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Chemistry Formula for Salts of Weak Acids and Weak Bases

Salts of weak acids and weak bases are ionic compounds resulting from the reaction between acids and bases, exhibiting only partial ionisation in aqueous solutions. 
authorImageRanvijay Singh28 Oct, 2023
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Salts of Weak Acids and Weak Bases

Salts are an integral part of chemistry, formed through the reaction of acids and bases. Their properties can vary significantly depending on the nature of the acid and the base involved in their formation. Salts of weak acids and bases play a significant role in various chemical processes and industries. They exhibit unique properties that make them valuable in laboratories, pharmaceuticals, food and beverage production, and many other applications. Understanding their chemistry and applications is crucial for professionals working in these fields, as it allows for better control of chemical reactions, pH adjustments, and various other processes that involve these versatile salts.

Understanding Salt Formation

Salts are ionic compounds made up of positively charged ions, known as cations, and negatively charged ions, known as anions. These ions are formed when an acid donates a proton (H+) to a base, which then accepts this proton. The properties of the resulting salt depend on the strength and characteristics of both the acid and the base.

Weak Acids

Weak acids are acids that partially dissociate in water, releasing only a small fraction of their hydrogen ions (H+). Common examples of weak acids include acetic acid CH 3 COOH and carbonic acid (H 2 CO 3) .

Weak Bases

Weak bases, on the other hand, are substances that partially dissociate in water, releasing fewer hydroxide ions (OH-) compared to strong bases. Ammonia (NH3) is a well-known example of a weak base.

Also Check - Salts of Strong Acids and Weak Bases

Salts of Weak Acids and Weak Bases

When weak acids react with weak bases, they form salts known as salts of weak acids and weak bases. The resulting salts exhibit unique properties and characteristics distinct from those formed by strong acids and bases.

Common Examples of Salts of Weak Acids and Weak Bases

Ammonium Acetate (CH 3 COONH 4 ):

  • Formed by the reaction between acetic acid (CH 3 COOH) and ammonia (NH 3 ).
  • Chemical Equation: CH 3 COOH + NH 3 → CH 3 COONH 4

Ammonium Carbonate (NH 4 ) 2 CO 3 :

  • Produced by the combination of carbonic acid ( H 2 C O 3 ) and ammonia (NH 3 ).
  • Chemical Equation: H 2 C O 3 + 2 N H 3 ( N H 4 ) 2 C O 3

Ammonium Citrate (C6H8O7·xNH3):

  • Derived from citric acid (C 6 H 8 O 7 ) and ammonia (NH 3 ).
  • Chemical Equation: C 6 H 8 O 7 + xNH 3 → C 6 H 8 O 7 ·xNH 3

Ammonium Phosphate ((NH4)3PO4):

  • Formed when phosphoric acid (H 3 PO 4 ) reacts with ammonia (NH 3 ).
  • Chemical Equation: H 3 PO 4 + 3 NH 3 → (NH 4 ) 3 PO 4

Ammonium Sulfide ((NH4)2S):

  • Resulting from the combination of hydrogen sulfide ( H 2 S ) and ammonia (NH 3 ).
  • Chemical Equation: H 2 S + 2 N H 3 ( N H 4 ) 2 S

Also Check - Sodium Chlorate Formula

Chemical Characteristics of Salts of Weak Acids and Weak Bases

Salts formed from weak acids and weak bases exhibit unique chemical properties:

Solubility

  • Many salts of weak acids and weak bases are highly soluble in water due to the presence of ions that readily dissociate.

pH

  • The pH of the resulting solution is typically close to neutral. This is because weak acids and weak bases do not significantly affect the concentration of H+ and OH- ions.

Conductivity

  • When dissolved in water, salts of weak acids and weak bases can conduct electricity, as they produce ions that carry electrical charges.

Buffering Capacity

  • Some salts of weak acids and weak bases can act as buffers. They can resist changes in pH when an acid or base is added to the solution, making them useful in various chemical processes.

Also Check - Silver Phosphate Formula

Applications of Salts of Weak Acids and Weak Bases

Salts of weak acids and weak bases have several practical applications in various industries:

Laboratory Reagents

  • These salts are often used in laboratories for chemical reactions, pH adjustments, and buffering.

Pharmaceuticals

  • Some pharmaceutical formulations use salts of weak acids and weak bases to enhance the stability and solubility of drugs.

Food and Beverage

  • Salts like ammonium citrate are used in the food and beverage industry for various purposes, including as a buffering agent in soft drinks.

Photography

  • Ammonium thiosulfate, a salt of weak acids and weak bases, is used in photographic development processes.

Chemical Analysis

  • These salts are employed in analytical chemistry to control reaction conditions and adjust pH levels.

Wastewater Treatment

  • Ammonium compounds are used to neutralize wastewater in industrial processes.

Agriculture

  • Salts of weak acids and weak bases, such as ammonium phosphate, are used as fertilizers to provide essential nutrients to plants.

Salts of Weak Acids and Weak Bases FAQs

Q1. What are the salts of weak acids and weak bases?

Ans. Salts of weak acids and weak bases are ionic compounds formed when a weak acid reacts with a weak base. Common examples include ammonium acetate (CH3COONH4), ammonium carbonate ((NH4)2CO3), ammonium citrate (C6H8O7·xNH3), ammonium phosphate ((NH4)3PO4), and ammonium sulfide ((NH4)2S).

Q2. What is the equation for a weak acid and a weak base?

Ans. The equation for the reaction between a weak acid (HA) and a weak base (BOH) involves the transfer of protons (H+ ions) to form water (H2O) and the conjugate base (A-) of the weak acid. The general equation is: HA + BOH → H2O + A- + B+.

Q3. What is the formula to calculate pH of a salt of weak acid and weak base?

Ans. To calculate the pH of a salt formed from a weak acid and a weak base, you consider the equilibrium expression for the reaction. The pH is determined by the concentration of the ions (H+ and OH-) formed when the salt dissolves in water. For example, in the case of ammonium acetate, the pH can be calculated using the equilibrium expression for the dissociation of its ions.

Q4. What are the 7 weak acids?

Ans. Seven common weak acids include acetic acid (CH3COOH), carbonic acid (H2CO3), citric acid (C6H8O7), hydrofluoric acid (HF), phosphoric acid (H3PO4), formic acid (HCOOH), and hydrogen sulfide (H2S). These weak acids only partially ionize in water, resulting in a relatively low concentration of H+ ions.
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