explain why pure dried benzoic acid does not affect litmus paper
The dry benzoic acid does not have separate benzoate and hydrogen ion. The water is necessary to allow the dry acid to dissolve and form the H3O^+ and benzoate ion.
C6H5COOH + H2O ==> H3O^+ + C6H5COO^-
Pure dried benzoic acid does not affect litmus paper because it is a weak acid and does not possess strong acidic properties. To understand why this is the case, we need to delve into the concept of acids and bases.
Litmus paper is a common indicator used to determine whether a substance is acidic or basic. It contains a pigment that changes color depending on the pH of the solution it comes into contact with. When litmus paper is dipped into an acid, it turns red, whereas when it comes into contact with a base, it turns blue.
Benzoic acid is a weak acid, meaning it only partially dissociates in water, releasing a small number of hydrogen ions (H+). The amount of hydrogen ions released by benzoic acid is not sufficient to cause a noticeable change in the pH of the solution.
On the other hand, strong acids like hydrochloric acid (HCl) or sulfuric acid (H2SO4) completely dissociate in water, yielding a large number of hydrogen ions. The high concentration of hydrogen ions from these strong acids turns the litmus paper red due to the acidic pH.
In summary, pure dried benzoic acid does not affect litmus paper because it is a weak acid and does not release enough hydrogen ions to change the pH of the solution and cause a noticeable color change in the litmus paper.