Converters & Calculators
Acid and Base Chart: Concise Reference for Quantitative Acid and Base Strength and Reactivity Parameters
Description
This document provides a concise guide to the acid and base chart. The document explains the function of acids, bases and salts in daily scientific practice and industrial processes.
Acids, Bases, and Salts
Acids typically exhibit a sour taste and may cause burns or skin irritation. For example, vinegar and lemon juice are acids encountered routinely. Bases characteristically present a bitter taste and a slippery feel. Soap is an example of a base that is frequently used. Salts are produced when acids and bases react. Table salt (sodium chloride) is an example of a salt. The chart quantitatively displays the strength of various acids and bases and details the neutralisation reactions between them. This document provides representative examples to illustrate these concepts.
Summary Table: Strength of Acids and Bases
|
Acids/Bases |
Formula |
Approx. pKa |
Notes |
|
Strong Acids |
|||
|
Hydrochloric acid |
HCl |
–7 |
Mineral acid that ionises completely in aqueous solution. |
|
Sulphuric acid (1st H) |
H₂SO₄ |
–9 |
Diprotic acid; only the first dissociation is complete. |
|
Nitric acid |
HNO₃ |
–1.4 |
Oxidising acid that ionises completely in water. |
|
Hydrobromic acid |
HBr |
–9 |
Acid that ionises completely in aqueous solution. |
|
Hydroiodic acid |
HI |
–10 |
Acid that ionises completely in water. |
|
Perchloric acid |
HClO₄ |
–10 |
Among the acids with complete ionisation in aqueous solution. |
|
Weak Acids |
|||
|
Acetic acid |
CH₃COOH |
4.76 |
Found in vinegar. |
|
Carbonic acid |
H₂CO₃ |
6.35 (1st) |
Forms in the CO₂–water equilibrium. |
|
Hydrofluoric acid |
HF |
3.17 |
Weak acid, notably corrosive. |
|
Phosphoric acid |
H₃PO₄ |
2.15 (1st) |
Triprotic acid; only the initial dissociation is complete. |
|
Formic acid |
HCOOH |
3.75 |
Present in insect venom. |
|
Citric acid |
C₆H₈O₇ |
~3.1 |
Organic triprotic acid. |
|
Strong Bases |
|||
|
Sodium hydroxide |
NaOH |
~0 |
Common strong base that ionises completely in water. |
|
Potassium hydroxide |
KOH |
~0 |
Common strong base that ionises completely in water. |
|
Calcium hydroxide |
Ca(OH)₂ |
~1.4 |
Sparingly soluble in water. |
|
Barium hydroxide |
Ba(OH)₂ |
~0.15 |
Strong base with high water solubility. |
|
Weak Bases |
|||
|
Ammonia |
NH₃ |
4.75 |
Common weak base. |
|
Methylamine |
CH₃NH₂ |
3.36 |
Simple organic base. |
|
Pyridine |
C₅H₅N |
8.75 |
Aromatic heterocyclic base. |
|
Aniline |
C₆H₅NH₂ |
9.4 |
Aromatic amine; weak base. |
|
Bicarbonate ion |
HCO₃⁻ |
~7.6 |
Amphoteric ion; component of a buffering system. |
Further reading: PH Scale: Acids, Bases, and Common Materials
The table below provides a summary of common acids and bases accompanied by their measured strength. The scale of strength generally ranges from weak to strong. The content is outlined here:
• Strong Acids: For example, hydrochloric acid and nitric acid are included. These acids ionise completely in water, thereby leading to significant modifications in pH.
• Weak Acids: For example, acetic acid and citric acid are included. These acids do not fully dissociate in water and exhibit lower reactivity relative to strong acids.
• Strong Bases: For example, sodium hydroxide and potassium hydroxide are included. These bases completely dissociate in water, yielding high pH solutions.
• Weak Bases: For example, ammonium hydroxide is included. Such bases partially dissociate in water and display lower reactivity than strong bases.
This summary table outlines the relative reactivities and strengths. Each entry is determined by the percentage ionisation in aqueous solution and the associated pH level.
Understand Acid-Base Relationships
Acids and bases operate in conjugate pairs. When combined, they undergo neutralisation, thereby producing water and a salt. This reaction is essential in various natural processes and industrial applications. For example, the human stomach utilises hydrochloric acid to decompose food. Additionally, bases are employed to neutralise spills. The chart quantitatively presents the balance between acids and bases and indicates the reaction strength between them. This chart assists students and researchers in correlating pH fluctuations with chemical reactions.
How Acid-Base Pairs Stabilize PH
Acid–base pairs contribute to pH stabilisation. Buffer systems utilise these pairs, thereby resisting rapid pH fluctuations. In biological systems, buffers maintain blood pH within a narrow range. The chart illustrates the functioning of acid–base pairs. In various chemical processes, buffers mitigate small pH variations. This characteristic is significant for industrial processes that demand controlled pH conditions. A stable pH facilitates efficient chemical reactions. The table data is presented with concrete examples, and the acid–base interactions are clearly displayed.
Conclusion
The acid and base chart is an effective tool for professionals in the chemical sciences. It quantitatively distinguishes differences in strength and reactivity. Understanding the chart enables informed handling of acids and bases. For further information and technical support, please consult Stanford Advanced Materials (SAM).
Frequently Asked Questions
F: What does a strong acid do when dissolved in water?
Q: It ionises almost completely, thereby yielding a high concentration of hydrogen ions.
F: What is a buffer solution?
Q: It is a mixture of acid–base pairs that resists fluctuations in pH.
F: Why is pH stability important?
Q: pH stability ensures that chemical reactions proceed safely and that biological systems function correctly.
Chin Trento
