Question

I saw this question in a GCSE past paper:

After this reaction, there is a mixture of the solids magnesium, titanium and magnesium chloride. Titanium does not react with dilute hydrochloric acid. Suggest a simple method to separate titanium from the mixture.
And in the mark scheme, one of the ways you could get the full 2 marks was with this answer:
filter the mixture (to remove titanium) / filter off the titanium (1) wash the titanium (1)
I was wondering how this would separate the titanium from the magnesium (the other way to get 2 marks was to use HCl to react with the magnesium before filtering)?

Answer 1

Titanium can be separated from magnesium and magnesium chloride by filtering the mixture to remove solid titanium and then washing it to purge any clinging impurities. An alternative method would involve using HCl to react with magnesium, forming soluble magnesium chloride, leaving titanium behind.

Step-by-step explanation:

A student saw a question on a GCSE past paper about separating titanium from a mixture that includes magnesium and magnesium chloride. To do this without making any chemicals react, one would filter the mixture which would contain solid titanium and remove it from magnesium chloride, which would be dissolved. As titanium does not react with dilute hydrochloric acid, after filtering, washing the titanium would help to remove any remaining impurities, including any magnesium particles that might be clinging to the titanium.

Another method suggested in the mark scheme involved using hydrochloric acid to react with the magnesium before filtering. This would leave titanium as the remaining solid because magnesium would react with HCl to form magnesium chloride, a soluble compound that can be washed away.