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READ PAGES 293 – 295 Take notes on 7.4 TEMPERATURE,QUANTITY OF HEAT AND HEAT CAPACITY

hOMeWorK. READ PAGES 293 – 295 Take notes on 7.4 TEMPERATURE,QUANTITY OF HEAT AND HEAT CAPACITY Complete questions 7,8 & 9. Check. Enthalpy of products. Enthalpy of reactants. REVIEW. What is enthalpy? What are the 2 formulas you’ve learnt for enthalpy?.

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READ PAGES 293 – 295 Take notes on 7.4 TEMPERATURE,QUANTITY OF HEAT AND HEAT CAPACITY

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  1. hOMeWorK • READ PAGES 293 – 295 • Take notes on 7.4 TEMPERATURE,QUANTITY OF HEAT AND HEAT CAPACITY • Complete questions 7,8 & 9 Check

  2. Enthalpy of products Enthalpy of reactants REVIEW • What is enthalpy? • What are the 2 formulas you’ve learnt for enthalpy? ENTHALPY is a measure of the total energy possessed by a substance or group of substances.

  3. REVIEW • What is an Endothermic Reaction? • What is an Exothermic Reaction This is a reaction that absorbs heat This is a reaction that releases heat

  4. REVIEW • What releases energy Bond Breaking / Bond Making • What needs energy Bond Breaking / Bond Making

  5. REVIEW • Which reaction is Exothermic and Enothermic? EXOTHERMIC ENDOTHERMIC

  6. The Names Bond. CHEMICAL BOND

  7. CHEMICAL BOND KJ / mol

  8. Bond breaking Energy is always required to be inputted to break a bond. Bond breaking is always endothermic.

  9. How Much Energy to Break Bonds? ** Please copy into your notes

  10. Bond making Energy is always released when a bond is formed. Bond making is always exothermic.

  11. Bond energies The energy released when a bond is formed or absorbed when it is broken is called the bond energy.

  12. Calculating ΔH for the combustion of Methane CH4(g) + 2O2(g) 2H2O(l) + CO2(g)

  13. Calculating ΔH for the combustion of Methane CH4(g) + 2O2(g) 2H2O(l) + CO2(g) H O C H H O O H H O O C H + 2 2 + Calculate the Bonds broken = __ x (C-H) + __ x (O=O) = 4 x ____ + 2 x _____ = ______ + ______ =________ KJ/mol 4 2 413 498 1662 996 2658 4 Calculate the Bonds made = __ x (O-H) + __ x (C=O) = 4 x ____ + 2 x _____ = ______ + _______ = _______ KJ/mol 2 464 805 1856 1610 3466

  14. Calculating ΔH for the combustion of Methane Calculate the Bonds broken = __ x (C-H) + __ x (O=O) = 4 x ____ + 2 x _____ = ______ + ______ =________ KJ/mol 4 2 413 498 1662 996 2658 4 Calculate the Bonds made = __ x (O-H) + __ x (C=O) = 4 x ____ + 2 x _____ = ______ + _______ = _______ KJ/mol 2 464 805 1856 1610 3466 Now that we have the break and make energy what do we do? ΔH = {energy to break bonds in reactants} – {energy to make bonds in products} ΔH = { 2658 KJ/ mol } – { 3466 KJ/ mol } ΔH = - 808 KJ / mol

  15. Now, What were you saying about not doing your worksheet?

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