The difference between acids and bases is mainly due to the following factors:-
pH value: Different compounds are having different pH values (1-14), depending upon their chemical nature. The compounds that are having pH less than seven are termed acidic substances, while the compounds that are having a pH of more than seven are termed alkaline substances.
Chemical strength: The strength of an acid and a base depends upon the concentration of hydrogen and hydroxyl ions, respectively.
Taste: It is the most common feature that differentiates the acids and bases through their sour and bitter taste, respectively.
Content: Acids Vs Bases
Comparison Chart
| Properties | Acids | Bases |
|---|---|---|
| Meaning | Acids own a property of giving hydrogen ions in aqueous solutions | Acids own a property of giving hydroxide ions in aqueous solutions |
| Taste | Sour in taste | Bitter in taste |
| Physical state | Depending upon the varying temperature, acids may exist in the form of solid, liquid or gas | Usually exists in the solid-state except for gaseous ammonia |
| pH value | It lies between 0-6 | It ranges between 8-14 |
| Chemical strength | Depends upon the hydrogen ion concentration | Depends upon the hydroxide ion concentration |
| Ionization | On ionization, it forms hydronium ions | On ionization, it forms hydroxyl ions |
| Dissociation | Gives hydrogen ions | Gives hydroxide ions |
| Dissociation constant | Strong acids have dissociation constant -2 | Strong bases have dissociation constant 12 |
| Neutralization reaction | It neutralizes to give salt and water by reacting with bases | It neutralizes to give salt and water by reacting with acids |
| Chemical formula | The chemical formula for acids generally starts with a letter (H) | The chemical formula for bases that ends typically with a letter (OH) |
| Litmus test | Turns the blue litmus to red | Turns the red litmus to blue |
| Phenolphthalein test | Remains colourless | Turns into pink |
| Methyl orange test | Turns red | Turns orange |
| Universal indicator test | Acid turns yellow to red | Acid turns blue to violet |
| Reaction with metals | It reacts with metals to release H2 | It does not react with metals |
| Examples | Hydrochloric acid (HCl), Sulphuric acid (H2SO4) etc. | Sodium hydroxide (NaOH), Potassium hydroxide (KOH) etc. |
Definition of Acid
Acids refer to the molecule or substances that possess the property of giving hydrogen ions in the aqueous solutions that form an acidic solution, whose pH ranges between 1-6. Many scientists have given their different views to explain the term “Acid”:
- As per Arrhenius Concept, acids can elevate the concentration of hydrogen ions when mixed with water.
- According to the Bronsted-Lowry Concept, acids are the proton donating molecules.
- As per Lewis theory, acids acts like an electrophile that accepts the electron pair and possesses vacant orbitals are termed Lewis acid.
Physical and Chemical Characteristics of Acids
- Physical characteristics: The texture of acids is generally sticky, sour in taste and corrosive and conducts electricity.
- Chemical characteristics: Acids turn the blue litmus to red. It neutralizes by the addition of bases and reacts with active metals to liberate hydrogen ions. It remains colourless, by the addition of phenolphthalein.
Classification
- Strong acids: It includes nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl) etc. that completely ionizes in water.
- Strong Lewis acids: It includes AlCl3 (anhydrous aluminium chloride), BF3 (boron trifluoride) etc. that can accept a pair of an electron from the Lewis base.
- Weak acids: It includes acetic acid (CH3COOH), formic acid (CH2O2) etc. that partially ionizes in water.
- Superacids: It includes fluoroantimonic acid (HF: SbF5), fluorosulfuric acid (FSO3H) etc. that have an incredibly high H+ concentration than the strong acids.
Definition of Base
Bases refer to the molecule or substances that possess the property of giving hydroxide ions in the aqueous solutions that form a basic solution, whose pH ranges between 8-14.
- As per Arrhenius Concept, bases can elevate the concentration of hydroxide ions (OH–) when mixed with water.
- On the other hand, bases are the proton accepting molecules according to the Bronsted-Lowry Concept.
- According to the Lewis concept, Bases act like a nucleophile that donates an electron pair and possess a lone pair of electrons is termed Lewis base.
Physical and Chemical Characteristics of Bases
- Physical characteristics: The texture of bases is generally powdery, bitter in taste and exists typically in solid form except for ammonia.
- Chemical characteristics: Bases turn the red litmus to blue. It neutralizes by the addition of acids and do not react with active metals and turns pink, by the addition of phenolphthalein.
Classification
- Concentrated base: It includes NaOH (sodium hydroxide), KOH (potassium hydroxide) etc. that completely dissolves in water.
- Weak bases: These partially dissociates OH– ions in water and includes NH3 (ammonia), Al(OH)3 (aluminium hydroxide) etc.
- Alkali metals: These are strong bases that neutralize the acidic property and includes Li (lithium), Na (sodium), K (Potassium) etc.
- Superbases: It includes metal amides, alkoxides, and C4H9Li (butyllithium) etc. that have a high affinity for protons.
Key Differences Between Acids and Bases
- Acids and bases have a characteristic property of giving hydrogen and hydroxide ions when dissolved in an aqueous solution.
- Taste is one of the most common physical property of acids and bases, in which a former possess a characteristic sour taste and the latter have a bitter taste.
- pH value ranges between 0-14 that measures the acidity or alkalinity of the given solution. When the acids are dissolved in the water, it gives hydrogen ion that makes the solution acidic, i.e. pH less than 7. Oppositely, an alkali gives hydroxide ions when it is mixed with water and makes the solution alkaline, i.e. pH of more than 7.
- A neutralization reaction is the formation of products (salt and water) by the reaction of acid and base, i.e. to neutralize the effect of the acids and bases, the addition of bases and acids is required.
- In science, everything is nomenclated so that we can remind particular things by particular names and chemical formulas. There are different acids and bases, and remembering each of them by mouth is difficult. So, many scientists have given their contribution to define and classify various forms of acid and base. The chemical formula of acids usually begins with the letter ‘H’, while the bases end with the suffix ‘OH’. For instance, HCl (hydrochloric acid) is an acid that starts with a letter H, and NaOH (sodium hydroxide) is a base that ends with a letter OH.
Conclusion
Therefore, we can conclude that acids and bases have a significant impact on our daily starting from the foods we consume (few are acidic, and some are basic). The human body is the best example to understand the effect of acids and bases, which regulates the buffering system to neutralize the H+ ions released from acidic molecules.
On the other hand, the OH– ions released from the bases control the body from becoming too acidic. Thus, the study of both acids and bases is important in every aspect that provides a broad scope in areas like environment, food, chemical, medical science and many other fields.