CAIE A Level Chemistry 9701 · Nitrogen and sulfur
In the manufacture of certain reactive metals, a stream of nitrogen gas is used to blanket the molten metal and exclude oxygen. A student suggests that nitrogen is chosen because it is completely unreactive. Using your knowledge of the nitrogen molecule and the chemistry of nitrogen oxides, describe and explain why nitrogen is a suitable blanketing gas, and state one limitation of this choice.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Describe means: Say what happens or what something is like, in order and with detail. You are not being asked why. If there is data, quote it: name the trend, then give figures with units at the points where it changes.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.