Two substances did not react with each other as expected. What is the most likely reason?

Freezing lowers the particles’ kinetic energy, so they move more slowly and collide less often and less energetically. That makes a chemical reaction less likely or slower, which could explain why the substances did not react as expected. Heating usually speeds reactions by increasing particle motion, while hitting with a hammer or placing the substances in salt solution does not necessarily prevent their reaction.

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