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Additional Chemistry

Additional Chemistry. The stuff you need to know. FACT: Knowing how to use your periodic table is like walking into the exam with 30% of the answers. As long as you know the differences between the particles in an atom the PT can tell you how many each contains.

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Additional Chemistry

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  1. Additional Chemistry The stuff you need to know.

  2. FACT: Knowing how to use your periodic table is like walking into the exam with 30% of the answers. • As long as you know the differences between the particles in an atom the PT can tell you how many each contains. • Atomic Mass = Protons + neutrons. • Atomic number = Protons (electrons) ATOMIC MASS C 12.0 6 ATOMIC NUMBER

  3. Complete the table!

  4. GROUPS 1 8 2 3 4 5 6 7 1 2 3 4 Non metals PERIODS Metals MAKING BONDING EASIER: Knowing the periodic table will help you first work out what bonding is taking place (ionic, covalent or metallic). It will also help you to get the atomic structure of each atom right. GROUP NUMBER = The number of electron on the outer shell PERIOD NUMBER = The number of shells

  5. A Review of Bonding. (Remember it’s all about getting a full outer shell)

  6. Draw the structures of each atom and then show the bonding that would occur. • Magnesium and Chlorine to form Magnesium Chloride. • Nitrogen and Hydrogen to form Ammonia.

  7. Relative molecular masses and moles. • As each atom has a mass so does a molecule made from different atoms. This is MOLECULAR MASS (The mass of a molecule). • We can work out molecular mass by simply adding together the masses of the atoms that make a molecule • What are the masses of the following? • H2SO4 • CaCO3 • Mg(OH)2 The reason we call the masses of atoms and molecules relative masses is because they are relative to each other (we don’t need to compare them to anything else) We make use of this when using MOLES

  8. Atom Economy Atom economy is a measure of the amount of useful stuff we get from a reaction. CaCO3(s) → CaO(s) + CO2(g) To find the atom economy we divide the relative mass of useful stuff by the relative mass of everything used and times by 100 The useful stuff from this reaction is CaO Mr of useful products Atom economy = × 100 Mr of all reactants

  9. MOLES • We use MOLES to work out how much stuff will be either needed, or made during a chemical reaction. • A MOLE OF ANY ATOM OR MOLECULE IS EQUAL TO ITS ATOMIC MASS OR MOLECULAR MASS IN GRAMS. • 1 MOLE OF ANY SUBSTANCE WILL ALWAYS CONTAIN THE SAME NUMBER OF PARTICLES (6.023 × 1023)

  10. Work out the number of moles in the following: 80g of Copper sulphate (CuSO4) 5.75g of Sodium metal (Na)

  11. Balancing equations Fe2O3(s) + CO(g) → Fe(s) + CO2(g) Make a list of the number of atoms on each side. Fe × 2 O × 4 C × 1 Try to find the easiest one to balance first Fe × 1 O × 2 C × 1 Fe2O3(s) + CO(g) → 2Fe(s) + CO2(g) Keep working at it changing the numbers as you go and eventually you will crack it Sometimes you can’t balance one thing without changing another Fe × 2 O × 4 C × 1 Fe × 2 O × 2 C × 1 Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) (s) = solid (l) = liquid (g) = gas (aq) = Solution

  12. Rates of Reaction ‘For a reaction to occur particles must collide with sufficient energy to overcome the activation energy of the reaction.’

  13. Electrolysis.Splitting compounds using electricity. Negative electrode (Cathode) Positive ions will be attracted to the cathode where they will gain electrons and become reduced Eg: Cu2+(aq) + 2e- → Cu(s) Positive electrode (Anode) Negative ions are attracted to the anode where they give up their electrons and become oxidised Eg: 2Cl-(aq) → Cl2(g)+ 2e- • You need to know how electrolysis is used in: • The production of Aluminium • The purification of Copper • Production of Hydrogen, Chlorine and Sodium Hydroxide from Brine

  14. Equilibrium: The Haber Process. N2(g) + 3H2(g) ↔ 2NH3(g) -92kJmol-1 They will eventually reach a state of dynamic equilibrium where the products are turning back into reactants as fast as they are produced In Reversible reactions products are able to turn back into reactants If you change the conditions of an equilibrium it will try to change them back! Increase the temperature and it will try to lower it by using the endothermic reaction and visa versa. Increase the pressure and it will make less molecules in order to decrease the pressure again and visa versa. If you add more of anything in the equilibrium it will move the other way to get rid of it and visa versa.

  15. Acids and Bases. • Acids are substances that donate Hydrogen ions (H+) • Acids can be both strong and weak. • H2SO4 → 2H+ + SO42- • Bases are solids or liquids that neutralise acids • They are able to accept Hydrogen ions (H+) • They can be Metal Hydroxide or Metal Oxides • HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) • CuO(s) + 2HCl(aq) → CuCl2(aq) + H2O(l) Salts are produced in neutralisation reactions, most are

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