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28.7 x 43.2 cm ⏐ 11.3 x 17.0 in (300dpi)
GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY
Phenolphthalein indicator. Phenolphthalein indicator solution added to two test tubes containing sodium hydroxide solutions with different pH values, pH = 9 (left) and pH = 11 (right). Phenolphthalein changes its colour depending on the pH of the solution. In acidic solutions it is colourless while in basic solutions it turns into a pinkish violet (fuchsia) colour.
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