MediumChemistryHigh School (9–10)GeneralMetals and Non-metals › Reactions and the Reactivity SeriesConceptual
Why are sodium and potassium kept under kerosene?
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Why are sodium and potassium kept under kerosene? What would happen if they were left in the open air? Why is lithium sometimes kept under oil too?
Need a reminder? The key ideaShow
Metals form basic oxides; aluminium and zinc oxides are amphoteric. Reactivity with water: K, Na violent; Ca cold water; Mg hot water; Al, Zn, Fe steam; Pb, Cu, Ag, Au none. Metals above hydrogen give hydrogen with dilute acids. A metal displaces those below it from their salt solutions.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. They react very fast with the oxygen and the moisture of the air, and can catch fire.
Step 2. In the open they would tarnish quickly, and react with water vapour to give hydrogen, which may burn.
Step 3. Lithium is in the same family and also reacts with air, though more slowly.
Answer: kerosene keeps air and water away.
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