OmniScriptum Halochromisme : Matière, PH, Chromisme, Indicateur PH, Substance chimique, Acide, Couleur, Photochromisme, Thermochromisme

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A halochromic material is a material which changes colour when pH changes occur. The term 'chromic' is defined as materials that can change colour reversibly with the presence of a factor. In this case, the factor is pH. The pH indicators have this property. Halochromic substances are suited for use in environments where pH changes occur frequently, or places where changes in pH are extreme. Halochromic substances detect alterations in the acidity of substances, like detection of corrosion in metals. Halochromic substances may be used as indicators to determine the pH of solutions of unknown pH. The colour obtained is compared with the colour obtained when the indicator is mixed with solutions of known pH. The pH of the unknown solution can then be estimated. Obvious disadvantages of this method include its dependency on the colour sensitivity of the human eye, and that unknown solutions that are already coloured cannot be used.