Chemguide: Support for CIE A level Chemistry

Learning outcome 9.2(a)

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.)

Note:  You may possibly have noticed that I am using the spelling "sulphur" rather than "sulfur". CIE uses "sulfur", but I have decided to stick with the traditional English spelling "sulphur" in order to be consistent with the rest of Chemguide. It really doesn't matter which version you use!

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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© Jim Clark 2010 (last modified May 2104)