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2. Phenolphthalein - Wikipedia

   en.wikipedia.org/wiki/Phenolphthalein

   Phenolphthalein is used in toys, for example as a component of disappearing inks, or disappearing dye on the "Hollywood Hair" Barbie hair. In the ink, it is mixed with sodium hydroxide, which reacts with carbon dioxide in the air. This reaction leads to the pH falling below the color change threshold as hydrogen ions are released by the reaction:

3. Kastle–Meyer test - Wikipedia

   en.wikipedia.org/wiki/Kastle–Meyer_test

   In order to generate the intense pink color indicative of a positive test, the reduced phenolphthalein must be oxidized back to its normal, colored form. In the relevant reaction, hydrogen peroxide reacts with the hemoglobin in the blood. Phenolphthalein does not directly participate in this process; instead, it acts as an external source of ...

4. pH indicator - Wikipedia

   en.wikipedia.org/wiki/PH_indicator

   In and of themselves, pH indicators are usually weak acids or weak bases. The general reaction scheme of acidic pH indicators in aqueous solutions can be formulated as: HInd (aq) + H 2 O (l) ⇌ H 3 O + (aq) + Ind − (aq) where, "HInd" is the acidic form and "Ind −" is the conjugate base of the indicator. Vice versa for basic pH indicators ...

5. Universal indicator - Wikipedia

   en.wikipedia.org/wiki/Universal_indicator

   A roll of universal indicator pape Colors of universal indicator. A universal indicator is a pH indicator made of a solution of several compounds that exhibit various smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. A universal indicator can be in paper form or present in a form of a solution ...

6. Acid–base titration - Wikipedia

   en.wikipedia.org/wiki/Acid–base_titration

   An acid–base titration is a method of quantitative analysis for determining the concentration of Brønsted-Lowry acid or base (titrate) by neutralizing it using a solution of known concentration (titrant). [1] A pH indicator is used to monitor the progress of the acid–base reaction and a titration curve can be constructed. [1]

7. Neutralization (chemistry) - Wikipedia

   en.wikipedia.org/wiki/Neutralization_(chemistry)

   The reaction is consistent with the Brønsted–Lowry definition because in reality the hydrogen ion exists as the hydronium ion, so that the neutralization reaction may be written as H 3 O + + OH − → H 2 O + H 2 O. When a strong acid is neutralized by a strong base there are no excess hydrogen ions left in the solution.

8. Base (chemistry) - Wikipedia

   en.wikipedia.org/wiki/Base_(chemistry)

   A strong base is a basic chemical compound that can remove a proton (H +) from (or deprotonate) a molecule of even a very weak acid (such as water) in an acid–base reaction. Common examples of strong bases include hydroxides of alkali metals and alkaline earth metals, like NaOH and Ca(OH) 2, respectively. Due to their low solubility, some ...

9. Amphoterism - Wikipedia

   en.wikipedia.org/wiki/Amphoterism

   Related words in acid-base chemistry are amphichromatic and amphichroic, both describing substances such as acid-base indicators which give one colour on reaction with an acid and another colour on reaction with a base. [3]