what is the redox reaction between Fe2+ and MnO4 - in acid conditions used for?
a basis for a redox titration
in Fe2+ and MnO4 - reaction what happens?
Fe2+ is oxidised to Fe3+
MnO4 - is reduced to Mn2+
equation for Fe2+ and MnO4- and colour change
MnO4 - + 8H+ + 5Fe2+ —> Mn2+ + 5Fe3+ + 4H2O
purple —-> colourless
equation for Fe3+ and I- and colour change
2Fe3+ + 2I- —–> 2Fe2+ + I2
orange-brown —-> pale-green + brown
colour change is obscured by iodine’s brown colour
what happens in the reaction between Fe3+ and I-?
Fe3+ is reduced to Fe2+
I- is oxidised to I2
why is Fe2+ oxidised and MnO4 - reduced in the reaction?
electrode potential for MnO4-/Mn2+ is more positive than Fe2+/Fe3+
equation for reaction of Cr2O7 2- and Zn and colour change
Cr2O7 2- + 14H+ + 3Zn —-> 2Cr3+ + 7H2O + 3Zn2+
orange——> green
what happens if an excess of zinc is added to chromium III ions?
reduced further
Zn + 2Cr3+ —–> Zn2+ + 2Cr2+
green—–> pale blue
equation for hydrogen peroxide and chromium III
3H2O2 + 2Cr3+ + 10OH- —–> 2CrO4 2- + 8H2O
what happens in reaction for for hydrogen peroxide and chromium III?
chromium is oxidised from +3 to +6
oxygen is reduced from -1 to -2
what happens when Cu2+ reacts with excess iodide ions?
I- is oxidised to brown iodine
Cu2+ is reduced to Cu+
what does Cu+ form after after being reduced when reacting with iodide ions?
a white precipitate of copper I iodide
2Cu2+ + 4I- —> 2CuI + I2
pale blue ——> white precipitate + brown
what happens when solid copper I oxide reacts with hot dilute sulphuric acid ?
brown precipitate of copper is formed together with a blue solution of copper II sulphate
Cu + has been simultaneously oxidised and reduced so disproportionation has occurred
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25.1 introducing benzene13
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25.2 electrophilic substitution reactions of benzene18
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25.3 the chemistry in phenol17
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25.4 directing groups16
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18.1 orders, rate equations and rate constants6
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18.2 concentration-time graphs13
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18.3 rate-concentration graphs and initial rates5
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26.1 carbonyl compounds18
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26.2 identifying aldehydes and ketones7
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26.3 carboxylic acids11
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26.4 carboxylic acid derivatives31
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19.1 the equilibrium constant Kc part 24
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19.2 the equilibrium constant Kp10
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19.3 controlling the position of equilibrium12
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27.1 amines25
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20.1 brønsted-lowry acid and bases6
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20.2 pH scale and strong acids6
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20.3 the acid dissociation constant Ka13
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20.4 pH of weak acids8
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20.5 pH and strong bases6
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21.1 buffer solutions13
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21.2 buffer solutions in the body7
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21.3 neutralisation11
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22.1 lattice enthalpy10
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27.2 amino acids, amides and chirality12
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27.3 condensation polymers7
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29.1 chromatography and functional groups analysis20
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29.2 NMR spectroscopy8
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29.3 Carbon-13 NMR spectroscopy3
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22.2 enthalpy changes in solution10
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22.3 factors affecting lattice enthalpy and hydration9
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22.4 entropy13
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22.5 free energy9
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23.1 redox reactions5
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23.2 manganate (VII) redox titrations2
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23.3 iodine/thiosulfate redox titrations5
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23.4 electrode potentials22
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23.5 predictions from electrode potentials5
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23.6 storage and fuel cells14
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24.1 d-block elements16
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24.2 formation and shapes of complex ions14
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24.3 stereoisomerism in complex ions13
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24.4 ligand substitution and precipitation37
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24.5 redox and qualitative analysis13
