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19 Cards in this Set
- Front
- Back
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Standard enthalpy of combustion |
The enthalpy change, under standard conditions when one mole of a substance is completely combusted in oxygen, with all reactants and products in their standard states. |
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Standard conditions |
100 kPa and 298 K |
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Standard enthalpy of formation |
The enthalpy change under standard conditions when one mole of a compound is formed from its elements with all reactants and products in their standard state. |
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Calorimetry |
q = m c ^T ^H = -q / moles q = the heat energy change |
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Enthalpy change |
^H = E ^Hf products - E ^Hf reactants ^H = E ^Hc reactants - E ^Hf products |
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Mean bond enthalpy |
...is the average of several values of the bond taken from a range of different compounds. |
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Enthalpy change equation |
^H = E mean bond enthalpy reactants - E mean bond enthalpy products
(Bonds broken - bonds formed) |
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Rate of reaction |
Change in concentration of a substance in unit time |
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Factors effecting rate of reaction |
Concentration, surface area, temperature and a catalyst. Concentration of the reactant naturally declines as it is used up, meaning rate of reaction declines. |
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Activation energy |
Is the minimum energy required for a reaction to occur |
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Catalyst |
A substance which alters the rate of reaction without being consumed itself, by providing an alternative reaction pathway with a lower activation energy |
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Le Chatelier's principle |
A system in equilibrium will respond to oppose any change imposed upon it. |
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Factors effecting equilibrium |
Concentration, pressure, temperature and a catalyst. |
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Oxidation and oxidising agents |
Oxidation is the process of electron loss. Oxidising agents are electron acceptors (electrophiles). |
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Reduction and reducing agents |
Reduction is the gain of electrons. Reducing agents are electron donors (nucleophiles) |
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Halogen trends; electronegativity, boiling point, oxidising power |
Electronegativity decreases due to increasing atomic radius and more filled energy shells meaning the outer electron is less likely to be able to withdraw electron density from a covalent bond. Boiling point increases due to stronger van der waals between the larger molecules. Oxidising power decreases. |
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Displacement recations |
Chlorine displaces bromide and iodide. Bromine displaces iodide. Iodine shows no change. You can tell which has been displaced by the colour of the solution: chlorine: pale green, bromine: yellow,brown, iodine: brown. |
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Halide reducing agents |
Power of reducing agents increases, shown by their reaction with sulphuric acid. NaF: no redox but will produce HF NaCl: no redox but will produce HCl NaBr: produces HBr, SO2 and Br2 NaI: produces HI, SO2, H2S, S and I2 |
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Identification of halides |
Acidified silver nitrate then dilute ammonia then concentrated ammonia. F- no change as silver fluoride is soluble Cl- white precipitate, soluble in dilute Br- cream precipitate, soluble in concentrated I- yellow precipitate, insoluble |
