1. C2 7.1 (a) Acids L/O * Acids produce H+ ions * Alkalis produce OH - ions * The pH scale measures the H+ ion concentration Acids in everyday life: Name of acidWhere it is foundFormula citricLemons, orangesC 6 H 7 O 7 H sulphuricCar batteryH 2 SO 4 methanoicwasp & ant stingsCHOO H hydrochloricIn the stomachH CL tannictea C 34 H 28 O 21 lacticSour milkCH 3 CH(OH)COO H ethanoicvinegarC 2 H 3 OO H Slide 1

2. Acids in food and drink: Sauces and pickles contain ethanoic acid - vinegar Vinegar preserves fruits and vegetables Fizzy drinks are made by adding carbon dioxide gas under pressure forming carbonic acid Slide 2

3. Aqueous solution: this occurs when a substance dissolves in water Dissolving Hydrogen chloride gas in water: HCl (g) H + (aq) + Cl - (aq) water All acids form H + ions when added to water. It is the hydrogen ions that make a solution acidic. Other properties of acids: * turn blue litmus red * conduct electricity ( electrolytes) * have a sour taste * have a pH less than 7 Slide 3

4. C2 7.1 (b) Bases and alkalis Bases are usually metal oxides or hydroxides and can neutralise acids. Eg CuO An alkali is a soluble base. Eg NaOH CuO MgO ZnO NaOH NH 4 OH KOH It is the OH - ion ( hydroxide ion ) which make a solution alkaline NaOH (s) Na + (aq) + OH - (aq) Sodium hydroxide solution is formed when sodium hydroxide crystals are dissolved in water NaOH NH 4 OH KOH water Other properties of alkalis turn red litmus blue conduct electricity soapy to touch have pH more than 7 Slide 4

5. C2 7.1 (c) Measuring acidity Indicators are chemicals which change colour when added to acids or alkalis. Eg. Unversal indicator - a mixture of different chemicals which change colour at different acidity strengths pH scale means ‘power of hydrogen ions present’ 0-most acidic 14-most alkaline An H+ ion is a hydrogen atom which has lost its electron. so an acid is a ‘proton donor’ Slide 5

6. Slide 6

7. C2 7.2 (a) Acids and metals L/O * acid + metal salt + hydrogen * acid + base salt + water

9. zinc hydrogen sulphatehydrogen sodiumchloridehydrogen potassium

10. C2 7.2 (b) Acids and insoluble bases Neutralisation reaction H + (aq) + OH - (aq) H 2 O (l)

11. C2 7.2 (b) Acids and insoluble bases Neutralisation reaction H + (aq) + OH - (aq) H 2 O (l)

12. Zinc Sulfate

17. Wasp stings are alkali + enzymes Dock leaves are alkali and can neutralise nettle stings (methanoic acid) neutralisation saltwater metals hydrogen bases