The ferrous iron contained in the solution is easily oxidized to trivalent iron, which reacts with tannic acid in tea to produce dark iron tannic acid.

Citric acid has reducibility, which can reduce trivalent iron to divalent iron, thus making the color of tea lighter. Adding alkaline water to tea leaves will darken the color of tea leaves. Then add citric acid to the tea, and the color of the tea will change from dark to light. Material preparation:

Alkali 10g, citric acid 10g, tea bag 1 bag, 3 glasses, dropper 1 piece.

Experimental steps:

Put the tea bag in a glass and soak half a cup of tea in warm water. Observe the color of tea at this time;

Prepare two small cups of alkaline water and citric acid solution respectively, and fully stir and dissolve them;

3. Drop the alkaline water into the tea and observe the color change of the tea;

4. Then drop the citric acid solution into the tea and observe the change of the solution;

Through the above experiments, we found that adding alkaline water to tea leaves will darken the color of tea leaves. Then add citric acid to the tea, and the color of the tea will change from dark to light.

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Experimental principle:

The ferrous iron contained in the solution is easily oxidized to trivalent iron, which reacts with tannic acid in tea to produce dark iron tannic acid. Citric acid has reducibility, which can reduce trivalent iron to divalent iron, thus making the color of tea lighter.