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What happens if……

What happens if……. simple chemistry expanded. First year general chemistry examination papers. Recall of algorithms>90% Knowledge and Comprehension>70 % (Bennett 2007). 1. year general & inorganic chemistry 4 hours examination papers. Formula  names Balance chemical equations

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What happens if……

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  1. What happens if…… simple chemistry expanded Eurovariety in Chemistry Teaching

  2. First year general chemistry examination papers Recall of algorithms>90% Knowledge and Comprehension>70% (Bennett 2007) Eurovariety in Chemistry Teaching

  3. 1. year general & inorganic chemistry 4 hours examination papers • Formulanames • Balance chemical equations • pH, concentrations • Solubility (+complex formation) • Electrode potential, net reactions…. • Quantitative analyses to empirical formula • What happens if X + Y(xs)(don’t balance) Danish university, large classes (7.5 ECTS) Eurovariety in Chemistry Teaching

  4. A chemical reaction scheme Balancing (recall of algorithms) Cr2O72- + Cl- Cr3+ + Cl2(g) stoichiometry or Predicting (recall of principles) Be2+aq + nOH- ? possible reaction acid Eurovariety in Chemistry Teaching

  5. Balancing • Oxidation states of individual elements • recall rules • Oxidation state changes? • typically only two elements • Oxidation state change balance • Sum of charges • Charge balance • typically add H+ or OH- • How many atoms on each side • Atom balance • typically water Eurovariety in Chemistry Teaching

  6. Predicting 1 A+B→ ? • Recall types of reaction • acid-base reaction • redox-reaction • precipitation reaction • complex formation • Identify property of components • acidic or basic • oxidising or reducing • solubility • ligand or central ion Eurovariety in Chemistry Teaching

  7. Predicting 2 A+B→ ? • Predict possible type(s) of reaction • acid-base reaction • redox-reaction • precipitation reaction • complex formation • State formula of products Eurovariety in Chemistry Teaching

  8. Predicting 3 A+B→ ? In each of the following cases: which reaction type(s) • Reagent A in excess relative to reagent B • Reagent A and reagent B equivalent • Reagent B in excess relative to reagent A Eurovariety in Chemistry Teaching

  9. Predicting 4 A+B ? To what extent do reactions occur? • Balance relevant reaction scheme • Convert amounts (in g) to amounts (in mol) • Look up relevant equilibrium constants • Calculate final concentrations Speed of reaction (qualitatively) • Slow or fast • Chain reaction Eurovariety in Chemistry Teaching

  10. Someordinary chemicals(names only!) Copper (-wire) Gold (-foil) Aluminium (-foil) Iodine Sodium hydrogen sulphite Silver nitrate Calcium carbonate • Water • Nitric acid • Ammonia • Hydrochloric acid • Sodium hydroxide What happens if you mix this and that ? Eurovariety in Chemistry Teaching

  11. Qualitatively • Translate names into formula • Type of reaction : identify reagent type • properties of components • Extent of reaction • equilibrium • Speed of reaction • reactivity (kinetics) Eurovariety in Chemistry Teaching

  12. Quantitatively Amounts given (in g or % solution): • calculate initial amounts in mol • balance relevant equations • look up relevant equilibrium data • calculate final amounts of products • concentration of components in solution Eurovariety in Chemistry Teaching

  13. Nitric acid and Ammonia Different things may happen under different conditions Interactive programme (not fancy, nor corny, actually old-fashioned) Eurovariety in Chemistry Teaching

  14. The question Eurovariety in Chemistry Teaching

  15. Click on left bottle Eurovariety in Chemistry Teaching

  16. Mouse over concentration Eurovariety in Chemistry Teaching

  17. Click onconcentration Eurovariety in Chemistry Teaching

  18. Click on Yes (to the left) Eurovariety in Chemistry Teaching

  19. Unfolding the question Eurovariety in Chemistry Teaching

  20. Click on acid-base reaction Eurovariety in Chemistry Teaching

  21. Click on Help (4) Eurovariety in Chemistry Teaching

  22. Click Help (9) + 8.2 in Answer Eurovariety in Chemistry Teaching

  23. Back to reaction types Eurovariety in Chemistry Teaching

  24. Redox reaction of NH4NO3 Eurovariety in Chemistry Teaching

  25. Toulouse 21 Sept.2001 300 t fertilizer (NH4NO3) 50 m imagine what happened with 2300 t ammonium nitrate in Texas City harbour area 1947 Eurovariety in Chemistry Teaching

  26. Fertiliser - Explosive • Anfo – cheap commercial explosive • Terrorist’s favourite bomb? Eurovariety in Chemistry Teaching

  27. Nitric acid and Ammonia Different things may happen under different conditions 1 hour unfolding in class or 1 hour working with the programme in pairs Eurovariety in Chemistry Teaching

  28. Results Open-ended questions of this type are too hard in the first place • Instruction helps : • Activation of previous knowledge and skills • Demonstration of why recall of algorithm training is useful • Demonstration of predictive power of (sub-) microscopic models thinking • Appreciation of approach • Helpful approach to attack problem • A new way of thinking and learning Eurovariety in Chemistry Teaching

  29. Problem solving sessions to get problems solved or to learn something by solving problems Eurovariety in Chemistry Teaching

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