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The above chemical equation shows the reaction between nitric acid (HNO3), a strong acid, and cobalt (Co), a metal, to produce cobalt nitrate (Co(NO3)2), water (H2O), and nitrogen monoxide (NO). This is an oxidation-reduction reaction, in which cobalt is oxidized from an oxidation state of 0 to +2, while the nitrogen in HNO3 is reduced from an oxidation state of +5 to +2.
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Reaction conditions:
- Contact between HNO3 and Co is required.
- The temperature must be sufficiently high (usually at room temperature or higher) to increase the reaction rate.
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Reaction process:
- Initially, cobalt and nitric acid react with each other to form cobalt nitrate, water, and nitrogen monoxide.
- The reaction process continues until one of the reactants is exhausted.
- The reaction will stop when there is not enough nitric acid to react with cobalt, or when the cobalt runs out.
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Phenomena occurring:
- When cobalt comes into contact with nitric acid, the pink solid of cobalt gradually disappears, replaced by the blue solution of cobalt nitrate.
- Nitrogen monoxide gas (NO) will escape, which can be recognized by its distinctive smell.