2 S2O32-(aq) + I2(aq) S4O62-(aq) + 2I-(aq)



I don’t claim for this list to be comprehensive, but it should prove useful. I will update this document from time to time. It may be a good idea to edit / rearrange this document (or even add to this document) to help your own needs.

Essential equations:

2 S2O32-(aq) + I2(aq) ( S4O62-(aq) + 2 I-(aq)

2 Cu2+(aq) + 4 I-(aq) ( 2 CuI(s) + I2(aq)

Cr2O72-(aq) + 14 H+(aq) + 6e- ( 2 Cr3+(aq) + 7 H2O(l)

MnO4-(aq) + 8 H+(aq) + 5e- ( Mn2+(aq) + 4 H2O(l)

Cl2(aq) +H2O ( HCl(aq) + HClO(aq).

As an ionic equation = Cl2(aq) +H2O ( Cl-(aq) + ClO-(aq) + 2H+(aq)

Cl2 + 2 NaOH(aq) ( NaCl(aq) + NaClO(aq) + H2O (happens at 20oC in dilute NaOH)

As an ionic equation = Cl2 + 2 OH-(aq) ( Cl-(aq) + ClO-(aq) + H2O(l)

3 Cl2(aq) + 6 NaOH(aq) ( 5 NaCl(aq) + NaClO3(aq) + 3 H2O(l)

As an ionic equation = 3 Cl2(aq) + 6 OH-(aq) ( 5 Cl-(aq) + ClO3-(aq) + 3 H2O(l)

3 NaClO(aq) ( 2 NaCl + NaClO3

As an ionic equation = 3 ClO-(aq) ( 2 Cl-(aq) + ClO3-(aq)

Ostwald process of nitric acid manufacture (nt there are one or two variations in doing this):

4NH3(g) + 5O2(g) 4NO(g) + 6H2O(l) – Hot 850oC. 1-2 atm. Catalyst: Pt/Rh. Oxidation

4NO(g) + 2O2(g) ( 4NO2(g) – cooler. Further oxidation!

4NO2(g) O2(g) + H2O)l) ( 4HNO3(aq) – usually concentrated to 60%. Yet more oxidation!!

Reaction of c.H2SO4 with metal halides (MX) to form hydrogen halides (HX):

i.e. NaCl, reaction of c.H2SO4 and reaction of with NaBr (forming HBr which reacts further with HBr).

Cl: c.H2SO4 + NaCl ( HCl(g) + NaHSO4(s) ( reaction stops. Not a redox reaction! H2SO4 is a stronger acid than HCl. This acid/base reaction is different in that there is no H+ FREE ions or H3O+ ions present.

Br: c.H2SO4 + NaBr ( HBr(g) + NaHSO4(s) - Not a redox reaction yet!

HBr, a hydrogen halide, reacts with remaining c.H2SO4 as follows…

HBr+ c.H2SO4 ( Br2(l) + 2H2O(l) + SO2(g) – Now the Br in HBr has been oxidized and demonstrates HBr exhibits the properties of being able to reduce S in c.H2SO4 .

The S in c.H2SO4 has been reduced and demonstrates the S in c.H2SO4 can oxidize Br in HBr.

HBr is a stronger reducing agent than HCl.

I: NaI reacts with c.H2SO4 also, forming a HI along the way. On reaction of HI with more c.H2SO4, SS and H2S are also formed, demonstrating by virtue of the fact S ends up in compounds with a lower more reduced oxidation state than happened for NaCl or NaBr, that HI is an even stronger reducing agent than HCl or HBr.

You are not expected to be able to recall (i.e. reproduce from memory) the reaction equations for the HI with c.H2SO4

s-block equations: Remember to look up the reactions of the basic oxides with HCl.

Other useful equations:

IO3-(aq) + 5I-(aq) +6H+(aq) ( 3I2(aq) + 3H2O(l) – IO3- is the iodate(V) ion. BrO3- is similar.

H2O2(aq) ( 2 H2O(aq) + O2 – Students often make a mistake when H2O2 is used in redox reactions. In this case H2O2 is undergoing disproportionation.

Decomposition of s-block carbonates and nitrates. Students sometimes make a mistake in balancing the gp2 nitrate decomposition equations.

Acid/base behavior of Al2O3 and Al(OH)3 and application to the production of Aluminium metal.

Acid base behavior of various simple Pb and Sn compounds.

Reaction of SO2 and SO3 with water.

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Normal oxides O2- + water (

Peroxides O22- + water (

Superoxides O2- + water (

aq. hydroxide

aq. hydroxide + H2O2

aq. hydroxide + H2O2 + oxygen gas

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