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At 25 °C (77 °F), solutions of which the pH is less than 7 are acidic, and solutions of which the pH is greater than 7 are basic. Solutions with a pH of 7 at 25 °C are neutral (i.e. have the same concentration of H + ions as OH − ions, i.e. the same as pure water). The neutral value of the pH depends on the temperature and is lower than 7 ...
When a strong acid is neutralized by a strong base there are no excess hydrogen ions left in the solution. The solution is said to be neutral as it is neither acidic nor alkaline. The pH of such a solution is close to a value of 7; the exact pH value is dependent on the temperature of the solution. Neutralization is an exothermic reaction.
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 ...
The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple. [2]
In pure water, there is an equal number of hydroxide and H + ions, so it is a neutral solution. At 25 °C (77 °F), pure water has a pH of 7 and a pOH of 7 (this varies when the temperature changes: see self-ionization of water). A pH value less than 7 indicates an acidic solution, and a pH value more than 7 indicates a basic solution. [7]
A solid with enough basic strength will absorb an electrically neutral acidic indicator and cause the acidic indicator's color to change to the color of its conjugate base. [15] When performing the gaseous acid adsorption method, nitric oxide is used. [15] The basic sites are then determined by calculating the amount of carbon dioxide that is ...
In approximately neutral aqueous solution (pH ≅ 7), the basic amino group is mostly protonated and the carboxylic acid is mostly deprotonated, so that the predominant species is the zwitterion H 3 N + −RCH−COO −. The pH at which the average charge is zero is known as the molecule's isoelectric point.
An oxide is a chemical compound in which one or more oxygen atoms combined with another element, such as H 2 O or CO 2.Based on their acid-base characteristics, oxides can be classified into four categories: acidic oxides, basic oxides, and amphoteric oxides and neutral oxides.