1. Revision of C6 Chemical synthesis

2. To provide food additives, fertilisers,, paints, pigments and pharmaceuticals. To provide food additives, fertilisers, dyestuffs, paints, pigments and pharmaceuticals. Chemical synthesis: chemical reactions and processes used to get a desired product using starting materials called reagents. The products can be useful for a variety of purposes but tend to be … fine chemicals bulk chemicals

3. Recall the formulae of …. Gases: chlorine = Cl 2, hydrogen = H 2, nitrogen= N 2, oxygen = O 2 Acids: hydrochloric acid = HCl, nitric acid = HNO 3, sulfuric acid = H 2 SO 4, Alkalis sodium hydroxide = NaOH, magnesium hydroxide Mg(OH) 2

4. Salts sodium chloride = NaCl, magnesium oxide = MgO, potassium chloride = KCl calcium chloride = CaCl 2, More complex salts… magnesium carbonate = [MgCO 3 ] magnesium sulfate = [MgSO 4 ]; sodium carbonate [Na 2 CO 3 ]; calcium carbonate [CaCO 3 ]

5. H ONLY : Work out the formulae of ionic compounds given the charges on the ions. CompoundPositive ionNegative ionFormula Sodium chloride Na + Cl - NaCl Magnesium chloride Mg 2+ Cl - MgCl 2 Calcium oxide Ca 2+ O 2- CaO Aluminium oxide Al 3+ O 2- Al 2 O 3 Magnesium sulfate Mg 2+ SO 4 2- MgSO 4

6. harmful / irritant corrosive toxic highly flammable oxidising Recall the main hazard symbols, and understand the safety precautions to use when handling hazardous chemicals.

7. Examples of pure acidic compounds which are solid, liquids and gases. Solids = citric acid & tartaric acid Liquids = sulfuric, nitric and ethanoic acids Gases = hydrogen chloride Recall common alkalis…  sodium hydroxide  potassium hydroxide  calcium hydroxide.  sodium hydroxide  potassium hydroxide  calcium hydroxide.

8. Recall the pH scale pH 1 to pH 3 shows that there is a STRONG ACID pH 4 to pH 6 shows that there is a WEAK ACID pH 7 shows that the substance is NEUTRAL pH 8 to pH 10 shows that there is a WEAK ALKALI pH 11 to pH 14 shows that there is a STRONG ALKALI

9. Metal + acid Metal + acid metal salt + hydrogen calcium + sulfuric magnesium + hydrochloric acid calcium sulfate + hydrogen magnesium chloride + hydrogen Ca(s) + H 2 SO 4 (aq)CaSO 4 (aq) + H 2 (g) Mg(s) + HCl(aq) MgCl 2 (aq) + H 2 (g)

10. Metal oxide + acid metal + acid metal salt + water copper + sulfuric magnesium + hydrochloric oxideacid oxideacid oxide copper sulfate + water magnesium chloride + water CuO(s) + H 2 SO 4 (aq) CuSO 4 (aq)+H 2 O(l) MgO(s)2HCl(aq)+MgCl 2 (aq)+H 2 O(l)

11. Metal hydroxide + acid metal + acid metal salt + water potassium + sulfuric sodium + hydrochloric hydroxide acid hydroxideacid hydroxide potassium sulfate + water sodium chloride + water 2KOH(aq) + H 2 SO 4 (aq) NaOH(aq) + HCl(aq)NaCl(aq)+ H 2 O(l) K 2 SO 4 (aq)+2H 2 O(l)

12. Metal carbonate + acid metal + acid metal salt + carbon + water copper + sulfuric magnesium +hydrochloric carbonateacid carbonateacid carbonatedioxide copper + carbon + water magnesium + carbon + water sulfatedioxide chloride CuCO 3 (s) + H 2 SO 4 (aq) CuSO 4 (aq) + CO 2 (g) + H 2 O(l) MgCO 3 (s) + 2HCl (aq)MgCl 2 (aq) + CO 2 (g) + H 2 O(l)

13. Reaction of acid with an alkali to form a salt is a neutralisation reaction. When the number of H + ions is exactly matched by the number of OH - ions to form a pH of 7 H + (aq) + OH - (aq)  H 2 O(l) An alkali can cancel out an acid to form a salt and the water (shown above) When the number of H + ions is exactly matched by the number of OH - ions to form a pH of 7 H + (aq) + OH - (aq)  H 2 O(l) An alkali can cancel out an acid to form a salt and the water (shown above) H + ions from the acid react with OH - ions from the alkali.

14. Write down the formula of the salt produced given the formula of the acid and the alkali. acidalkalisalt HClNaOHNaCl H 2 SO 4 KOHK 2 SO 4 HClCa(OH) 2 CaCl 2 H 2 SO 4 Mg(OH) 2 MgSO 4

15. C6.2 : Planning, Carrying out and controlling chemical synthesis 1. Identify the stages in the chemical synthesis of an inorganic compound. choosing the reaction or series of reactions risk assessment (chemical and procedural) working out the quantities of reactants to use carrying out the reaction in suitable apparatus in the right conditions (such as temperature, concentration or the presence of a catalyst) separating the product from the reaction mixture purifying the product measuring the yield and checking the purity of the product.

16. Understand the purpose of these techniques…. Dissolving… forming solutions to allow easy mixing of reactants Crystallisation… to purify a sample by the formation of pure crystals from a cooled (often saturated) solution, Filtration… to separate solid impurities from a solution, or to remove excess solid. Evaporation… to remove excess solvent from a solution Drying in an oven or dessicator… to remove water without the risk of wasting yield. Titration… to find the concentration of an acid (or alkali) using an alkali (or acid) of a known concentration AND an indicator

17. Balancing equations Mg(s) + 2HCl(aq)  MgCl 2 (aq) +H 2 (g) Reactants : 1 x Magnesium atom 2 x Hydrogen atoms 2 x Chlorine atoms

18. Be able to use the periodic table to obtain the relative atomic masses of elements. Look at the periodic table in your planners. The bottom number is the relative atomic mass.

19. Periodic table : Ca = 40gC = 12gO = 16g CaCO 3 = 40+12+(3x16) = 40+12+48 = 100g What is the relative formula mass of calcium carbonate? Formula of calcium carbonate = CaCO 3

20. 16g of oxygen (Relative formula mass = 32) is used to make magnesium oxide (relative formula mass = 40). How much magnesium oxide should we expect? 2Mg(s) + O 2 (g)  2MgO(s) O 8 16 On periodic table

21. Mg(s) + 2HCl(aq)  MgCl 2 (aq) +H 2 (g) 2.4g of magnesium (Relative atomic mass = 24) is used to make magnesium chloride (relative formula mass = 95). How much of this salt should we expect?

22. Calculate percentage yields given the actual and theoretical yield. actual mass of pure sample X 100 theoretical mass expected Percentage yield = So if by experiment, 7.4g of magnesium chloride was made, when theoretically 9.5g was expected; what is the percentage yield? % yield = 7.4 9.5 X 100= 0.7789 x 100= 77.8 % yield.

23. An acid-base titration is the determination of the concentration of an acid or base by exactly neutralizing the acid/base with an acid or base of known concentration. Acid-Base titrations can also be used to find percent purity of chemicals. Titrations

24. Rate of reaction If it is too fast it could make it unsafe. (eg could get too hot if exothermic; gas could be produced to quickly and pressure build up) If it is too slow, then product would be made too slowly, and yield low, so profit too low. (economic factors) Recall that reaction rates vary with…. particle size (surface area) concentration temperature.

25. Describe ways for following the rate of a reaction. 1. By collecting a gas. 2. Weighing the reaction mixture. 3. Observing colour change or precipitate.

26. Time Mass lost Chips Powder Graph shows a faster reaction with powder. Same final volume of gas made. Increasing the temperature would have the same effect.

27. Surface area The reactions of solids can clearly only take place at the surface of the solid. If we break a solid into smaller pieces we get more area and a faster reaction. Molecules collide with the surface of the solid Extra surface for molecules to collide with.

28. Reactions in solution involve dissolved particles that must collide before reaction is possible. The more crowded (concentrated) the solution, the faster the reaction because the frequency of successful collisions increases. Collisions infrequentCollisions frequent Use simple collision theory to explain how rates of reaction depend on the concentration of solutions of soluble chemicals.

29. Understand that catalysts speed up a chemical reaction while not being used up in the process. Because they are not used up, they are recyclable. For chemical reactions to occur: Existing bonds have to begin breaking so that new ones can be formed. The molecules have to collide in such a way that the reacting parts of the molecules are brought together. Catalysts can help with either or both of these processes.