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CHEMISTRY DEPARTMENT WAID ACADEMY

CHEMISTRY DEPARTMENT WAID ACADEMY. ENTHALPY. 25. The enthalpy of combustion of methanol, CH 3 OH, is -715 kJ mol -1 . The mass of methanol which has to be burned to produce 71.5 kJ is. 3.2 g 32g 71.5 g 715 g. 20.

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CHEMISTRY DEPARTMENT WAID ACADEMY

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  1. CHEMISTRY DEPARTMENT WAID ACADEMY ENTHALPY

  2. 25 The enthalpy of combustion of methanol, CH3OH, is -715 kJ mol-1. The mass of methanol which has to be burned to produce 71.5 kJ is • 3.2 g • 32g • 71.5 g • 715 g

  3. 20 A group of students added 6 g of ammonium chloride crystals to 200 cm3 of water at a temperature of 25oC.The enthalpy of solution of ammonium chloride is +13.6 kJ mol-1. After dissolving the crystals, the temperature of the solution would most likely be • 30oC. • 27oC. • 25oC. • 23oC.

  4. 25 Which equation illustrates an enthalpy of combustion? • A. • B. • C. • D.

  5. 20 When 3.6 g of butanal (relative formula mass = 72) was burned, 134 kJ of energy was released.From this result, what is the enthalpy of combustion, in kJ mol-1? • -6.7 • +6.7 • -2680 • +2680

  6. 20 The enthalpy of neutralisation in an acid/alkali reaction is always the energy released in • the neutralisation of one mole of acid. • the neutralisation of mole of alkali. • the formation of one mole of salt. • the formation of one mole of water.

  7. 20 A potential energy diagram for a reaction is shown below.The enthalpy change for the reaction is • -361 kJ • -227 kJ • -91kJ • +361kJ

  8. 25 Which set of data refer to the diagram shown below? • A • B • C • D Enthalpy change = - 60 kJ Activation energy = - 80 kJ Enthalpy change = +80 kJ Activation energy = - 60 kJ Enthalpy change = +60 kJ Activation energy = +80 kJ Enthalpy change = -60 kJ Activation energy = +80 kJ

  9. 20 The enthalpy change for the forward reaction shown in the diagram opposite can be represented by • x • y • x + y • x-y

  10. 20 When 0.1 g of an alcohol is burned the energy released increased the temperature of 200cm3of water from 23.1 oC to 34.2oC.Calculate the enthalpy change for this reaction in kJ mol-1. • + 4.64 kJ • - 4.64 kJ • - 9.28 kJ • + 9.28 kJ

  11. 20 When 0.01 mole of compound X is burned the energy given out raised the temperature of 250cm3 of water by 22.4oC.Calculate the enthalpy of combustion of compound X, in kJ mol-1. • - 0.936 • - 23.408 • - 234.08 • - 2340.8

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