Question

why iron does not burn on heating but iron fillings burn vigorously when sprinkled in the flame of the burner?​

Answer 1

Iron has a strong molecular force of attraction. Hence when heated it doesn't reach to its ignition temperature and doesn't burn. But iron fillings when sprinkled in flames attain the ignition temperature ( as iron fillings are comparatively smaller particles) and gain larger surface area for the reaction.

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