Домашние эксперименты по изменению цвета при изменении pH с антоцианом, извлеченным из черных бобов. В первом стакане находится экстрагированное вещество, во втором - отбеливатель (гипохлорит или т.п.), в третьем - обезжиривающее средство (щелочь), а в четвертом - уксус.

"гранат является фруктом; схожесть названия "гранат" с называнием соответствующего оружия является случайной и не может быть расценена как пропаганда терроризма"

(по аналогии со словесными кривляньями, практикуемыми в одной "далекой и не очень солнечной стране" по поводу статуса "иностранный агент"). Или привести армейскую шутку:

"Ты не бойся гранаты - она ручная!"

(шутки-шутками, а часть людей боится бросать боевые гранаты - инстинкт самосохранения у них развит сильнее, чем у остальных). Но вместо этого стал вспоминать.

From left to right, red cabbage juice is mixed with: vinegar, water and baking soda. The juice's original color is the central one, under acidic conditions it becomes magenta and under basic conditions it becomes green.

Слева направо сок краснокочанной капусты смешивают с уксусом, водой и пищевой содой. Первоначальный цвет сока - центральный стакан, в кислой среде он становится пурпурным, а в щелочной - зеленым.

Red Cabbage has carotenoids, a group of pigments that change according to the pH in the medium. A simple home-made indicator.

Many parts of various plants (flowers, fruits, stems, leaves, roots etc.) are painted in different colours. They contain pigments, many of which are acid-base indicators. Those pigments are able to change colour depending on the pH of the medium. Among plant pigments, the colour of which is sensitive to acids and bases, one should first of all name - anthocyanins (anthocyans), these substances belong to a wider group of flavonoids.

Such plants (or its parts) can be used for demonstration chemical experiments. E.g., many flowers are changed their colour during treatment by ammonia, hydrochloric acid, vinegar, washing soda etc.

But the same processes take place into living plants also. The same pigment(s) in the same plant can have different colour due to change of pH (in living tissue). Examples of such plants are Pulmonaria mollis and Hydrangea.

Pulmonaria mollis can have flowers of the different colours in the same plant (red, blue and purple colour). In gaseous ammonia its flower become blue and in atmosphere of hydrogen chloride the flowers of Pulmonaria mollis become red.

Flowers of Lamium purpureum (red dead-nettle) were put in the atmosphere of ammonia as well as in the atmosphere of hydrogen chloride. The purple flowers became blue then grey-green in ammonia and red in vapours of hydrochloric acid. The colour change in different parts of the petals was not the same.

Purple lilac flowers (syringa) were placed in an atmosphere of ammonia. At first the flowers had changed their colour from purple to blue-grey, then they turned grey and finally the flowers turned light brown.

Others purple lilac flowers were placed in an atmosphere of hydrogen chloride (hydrochloric acid vapours). The flowers changed colour from purple to red, while the tissues of the flowers began to be destroyed by hydrochloric acid.