton (hydrogen ion) acceptor. Hydroxide ions are bases - they accept hydrogen ions from acids and form water. An acid produces hydrogen ions in solution - it reacts with the water molecules by giving a proton to them. hydrogen chloride gas dissolves in water to produce hydrochloric acid, Hydroxonium ions, H 3 O +, are produced. 7

Hydroxonium ions, H 3 O +, It is important to realise that hydrogen ions in solution, H + (aq) are hydroxonium ions. 8

The hydrogen chloride / ammonia problem If it is in solution, the ammonia accepts a proton from a hydroxonium ion If the reaction is happening in the gas state, the ammonia accepts a proton directly from the hydrogen chloride: Either way, the ammonia acts as a base by accepting a hydrogen ion from an acid. NH 3 (g) + HCl (g) ——> NH 4 + (s) + Cl - (s) NH 3 (aq) + H 3 O + (aq) ——> NH 4 + (aq) + H 2 O (aq) 9

BRØNSTED-LOWRY THEORY ACIDproton donorHCl ——> H + (aq) + Cl¯(aq) BASEproton acceptor NH 3 (aq) + H + (aq) ——> NH 4 + (aq) ACIDS AND BASES 10

BRØNSTED-LOWRY THEORY ACIDproton donorHCl ——> H + (aq) + Cl¯(aq) BASEproton acceptor NH 3 (aq) + H + (aq) ——> NH 4 + (aq) Conjugate systems Acids are related to bases ACID PROTON + BASE Bases are related to acids BASE + PROTON ACID ACIDS AND BASES 11

BRØNSTED-LOWRY THEORY ACIDproton donorHCl ——> H + (aq) + Cl¯(aq) BASEproton acceptor NH 3 (aq) + H + (aq) ——> NH 4 + (aq) Conjugate systems Acids are related to bases ACID PROTON + CONJUGATE BASE Bases are related to acids BASE + PROTON CONJUGATE ACID For an acid to behave as an acid, it must have a base present to accept a proton... HA + B BH + + A¯ acid base conjugate conjugate acid base example CH 3 COO¯ + H 2 O CH 3 COOH + OH¯ base acid acid base ACIDS AND BASES 12

LEWIS THEORY – this is A2 ACIDlone pair acceptorBF 3 H + AlCl 3 BASElone pair donorNH 3 H 2 O ACIDS AND BASES LONE PAIR DONOR LONE PAIR ACCEPTOR LONE PAIR DONOR LONE PAIR ACCEPTOR 13

STRONG ACIDS completely dissociate (split up) into ions in aqueous solution e.g. HCl ——> H + (aq) + Cl¯(aq) MONOPROTIC1 replaceable H HNO 3 ——> H + (aq) + NO 3 ¯(aq) H 2 SO 4 ——> 2H + (aq) + SO 4 2- (aq) DIPROTIC 2 replaceable H’s STRONG ACIDS AND BASES 14

STRONG ACIDS completely dissociate (split up) into ions in aqueous solution e.g. HCl ——> H + (aq) + Cl¯(aq) MONOPROTIC1 replaceable H HNO 3 ——> H + (aq) + NO 3 ¯(aq) H 2 SO 4 ——> 2H + (aq) + SO 4 2- (aq) DIPROTIC 2 replaceable H’s STRONG BASES completely dissociate into ions in aqueous solution e.g. NaOH ——> Na + (aq) + OH¯(aq) STRONG ACIDS AND BASES 15

Weak acids partially dissociate into ions in aqueous solution e.g. ethanoic acid CH 3 COOH(aq) CH 3 COO¯(aq) + H + (aq) When a weak acid dissolves in water an equilibrium is set upHA(aq) + H 2 O(l) A¯(aq) + H 3 O + (aq) The water stabilises the ions To make calculations easier the dissociation can be written... HA(aq) A¯(aq) + H + (aq) WEAK ACIDS 16

Weak acids partially dissociate into ions in aqueous solution e.g. ethanoic acid CH 3 COOH(aq) CH 3 COO¯(aq) + H + (aq) When a weak acid dissolves in water an equilibrium is set upHA(aq) + H 2 O(l) A¯(aq) + H 3 O + (aq) The water stabilises the ions To make calculations easier the dissociation can be written... HA(aq) A¯(aq) + H + (aq) The weaker the acid the less it dissociates the more the equilibrium lies to the left. WEAK ACIDS 17

Partially react with water to give ions in aqueous solution e.g. ammonia When a weak base dissolves in water an equilibrium is set up NH 3 (aq) + H 2 O (l) NH 4 + (aq) + OH¯ (aq) as in the case of acids it is more simply written NH 3 (aq) + H + (aq) NH 4 + (aq) WEAK BASES 18

Partially react with water to give ions in aqueous solution e.g. ammonia When a weak base dissolves in water an equilibrium is set up NH 3 (aq) + H 2 O (l) NH 4 + (aq) + OH¯ (aq) as in the case of acids it is more simply written NH 3 (aq) + H + (aq) NH 4 + (aq) The weaker the basethe less it dissociates the more the equilibrium lies to the left WEAK BASES 19

Hydrogen ion concentration [H + (aq) ] Introductionhydrogen ion concentration determines the acidity of a solution hydroxide ion concentration determines the alkalinity for strong acids and bases the concentration of ions is very much larger than their weaker counterparts which only partially dissociate. Strong / Weak concentrated / dilute – depends on the number of particles in a set volume – depends on ionisation 20

Hydrogen ion concentration [H + (aq) ] pHhydrogen ion concentration can be converted to pH pH = - log 10 [H + (aq)] to convert pH into hydrogen ion concentration [H + (aq)] = antilog (-pH) in both the above, [ ] represents the concentration in mol dm -3 The calculation is A2 but the understanding is AS ! STRONGLY ACIDIC pH OH¯ [H + ] WEAKLY ACIDIC NEUTRAL STRONGLY ALKALINE WEAKLY ALKALINE 21

Acids and Bases Tasks – page Key definitions an acid.. a base.. an alkali... Examiners tips are.. Worksheet Questions : 1, 2 Rainbow fizz ? 22

Is a typical acid in dilute aqueous solution HCl ——> H + (aq) + Cl¯(aq) REACTIONS OF HYDROCHLORIC ACID Hydrogen chloride is a colourless covalent gas; it is a poor conductor of electricity because there are no free electrons or ions present. It has no action on dry litmus paper because there are no aqueous hydrogen ions present. 23

Is a typical acid in dilute aqueous solution HCl ——> H + (aq) + Cl¯(aq) REACTIONS OF HYDROCHLORIC ACID Hydrogen chloride is a colourless covalent gas; it is a poor conductor of electricity because there are no free electrons or ions present. It has no action on dry litmus paper because there are no aqueous hydrogen ions present. If the gas is passed into water, the hydrogen chloride molecules dissociate into ions. The solution now conducts electricity showing ions are present. For each hydrogen chloride molecule that dissociates one hydrogen ion and one chloride ion are produced. The solution turns litmus paper red because of the H + (aq) ions. 24

Is a typical acid in dilute aqueous solution HCl ——> H + (aq) + Cl¯(aq) REACTIONS OF HYDROCHLORIC ACID Hydrogen chloride is a colourless covalent gas; it is a poor conductor of electricity because there are no free electrons or ions present. It has no action on dry litmus paper because there are no aqueous hydrogen ions present. If the gas is passed into water, the hydrogen chloride molecules dissociate into ions. The solution now conducts electricity showing ions are present. For each hydrogen chloride molecule that dissociates one hydrogen ion and one chloride ion are produced. The solution turns litmus paper red because of the H + (aq) ions. 25

Is a typical acid in dilute aqueous solution HCl ——> H + (aq) + Cl¯(aq) REACTIONS OF HYDROCHLORIC ACID HYDROGEN CHLORIDE HYDROCHLORIC ACID colourless gas Appearance colourless soln. covalent molecule Bonding aqueous ions HCl(g) Formula HCl(aq) poor Conductivity good no reaction Dry blue litmus goes red 26

Is a typical acid in dilute aqueous solution HCl ——> H + (aq) + Cl¯(aq) REACTIONS OF HYDROCHLORIC ACID Appearance Bonding and formula Conductivity Dry litmus hydrogen chloridecolourless gas covalent molecule HCl(g) poor no reaction hydrochloric acidcolourless soln. aqueous ions HCl(aq) good goes red 27

28 Practical Activities Reactive Metals and Acids Magnesium : Mg Hydrochloric Acid : HCl : 1.0 M Put 5 cm 3 of HCl in a boiling tube drop in the Mg strip Seal with hand Wait for 1 to 2 minutes – until the pressure builds up Attempt to ignite the trapped gas Record your observations The metal reactants – dissolves into the acid The metal disappears ? Acid in excess? A clear colourless solution forms A soluble compound is form – no precipitate / solid formed Effervescence occurs – a gas is produced It’s colourless, its flammable gas - squeaky pop inference – H 2 magnesium + hydrochloric acid →

Metalsmagnesium + hydrochloric acid ——> magnesium chloride + hydrogen Mg(s) + 2HCl(aq)——> MgCl 2 (aq) + H 2 (g) REACTIONS OF HYDROCHLORIC ACID 1.WRITE OUT THE BALANCED EQUATION FOR THE REACTION 29

Metalsmagnesium + hydrochloric acid ——> magnesium chloride + hydrogen Mg(s) + 2HCl(aq)——> MgCl 2 (aq) + H 2 (g) Mg(s) + 2H + (aq) + 2Cl¯(aq) ——> Mg 2+ (aq) + 2Cl¯(aq) + H 2 (g) REACTIONS OF HYDROCHLORIC ACID 1.WRITE OUT THE BALANCED EQUATION FOR THE REACTION 2.DILUTE ACIDS AND SALTS CONTAIN IONS; WATER, HYDROGEN & CARBON DIOXIDE DON’T 30

Metalsmagnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen Mg(s) + 2HCl(aq)——> MgCl 2 (aq) + H 2 (g) Mg(s) + 2H + (aq) + 2Cl¯(aq) ——> Mg 2+ (aq) + 2Cl¯(aq) + H 2 (g) cancel ions Mg(s) + 2H + (aq) ——> Mg 2+ (aq) + H 2 (g) REACTIONS OF HYDROCHLORIC ACID 1.WRITE OUT THE BALANCED EQUATION FOR THE REACTION 2.DILUTE ACIDS AND SALTS CONTAIN IONS; WATER, HYDROGEN & CARBON DIOXIDE DON’T 3.CANCEL OUT THE IONS WHICH APPEAR ON BOTH SIDES OF THE EQUATION 31

32 Practical Activities Bases and Acids Insoluble Metal Oxide : Copper Oxide Hydrochloric Acid : HCl : 1.0 M Put ½ a spatula of CuO in a boiling tube Add 5-10 cm3 HCl ( that’s about a 1/3 of a Boiling tube ) Mix by gentle agitation Wait for the reaction – warm gently if required Record your observations The metal oxide (black/grey power solid) reactants slowly It dissolves into the acid/reacts with the acid A clear ? Green/blue ? solution forms A soluble compound is form – no precipitate / solid left is ? No Effervescence occurs – no gas is produced Acid in excess ? copper(II) oxide + hydrochloric acid →

Basic Oxides Insoluble oxides copper(II) oxide + hydrochloric acid ——> copper(II) chloride + water CuO(s) + 2HCl(aq) ——> CuCl 2 (aq) + H 2 O(l) Cu 2+ O 2- (s) + 2H + (aq) + 2Cl¯(aq) ——> Cu 2+ (aq) + 2Cl¯(aq) + H 2 O(l) cancel ions O H + (aq) ——> H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 33

34 Practical Activities Metal Hydroxides and Acids soluble Metal hydroxide : sodium hydroxide : NaOH Hydrochloric Acid : HCl : 1.0 M Put 25cm 3 NaOH in insulated beaker add 2-3 drops of indicator Record initial temperature and colour of the indicator Add 1.0 HCl 2 cm 3 at a time – record the temperature Add a maximum of 40 cm HCl Record any observations- results table Plot – SKETCH your results – on graph paper Volume v ∆T ( or just T ) – add indicator colour changes Does the max temperature correlate with the indicator change ? At what volume did the maximum ∆T occur sodium hydroxide + hydrochloric acid → Volume of Acid added cm 3 Temperatur e °C Indicator Colour 0 Initial temp 2 4 until you reach 40

35 Volume of Acid added cm 3 Temperature °C Indicator Colour 0Initial temp 2 4 until you reach 40

REACTIONS OF HYDROCHLORIC ACID sodium hydroxide + hydrochloric acid ——> sodium chloride + water NaOH(aq) + HCl(aq) ——> NaCl(aq) + H 2 O(l) Na + (aq) + OH¯(aq) + H + (aq) + Cl¯(aq) ——> Na + (aq) + Cl¯(aq) + H 2 O(l) cancel ions H + (aq) + OH¯(aq) ——> H 2 O(l) 36 Alkalis

REACTIONS OF HYDROCHLORIC ACID sodium hydroxide + hydrochloric acid ——> sodium chloride + water NaOH(aq) + HCl(aq) ——> NaCl(aq) + H 2 O(l) Na + (aq) + OH¯(aq) + H + (aq) + Cl¯(aq) ——> Na + (aq) + Cl¯(aq) + H 2 O(l) cancel ions H + (aq) + OH¯(aq) ——> H 2 O(l) 37 Alkalis

38 Practical Activities Alkalis and Acids Sparing soluble Metal Hydroxide : Magnesium Hydroxide Hydrochloric Acid : HCl : 1.0 M Put one a spatula of MgO / Mg(OH) 2 in beaker/conical flask Add about 25 cm 3 of water and 2-3 drops of Universal Indicator Add HCl slowly : that’s 2-3 cm 3 at a time Mix by gentle agitation Stop when you have added about 30 cm3 Record your observations The metal oxide/hydroxide (white power solid) does not readily dissolve Alkalis solution formed Acid reacts with alkali neutralizing it but on standing reverts back to alkali. A soluble compound is form – no precipitate / solid left ? No Effervescence occurs – no gas is produced Acid in excess ?

magnesium hydroxide – add water.. Check pH magnesium hydroxide + hydrochloric acid ——> magnesium chloride + water Mg(OH) 2 (s) + 2 HCl(aq) ——> MgCl 2 (aq) + 2 H 2 O(l) Mg 2+ (aq) + 2 OH¯(aq) + 2 H + (aq) + 2 Cl¯(aq) ——> Mg 2+ (aq) + 2 Cl¯(aq) + 2 H 2 O(l) cancel ions 2 H + (aq) + 2 OH¯(aq) ——> 2 H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 39 Alkalis

40 Practical Activities Carbonates and Acids Insoluble Metal carbonates : calcium carbonate: CaCO 3 Hydrochloric Acid : HCl : 1.0 M Add 5 cm 3 HCl ( that’s less than a 1/3 of a Boiling tube ) Add universal indicator Put lumps CaCO 3 in a boiling tube Mix by gentle agitation Wait for the reaction to go to completion Test the gas with a lighted splint Record your observations The solid CaCO 3 reactants slowly Effervescence occurs – a gas is produced.. Not flammable Called CO 2 – test ? Universal indicator changes colour RED to PINK ? To... GREEN It dissolves into the acid/reacts with the acid A clear ? solution forms ? A soluble compound is form – no precipitate / solid left is ? Acid in excess ?

Carbonates – add water... Check pH calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water CaCO 3 (s) + 2HCl(aq) ——> CaCl 2 (aq) + CO 2 (g) + H 2 O(l) Ca 2+ CO 3 2- (s) + 2H + (aq) + 2Cl¯(aq) ——> Ca 2+ (aq) + 2Cl¯(aq) + CO 2 (g) + H 2 O(l) cancel ions CO H + (aq) ——> CO 2 (g) + H 2 O(l) Test for Carbon Dioxide Calcium hydroxide + carbon dioxide ——> Calcium carbonate + water Ca(OH) 2 + CO 2 (g) ——> CaCO 3 (s) + H 2 O(l) Ca 2+ (aq) + 2 OH¯(aq) + CO 2 (g) ——> Ca 2+ (s) + + CO 3 2- (s) + H 2 O(l) 2 OH¯(aq) + CO 2 (g) ——> CO 3 2- (s) + H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 41

42 Practical Activities Bubbling CO2 into water/lime water Straws Boiling tubes Phenolphthalein indicator / universal indicator Limewater Tap water Put 5 cm 3 of water in a boiling tube 2 drop of universal indicator Record your observations Put 5 cm 3 of lime water in a boiling tube 2 drop of phenolphthalein indicator Record your observations Why does the precipitate disappear ?

Carbonates – add water... Check pH calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water CaCO 3 (s) + 2HCl(aq) ——> CaCl 2 (aq) + CO 2 (g) + H 2 O(l) Ca 2+ CO 3 2- (s) + 2H + (aq) + 2Cl¯(aq) ——> Ca 2+ (aq) + 2Cl¯(aq) + CO 2 (g) + H 2 O(l) cancel ions CO H + (aq) ——> CO 2 (g) + H 2 O(l) Hydrogen carbonates – add water... Check pH Sodium hydrogen carbonate + hydrochloric acid ——> sodium chloride + carbon dioxide + water NaHCO 3 (aq) + HCl(aq) ——> NaCl(aq) + CO 2 (g) + H 2 O(l) Na + (aq) + HCO 3 ¯ (aq) + H + (aq) + Cl¯(aq) ——> Na + (aq) + Cl¯(aq) + CO 2 (g) + H 2 O(l) HCO 3 ¯ (aq) + H + (aq)——> CO 2 (g) + H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 43

What happens if you keep bubbling CO 2 into water ? carbon dioxide + water——> carbonic acid CO 2 (g) + H 2 O(l) ——> H 2 CO 3 (aq) 2 H 2 CO 3 (aq) + CaCO 3 (s) ——> Ca ( HCO 3 ) 2 (aq) + CO 2 (g) + H 2 O(l) Ca 2+ CO 3 2- (s) + 2H + (aq) + CO 3 2- (aq) ——> HCO 3 ¯ (aq) + CO 2 (g) + H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 44

45 Practical Activities ammonia and hydrochloric acid conc. NH 3 /conc. HCl 2 gas jars. Universal indicator Paper 2 -3 drops in separate gas jars – check pH Invert one jar over the other. Record observations NH 3 HCl

ammonia + hydrochloric acid ——> ammonium chloride NH 3 (g) + HCl(g) ——> NH 4 Cl(s) NH 3 (g) + HCl(g) ——> NH 4 + (s) + Cl¯(s) REACTIONS OF HYDROCHLORIC ACID 46

Ammonium hydroxide Ammonium hydroxide + hydrochloric acid ——> ammonium chloride + water NH 4 OH(aq) + HCl(aq) ——> NH 4 Cl (aq) + H 2 O(l) NH 4 + (aq) + OH¯ (aq) + H + (aq) + Cl¯(aq) ——> NH 4 + (aq) + Cl¯(aq) + H 2 O(l) cancel ions OH¯(aq) + H + (aq)——> H 2 O(l) REACTIONS OF HYDROCHLORIC ACID 47

Carbonates calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water Alkalis sodium hydroxide + hydrochloric acid ——> sodium chloride + water Hydrogen carbonates Sodium hydrogen carbonate + hydrochloric acid ——> sodium chloride + carbon dioxide + water Basic Oxides copper(II) oxide + hydrochloric acid ——> copper(II) chloride + water Metals magnesium + hydrochloric acid ——> magnesium chloride + hydrogen REACTIONS OF HYDROCHLORIC ACID ammonia ammonia + hydrochloric acid ——> ammonium salts 48

SUMMARY METALS react to givea salt + hydrogen METAL OXIDES react to givea salt + water METAL HYDROXIDES react to givea salt + water CARBONATES react to give a salt + water + carbon dioxide HYDROGENCARBONATES react to give a salt + water + carbon dioxide AMMONIA reacts to givean ammonium salt REACTIONS OF HYDROCHLORIC ACID 49

Tasks... Page Key definitions a salt.. an anion.. a cation... Examiners tips are.. Worksheet – word equations.. to symbol equations Questions : 1, 2 50

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19) ?___________________________ + sulphuric acid ===> iron(II) sulphate + hydrogen 20) zinc oxide + ?___________________________ ===> zinc chloride + water 21) copper(II) carbonate + sulphuric acid ===> ?_____________________ + water + carbon dioxide 22) aluminium + ?___________________________ ===> aluminium sulphate + hydrogen 23) calcium oxide + hydrochloric acid ===> ?______________________ + ?_________________ 24) magnesium hydroxide + ?________________ ===> magnesium sulphate + ?________________ 25) ammonia + sulphuric acid ===> ?___________________________ 26) ammonia + ?___________________________ ===> ammonium chloride 27) zinc hydroxide + sulphuric acid ===> ?_____________________ + ?______________ 28) copper(II) oxide + hydrochloric acid ===> ?___________________________ + water 29) sodium hydroxide + sulphuric acid ===> ?___________________________ + water 30) sodium hydrogencarbonate + hydrochloric acid ===> ?______________ + ?_______________ +?________________ 31) ammonia + ?___________________________ ===> ammonium nitrate 32) calcium oxide + ?_____________________ ===> calcium chloride + ?_____________________ 33) aluminium hydroxide + nitric acid ===> ?___________________________ + water 34) calcium carbonate + ?________________ ===> calcium ethanoate + ?____________ + ?________________ 35) ethanoic acid + magnesium ===> ?____________________ + hydrogen 36) _________________ + magnesium oxide ===> magnesium ethanoate + ?____________ 37) sodium hydroxide + ?_______________ ===> ?_____ ethanoate + ?_____________ 52

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Now write the full symbol equations Check the formula of the compounds Make sure you balance the equations Add the state symbols Most formulas you should know but these may help Formulas – copper II hydroxide Cu(OH) 2 lead II hydroxide Pb(OH) 2 54

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56 Practical Activities Reactive Metals and Acids Magnesium : Mg Hydrochloric Acid : HCl : 1.0 M Put 5 cm 3 of HCl in a boiling tube drop in the Mg strip Seal with hand Wait for 1 to 2 minutes – until the pressure builds up Record your observations The metal reactants – dissolves into the acid The metal disappears ? Acid in excess? A clear colourless solution forms A soluble compound is form – no precipitate / solid formed Effervescence occurs – a gas is produced It’s colourless, its flammable gas - squeaky pop inference – H 2

57 Practical Activities Bases and Acids Insoluble Metal Oxide : Copper Oxide Hydrochloric Acid : HCl : 1.0 M Put ½ a spatula of CuO in a boiling tube Add 5-10 cm3 HCl ( that’s about a 1/3 of a Boiling tube ) Mix by gentle agitation Wait for the reaction – warm gently if required Record your observations The metal oxide (black/grey power solid) reactants slowly It dissolves into the acid A clear ? Green/blue ? solution forms A soluble compound is form – no precipitate / solid left No Effervescence occurs – no gas is produced Acid in excess ?

58 Practical Activities Metal Hydroxides and Acids soluble Metal hydroxide : sodium hydroxide : NaOH Hydrochloric Acid : HCl : 1.0 M Put 25cm 3 NaOH in insulated beaker add 2-3 drops of indicator Record initial temperature Add 0.1 HCl 2 cm 3 at a time – record the temperate Add a maximum of 40 cm HCl Plot your results Volume v ∆T – add indicator colour changes Record any observations Does the max temperature correlate with the indicator change ? At what volume did the maximum ∆T occur

59 Practical Activities Alkalis and Acids Sparing soluble Metal Hydroxide : Magnesium Hydroxide Hydrochloric Acid : HCl : 1.0 M Put one a spatula of MgO / Mg(OH) 2 in beaker/conical flask Add about 25 cm 3 of water and 2-3 drops of Universal Indicator Add HCl slowly : that’s 2-3 cm 3 at a time Mix by gentle agitation Stop when you have added about 30 cm3 Record your observations The metal oxide/hydroxide (white power solid) does not readily dissolve Alkalis solution formed Acid reacts with alkali neutralizing it but on standing reverts back to alkali. A soluble compound is form – no precipitate / solid left ? No Effervescence occurs – no gas is produced Acid in excess ?

60 Practical Activities Carbonates and Acids Insoluble Metal carbonates : calcium carbonate: CaCO 3 Hydrochloric Acid : HCl : 1.0 M Add 5-10 cm 3 HCl ( that’s about a 1/3 of a Boiling tube ) Add universal indicator Put lumps CaCO 3 in a boiling tube Mix by gentle agitation Wait for the reaction to go to completion Test the gas with a lighted splint Record your observations The solid CaCO 3 reactants slowly Effervescence occurs – a gas is produced.. Not flammable Called CO 2 – test ? Universal indicator changes colour RED to PINK ? To... GREEN It dissolves into the acid/reacts with the acid A clear ? solution forms ? A soluble compound is form – no precipitate / solid left is ? Acid in excess ?

61 Practical Activities Bubbling CO2 into water/lime water Straws Boiling tubes Phenolphthalein indicator / universal indicator Limewater Tap water Put 5 cm 3 of water in a boiling tube 2 drop of universal indicator Record your observations Put 5 cm 3 of lime water in a boiling tube 2 drop of phenolphthalein indicator Record your observations Why does the precipitate disappear ?

62 Practical Activities ammonia and hydrochloric acid conc. NH 3 /conc. HCl – in bottle with glass droppers 2 Gas Jars Universal indicator Paper – wet it first ? Put 2 -3 drops of HCl/NH 3 in separate gas jars – check pH Invert one jar over the other. ( HCl on top ? ) Record observations NH 3 HCl

63 Practical Activities Reactive Metals and Acids Magnesium : Mg ribbon Hydrochloric Acid : HCl : 1.0 M boiling tube Wooden splints Bases and Acids Insoluble Metal Oxide : Copper Oxide Hydrochloric Acid : HCl : 1.0 M boiling tube Metal Hydroxides and Acids soluble Metal hydroxide : sodium hydroxide : NaOH 1.0 M Hydrochloric Acid : HCl : 1.0 M insulated beaker Thermometer 25 / 50 cm3 measuring cylinders Alkalis and Acids Magnesium Hydroxide - solid Hydrochloric Acid : HCl : 1.0 M conical flask universal indicator solution Carbonates and Acids Insoluble Metal carbonates : calcium carbonate: CaCO 3 - solid Hydrochloric Acid : HCl : 1.0 M universal indicator solution Boiling tube

64 Bubbling CO2 into water/lime water Straws Boiling tubes x 2 Phenolphthalein indicator / universal indicator Limewater ammonia and hydrochloric acid conc. NH 3 /conc. HCl – in bottle with glass droppers 2 Gas Jars Universal indicator Paper

65 ‘Name’ of AcidFormulaionName of ion Hydrochloric acidHCl Cl - chloride Carbonic acidH 2 CO 3 CO 3 - Carbonate (V) Nitric acidHNO 3 NO 3 - Nitrate (v) Nitrous acidHNO 2 NO 2 - Nitrate (III) Sulphuric acidH 2 SO 4 SO Sulphate (VI) Sulphurous acidH 2 SO 3 SO Sulphate (IV) Ethanoic acidCH 3 COOH CH 3 COO - ethanoate

66 Exercise 1 - Deduce the formulae of the following compounds: a)Sodium oxide b)Calcium hydroxide c)Ammonium nitrate d)Potassium carbonate e)Strontium sulphate f)Ammonium sulphate g)Hydrochloric acid h)Rubidium hydroxide i)Magnesium carbonate j)Calcium nitrate k)Sulphuric acid l)Ammonium chloride m)Nitric acid n)Potassium sulphate o)Magnesium oxide p)Caesium bromide q)Barium sulphate r)Strontium nitrate a)Na 2 Obase b)Ca(OH) 2 base c)NH 4 NO 3 salt d)K 2 CO 3 base e)SrSO 4 salt f)(NH 4 ) 2 SO 4 salt g)HClacid h)RbOHbase i)MgCO 3 base j)Ca(NO 3 ) 2 salt k)H 2 SO 4 acid l)NH 4 Clsalt m)HNO 3 acid n)K 2 SO 4 salt o)MgObase p)CsBrsalt q)BaSO 4 salt r)Sr(NO 3 ) 2 salt

67 a)Na 2 Obase b)Ca(OH) 2 base c)NH 4 NO 3 salt d)K 2 CO 3 base e)SrSO 4 salt f)(NH 4 ) 2 SO 4 salt g)HClacid h)RbOHbase i)MgCO 3 base j)Ca(NO 3 ) 2 salt k)H 2 SO 4 acid l)NH 4 Clsalt m)HNO 3 acid n)K 2 SO 4 salt o)MgObase p)CsBrsalt q)BaSO 4 salt r)Sr(NO 3 ) 2 salt

68 Exercise 3 – Write balanced symbol equations, with state symbols, for the following reactions: a)Nitric acid with potassium b)hydroxide solution c)Sulphuric acid with sodium hydroxide solution d)Hydrochloric acid with calcium hydroxide powder e)Nitric acid with calcium oxide powder f)Hydrochloric acid with barium oxide powder g)Sulphuric acid with magnesium oxide powder h)Nitric acid with calcium carbonate powder i)Hydrochloric acid with barium carbonate powder j)Sulphuric acid with sodium carbonate solution k)Nitric acid with ammonia solution l)Sulphuric acid with ammonia solution m)Hydrochloric acid with ammonia solution

69 a)HNO 3 (aq) + KOH(aq)  KNO 3 (aq) + H 2 O(l) b)H 2 SO 4 (aq) + 2NaOH(aq)  Na 2 SO 4 (aq) + H 2 O(l) c)2HCl(aq) + Ca(OH) 2 (s)  CaCl 2 (aq) + H 2 O(l) d)2HNO 3 (aq) + CaO(s)  Ca(NO 3 ) 2 (aq) + H 2 O(l) e)2HCl(aq) + BaO(s)  BaCl 2 (aq) + H 2 O(l) f)H 2 SO 4 (aq) + MgO(s)  MgSO 4 (aq) + H 2 O(l) g)2HNO 3 (aq) + CaCO 3 (s)  Ca(NO 3 ) 2 (aq) + CO 2 (g) + H 2 O(l) h)2HCl(aq) + BaCO 3 (s)  BaCl 2 (aq) + CO 2 (g) + H 2 O(l) i)H 2 SO 4 (aq) + Na 2 CO 3 (aq)  Na 2 SO 4 (aq) + CO 2 (g) + H 2 O(l) j)HNO 3 (aq) + NH 3 (aq)  NH 4 NO 3 (aq) k)H 2 SO 4 (aq) + 2NH 3 (aq)  (NH 4 ) 2 SO 4 (aq) l)HCl(aq) + NH 3 (aq)  NH 4 Cl(aq)

70 Titration Questions Page 37/38 Questions 5, 6, 7