50.6 MB (2.8 MB compressed)
5160 x 3425 pixels
43.7 x 29.0 cm ⏐ 17.2 x 11.4 in (300dpi)
GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY GIPHOTOSTOCK / SCIENCE PHOTO LIBRARY
Calcium reacts with water, 4 of 5. Calcium metal (Ca) reacts vigorously with water (H2O), producing hydrogen gas (H2) bubbles and slightly soluble calcium hydroxide (Ca(OH)2): Ca + H2O -> Ca(OH)2 + H2. In this sequence a small chunk of calcium is dropped into a Petri dish with a shallow layer of water. The foam produced is due to H2. Formation of calcium hydroxide is accentuated by the addition of few drops of phenolphthalein indicator, which turns the solution pink, indicating alkaline solution.
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