Overview: Acid and Base Solutions

Acid and Base Solutions

Acid and base solutions are chemical reagents with increased or decreased levels of hydrogen ions and are used to manipulate the pH of a target solution via titration. This process can help create or maintain buffer solutions, which are essential for maintaining the optimal pH of biological systems and an experimental environment. Acid and base solutions can also help isolate and purify biomolecules such as proteins, DNA, and RNA, due to their effectiveness in impacting the solubility, charge, and stability of solutes. Strong acids and bases are also capable of greatly influencing the pH and functionality of a system as they are known to completely dissociate in solution.

Acid and Base Reaction Mechanism:

Acids and bases influence their surroundings by the transfer of hydrogen ions (H+) or hydroxide ions (OH-) into their respective environments. These ions are incredibly interactive and hold a direct influence on the pH of the solution of interest [1]. In the reaction mechanism exhibited by Hydrochloric Acid, as shown in the following equation, Hydrochloric Acid dissociates to form a hydronium ion which can then chemically interact with other species presented in solution while effectively lowering the pH of the system.

       1                 2               3                 4

HCl (aq) + H2O (l) → H3O+ (aq) + Cl- (aq)

Where:

Hydrochloric Acid (1) donates a proton, H+, to water (2), which forms an aqueous hydronium ion (3) and an aqueous chloride ion (4). Here, the chloride ion is the conjugate base of Hydrochloric Acid, while the hydronium ion is the conjugate acid of water. Depending on concentration of Hydrochloric Acid, the pH of a Hydrochloric Acid solution can range from 0 to 3.

 

Like the full dissociation of a strong acid in water, strong bases also fully dissociate in solution, and dramatically increase the pH of the solution throughout the process. In the dissociation mechanism of Sodium Hydroxide, a strong base as shown in the following equation, Sodium Hydroxide dissociates in water to release sodium and hydroxide ions.

       1                 2               3                4

NaOH (s) + H2O (l) → Na+ (aq) + OH- (aq)

Where:

Solid Sodium Hydroxide (1) dissociates completely in water (2), a polar solvent, to produce an aqueous sodium ion (3) and an aqueous hydroxide ion (4). Here, the sodium ion is the conjugate acid of Sodium Hydroxide, while the hydroxide ion is the conjugate base of water. Depending on the concentration of Sodium Hydroxide in solution, the pH of Sodium Hydroxide solution can range from 12-14.

Neutralization:

Due to the full dissociation of all strong acids (into H+) and bases (into OH-) in solutions, they are very effective in neutralizing one another to adjust pH [2]. The reaction between a strong acid and base, such as Hydrochloric Acid and Sodium Hydroxide, is therefore known as a Neutralization Reaction. Neutralization reactions can occur whenever hydroxide ions are presented with hydrogen ions, as they interact with each other to form water, a neutral substance. The following equation can be used to show a neutralization reaction that can effectively lower or increase the initial pH of a solution to a value closer to 7.

       1                 2               3                4

HCI(aq) + NaOH (aq) → NaCI (aq) + H2O (l)

Where:

Hydrochloric Acid Solution (1) and Sodium Hydroxide Solution (2) perform a double-replacement neutralization reaction to form salt (i.e., Sodium Chloride, 3) and excess water (4). Here, the strong acid and base combine completely to form neutral compounds (i.e. H2O), resulting in a pH close to 7.

 

Titration:

Titration is the process in which acid and base solutions are used to adjust the pH of a target solution. In the process of preparation of buffers, or solutions for use in biological experiments, the pH of the solution being formulated often must adhere to a specific pH range directly associated with the requirements for the efficient biological and cellular environment, and thus resulting in successful experimental output. Based on the chemical components of a solution, a strong acid such as hydrochloric acid (HCl) can be used to lower the pH of a solution as HCl undergoes dissociation into hydrogen and chloride ions, which in turn results in effectively increasing the concentration of hydrogen ions in solution. Conversely, a strong base such as sodium hydroxide dissociate into sodium and hydroxide ions, and these hydroxide ions interact with hydrogen ions to produce water, and thus, effectively lowering the pH of the solution.

The concentration of the solution/titrant used for adjusting the pH/ titration must be carefully assessed prior to conducting titration, as higher concentrations have a much more dramatic effect on the resulting pH of the solution [3]. It is also worth considering that the dissociated species within the solution of interest must be able to chemically interact with a titrant solution to maximize results.

AcidBase_Titration

 

Image 1: Titration is a process in which an acid or base solution Titrant is added to another substance, effectively decreasing, or increasing the substance's pH value. 

Strong Acids and Bases

Acids and bases often are found in two categories. Strong acids and bases, and weak acid and bases. Strong acids and bases are known to fully dissociate in solution, resulting in a more drastic change in pH, while weaker species do not fully dissociate in solution, and therefore are not as useful as a titrant. For this reason, strong acids and bases are often diluted to create acid and base solutions. Common titrants can be seen below.

Acid or Base

Description
Strong Acids
Hydrochloric Acid (HCl) Hydrochloric Acid, often referred to as muriatic acid, is a corrosive and strong acid widely used in various industrial processes and laboratory settings. It plays a crucial role in chemical synthesis and pH regulation. Exercise caution due to its corrosive nature.
Sulfuric Acid (H2SO4) Sulfuric Acid is a highly reactive and strong acid extensively utilized in diverse industrial applications, including chemical manufacturing, metal processing, and as a laboratory reagent. Its corrosive properties make proper handling essential for safety.
Nitric Acid (HNO3) Nitric Acid is a potent oxidizing acid known for its role in laboratory experiments and the production of various chemicals. It requires careful handling due to its corrosive and reactive nature.
Strong Bases
Sodium Hydroxide (NaOH) Sodium Hydroxide is a strong base used in the manufacturing of soaps, detergents, and various industrial processes. It is highly corrosive and can cause severe burns, emphasizing the importance of safety precautions during use.
Potassium Hydroxide (KOH) Potassium Hydroxide is a powerful alkali employed in the production of soaps, and as a catalyst in chemical reactions. It poses significant risks due to its corrosiveness, necessitating careful handling and protective measures to prevent exposure.
Calcium Hydroxide (Ca(OH)2) Calcium Hydroxide is a white, crystalline solid used in applications such as water treatment, food processing, and construction. Its alkaline properties contribute to its effectiveness in various industrial and commercial processes.

Acid and Base Solutions at Boston BioProducts

Every Acid or Base Solution is unique to its intended application. Experience a variety of acid and base solution types, and choose the correct one for your workflows in terms of ionic species, pH requirements and concentration by exploring custom manufacturing options at Boston BioProducts, or our off-the-shelf  Acid & Base Solution products.

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