Chemguide: Support for CIE A level Chemistry

This statement deals with the reactions of the elements in Period 3 with oxygen, chlorine and water. When you look at the Chemguide page from the link below, you will find more information than you actually need. Make sure you restrict yourself to what the syllabus says.

Before you go on, you should find and read the statement in your copy of the syllabus.

You will find almost all of this on the page on reactions of the period 3 elements. I have outlined anything extra that you need below.

Reactions with oxygen

Restrict yourself to the formation of Na₂O, MgO, Al₂O₃, P₄O₁₀, SO₂ and SO₃. Ignore any other oxides mentioned.

SO₃ isn't dealt with specifically on that page, because you can't make this directly by burning sulphur in oxygen. You will find a link to the formation of sulphur trioxide in the Contact Process which you can follow if you want to, but all you need to know is:

You could burn sulphur in an excess of air or oxygen, and then pass the sulphur dioxide formed together with the excess air or oxygen over a vanadium(V) oxide catalyst at about 400 - 450°C. (Platinum is often used as an alternative catalyst in the lab.)

Reactions with chlorine

This time, you should concentrate on NaCl, MgCl₂, Al₂Cl₆, SiCl₄, and PCl₅. Ignore anything else.

Beware of aluminium chloride! The structure of this changes with conditions, and if you follow the link under the reaction of aluminium with chlorine, you will find all this described.

However, the syllabus implies that CIE want the formation of the dimer, Al₂Cl₆, and so you had better give the equation for this:

Reactions with water

This time you only need the reactions of sodium and magnesium with water.

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