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The question below has reference material. View the reference material and all the questions based on it.

Describe one piece of evidence that you have studied (or set of observations) that John Newlands may have used to support the Law of Octaves.

19 October 2011 · Carla Esterhuizen · 2 marks · 2 mins

The question below has reference material. View the reference material and all the questions based on it.

State one medical application of the effect in the questions above and explain briefly how it       works.

19 October 2011 · Leigh Kleynhans · 5 marks · 3 mins

State one medical application of the effect in the questions above and explain briefly how it       works.

19 October 2011 · Leigh Kleynhans · 5 marks · 3 mins

Replacing iron pipes that have corroded away can be very expensive. In order to prevent this, blocks of magnesium are attached by means of conducting wires to the iron pipes. This set up has been successful in preventing corrosion and extending the lifespan of the pipes. The magnesium blocks need to be replaced regularly, but this is easier than replacing the pipes themselves. The figure below shows how blocks of magnesium are connected to an iron pipeline buried in wet soil containing electrolytes.

pipe.png

 

 

 

Using your knowledge of chemistry, explain in detail how the use of magnesium blocks in

this way, prevents the corrosion of the iron pipes and extends their lifespan.

19 October 2011 · Leigh Kleynhans · 8 marks · 5 mins