Weak Acid Buffer

Few compounds act as strong acids. A far greater number of compounds behave as weak acids and only partially react with water, leaving a large majority of dissolved molecules in their original form and generating a relatively small amount of hydronium ions. Weak acids are commonly encountered in nature, being the substances partly responsible for the tangy taste of citrus fruits, the stinging sensation of insect bites, and the unpleasant smells associated with body odor. A familiar example of a...

Calculating pH for Titration Solutions: Weak Acid/Strong Base For the titration of 25.00 mL of 0.100 M CH3CO2H with 0.100 M NaOH, the reaction can be represented as: The pH of the titration solution after the addition of the different volumes of NaOH titrant can be calculated as follows: (a) The initial pH is computed for the acetic acid solution in the usual ICE approach: (b) The acid and titrant are both monoprotic and the sample and titrant solutions are equally concentrated; thus, this...

Weak acids and bases do not undergo dissociation completely, and titrations between these two are rarely studied. When such studies are performed, say, for the titration of a weak acid with a weak base, the titration curve plots the change in pH as a function of the volume of base added. Take the titration of acetic acid with ammonia, for instance. During the titration, these two species form ammonium acetate and water, but the pH change is slow and gradual. As a result, there is no simple...

A solution containing appreciable amounts of a weak conjugate acid-base pair is called a buffer solution, or a buffer. Buffer solutions resist a change in pH when small amounts of a strong acid or a strong base are added. A solution of acetic acid and sodium acetate is an example of a buffer that consists of a weak acid and its salt: CH3COOH (aq) + CH3COONa (aq). An example of a buffer that consists of a weak base and its salt is a solution of ammonia and ammonium chloride: NH3 (aq) + NH4Cl...

Buffers When an Arrhenius acid (HA) is added to water, it dissociates into its conjugate base (A-) and a hydrogen cation (H+). HA + H2O → H+(aq) + A-(aq) The amount of hydrogen ions present in the solution determines the acidity of the solution, where more hydrogen ions indicate a lower or more acidic pH. Similarly, when a strong Arrhenius base (BOH) is added to water, it dissociates into its conjugate acid (B+) and a hydroxide ion (OH-). BOH + H2O → B+(aq) + OH-(aq) Generally, the addition of...