1. ACIDS, BASES AND SALTS A guide for A level students 2015 SPECIFICATIONS KNOCKHARDY PUBLISHING

2. INTRODUCTION This Powerpoint show is one of several produced to help students understand selected topics at AS and A2 level Chemistry. It is based on the requirements of the AQA and OCR specifications but is suitable for other examination boards. Individual students may use the material at home for revision purposes or it may be used for classroom teaching if an interactive white board is available. Accompanying notes on this, and the full range of AS and A2 topics, are available from the KNOCKHARDY SCIENCE WEBSITE at... www.knockhardy.org.uk/sci.htm Navigation is achieved by... either clicking on the grey arrows at the foot of each page orusing the left and right arrow keys on the keyboard KNOCKHARDY PUBLISHING ACIDS, BASES AND SALTS

3. BRØNSTED-LOWRY THEORY ACIDproton donorHC l ——> H + (aq) + C l ¯ (aq) BASEproton acceptor NH 3 (aq) + H + (aq) ——> NH 4 + (aq) ACIDS AND BASES

4. ACIDSproton donorsrelease H + ions (protons) in aqueous solution STRONG ACIDS HydrochloricHC l —> H + (aq) + C l ¯ (aq) 1 replaceable H MONOPROTIC Nitric HNO 3 —> H + (aq) + NO 3 ¯ (aq) 1 replaceable H MONOPROTIC SulphuricH 2 SO 4 —> 2H + (aq) + SO 4 2- (aq) 2 replaceable H’s DIPROTIC ACIDS

5. ACIDSproton donorsrelease H + ions (protons) in aqueous solution STRONG ACIDS HydrochloricHC l —> H + (aq) + C l ¯ (aq) 1 replaceable H MONOPROTIC Nitric HNO 3 —> H + (aq) + NO 3 ¯ (aq) 1 replaceable H MONOPROTIC SulphuricH 2 SO 4 —> 2H + (aq) + SO 4 2- (aq) 2 replaceable H’s DIPROTIC WEAK ACIDS Ethanoic CH 3 COOH (aq) CH 3 COO¯ (aq) + H + (aq) MONOPROTIC ACIDS

6. BASESproton acceptors react with acids by accepting H + ions to form salts e.g.carbonatesK 2 CO 3 MgCO 3 CuCO 3 hydrogencarbonatesNaHCO 3 metal oxidesMgOZnOCuO metal hydroxidesNaOHKOHCa(OH) 2 ammoniaNH 3 BASES AND ALKALIS

7. BASESproton acceptors react with acids by accepting H + ions to form salts e.g.carbonatesK 2 CO 3 MgCO 3 CuCO 3 hydrogencarbonatesNaHCO 3 metal oxidesMgOZnOCuO metal hydroxidesNaOHKOHCa(OH) 2 ammoniaNH 3 ALKALIS SOLUBLE BASES which release OH¯ (hydroxide ions) in aqueous solution e..g.Soluble metal oxides sodium oxideNa 2 O + H 2 O (l) ——> 2Na + (aq) + 2OH¯ (aq) Soluble metal hydroxides sodium hydroxideNaOH ——> Na + (aq) + OH¯ (aq) potassium hydroxide KOH ——> K + (aq) + OH¯ (aq) Aqueous ammonia NH 3 (aq) + H 2 O (l) NH 4 + (aq) + OH¯ (aq) or NH 3 (aq) + H + (aq) NH 4 + ( aq ) BASES AND ALKALIS

8. SALTSFormed from the reaction between acids and bases hydrochloric acidmakesCHLORIDES nitric acidmakesNITRATES sulphuric acidmakesSULPHATES / HYDROGENSULPHATES SALT FORMATIONA salt is produced when the H + ion of an acid is replaced by... a metal ion or the ammonium ion NH 4 + SALTS

9. SALTSFormed from the reaction between acids and bases hydrochloric acidmakesCHLORIDES nitric acidmakesNITRATES sulphuric acidmakesSULPHATES / HYDROGENSULPHATES SALT FORMATIONA salt is produced when the H + ion of an acid is replaced by... a metal ion or the ammonium ion NH 4 + SUMMARY Acids react with... metals to givea salt + hydrogen oxides of metalsa salt + water hydroxides of metalsa salt + water carbonatesa salt + water + carbon dioxide hydrogencarbonatesa salt + water + carbon dioxide ammoniaan ammonium salt SALTS

10. Water of crystallisation loosely bonded water molecules attached to salts CuSO 4.5H 2 O FeSO 4.7H 2 O Na 2 CO 3.10H 2 O the water can be driven off by heating e.g. CuSO 4.5H 2 O (s) ———> CuSO 4 (s) + 5H 2 O (l) WATER OF CRYSTALLISATION

11. Water of crystallisation loosely bonded water molecules attached to salts CuSO 4.5H 2 O FeSO 4.7H 2 O Na 2 CO 3.10H 2 O the water can be driven off by heating e.g. CuSO 4.5H 2 O (s) ———> CuSO 4 (s) + 5H 2 O (l) HYDRATED copper(II) sulphate ANHYDROUS copper(II) sulphate BLUE CRYSTALSWHITE POWDER WATER OF CRYSTALLISATION

12. Is a typical acid in dilute aqueous solution HC l ——> H + (aq) + C l ¯(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.

13. Is a typical acid in dilute aqueous solution HC l ——> H + (aq) + C l ¯(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.

14. 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.

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

16. 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 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. SUMMARY

17. Metalsmagnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen Mg(s) + 2HC l (aq)——> MgC l 2 (aq) + H 2 (g) REACTIONS OF HYDROCHLORIC ACID 1. 1.WRITE OUT THE BALANCED EQUATION FOR THE REACTION

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

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

20. Metalsmagnesium + dil. hydrochloric acid ——> magnesium chloride + hydrogen Mg(s) + 2HC l (aq)——> MgC l 2 (aq) + H 2 (g) Mg(s) + 2H + (aq) + 2C l ¯(aq) ——> Mg 2+ (aq) + 2C l ¯(aq) + H 2 (g) cancel ions Mg(s) + 2H + (aq) ——> Mg 2+ (aq) + H 2 (g) Basic Oxidescopper(II) oxide + dil. hydrochloric acid ——> copper(II) chloride + water CuO(s) + 2HC l (aq) ——> CuC l 2 (aq) + H 2 O(l) Cu 2+ O 2- (s) + 2H + (aq) + 2C l ¯(aq) ——> Cu 2+ (aq) + 2C l ¯(aq) + H 2 O(l) cancel ions O 2- + 2H + (aq) ——> H 2 O(l) REACTIONS OF HYDROCHLORIC ACID

21. Alkalissodium hydroxide + dil. hydrochloric acid ——> sodium chloride + water NaOH(aq) + HC l (aq) ——> NaC l (aq) + H 2 O(l) Na + (aq) + OH¯(aq) + H + (aq) + C l ¯(aq) ——> Na + (aq) + C l ¯(aq) + H 2 O(l) cancel ions H + (aq) + OH¯(aq) ——> H 2 O(l) REACTIONS OF HYDROCHLORIC ACID

22. Alkalissodium hydroxide + dil. hydrochloric acid ——> sodium chloride + water NaOH(aq) + HC l (aq) ——> NaC l (aq) + H 2 O(l) Na + (aq) + OH¯(aq) + H + (aq) + C l ¯(aq) ——> Na + (aq) + C l ¯(aq) + H 2 O(l) cancel ions H + (aq) + OH¯(aq) ——> H 2 O(l) Carbonates calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water CaCO 3 (s) + 2HC l (aq) ——> CaC l 2 (aq) + CO 2 (g) + H 2 O(l) Ca 2+ CO 3 2- (s) + 2H + (aq) + 2C l ¯(aq) ——> Ca 2+ (aq) + 2C l ¯(aq) + CO 2 (g) + H 2 O(l) cancel ions CO 3 2- + 2H + (aq) ——> CO 2 (g) + H 2 O(l) REACTIONS OF HYDROCHLORIC ACID

23. Alkalissodium hydroxide + dil. hydrochloric acid ——> sodium chloride + water NaOH(aq) + HC l (aq) ——> NaC l (aq) + H 2 O(l) Na + (aq) + OH¯(aq) + H + (aq) + C l ¯(aq) ——> Na + (aq) + C l ¯(aq) + H 2 O(l) cancel ions H + (aq) + OH¯(aq) ——> H 2 O(l) Carbonates calcium carbonate + hydrochloric acid ——> calcium chloride + carbon dioxide + water CaCO 3 (s) + 2HC l (aq) ——> CaC l 2 (aq) + CO 2 (g) + H 2 O(l) Ca 2+ CO 3 2- (s) + 2H + (aq) + 2C l ¯(aq) ——> Ca 2+ (aq) + 2C l ¯(aq) + CO 2 (g) + H 2 O(l) cancel ions CO 3 2- + 2H + (aq) ——> CO 2 (g) + H 2 O(l) Hydrogen carbonates H + (aq) + HCO 3 ¯ ——> CO 2 (g) + H 2 O(l) REACTIONS OF HYDROCHLORIC ACID

24. 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

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