Common Properties Of Acids And Bases With Definitions And Examples
Acids and Bases are the most important group of chemicals in chemistry. They play an important role not only in our lives but in almost all natural systems from oceans to rocks, acids and bases have a part to play. You must have come across acid and bases when you tasted lemon or washed your hands with soaps. Acids are sour and can be dangerously corrosive; bases are slippery and can be corrosive as well. Scientists usually classify substances as acids, bases or neutral. The strength of the acid or base is measured by the pH scale.
What are Acids?
Acids are compounds that give out hydrogen ions or a proton when mixed in an aqueous solution. They turn blue litmus red and have a pH below 7.
An acid then generally has a dissociable proton or hydrogen group. It is called acidic hydrogen that readily dissociates in solution or in presence of bases (Arrhenius Acid). Acids can also be termed as compounds which are hydrogen or proton donors (Bronsted-Lowry acid).
HA + H2O → A- + H3O+
According to Lewis' description of acids, they are compounds which can accept electron pairs (Lewis Acid). Lewis acids broaden the definition of acids and incorporate all those compounds which do not contain any proton but have electron-accepting capacity.
In compounds where the acidic hydrogen is directly attached to an oxygen atom, they are called oxoacids or oxyacids. If the hydrogen is with some other element the name of such a compound has hydro- in the beginning, and ends with -ide. Organic acids usually contain a carboxyl group, -COOH.
The strength of an acid is related to its degree of dissociation in solution.
Table: Inorganic Acids
Table: Organic Acids
What are Bases?
Bases are compounds that give out hydroxyl ions when mixed in an aqueous solution. They turn red litmus blue and have a pH above 7.
A base, therefore, bears a dissociable hydroxyl group or a basic group that dissociates in an aqueous medium (Arrhenius base). Bases are also compounds that can steal or accept hydrogen ions, thus, bases can also be defined as compounds which are hydrogen acceptors (Bronsted-Lowry Base).
Metal hydroxides readily furnish hydroxyl ions in an aqueous solution and are predominantly basic. Alkali metals and some alkaline earth metals form the maximum basic hydroxides.
BOH(aq) → B+ (aq) + OH- (aq)
Lewis model of bases, attributes them as electron pair donors. Thus, compounds need not accept a proton or produce hydroxyl ion to be termed a base, any compound that can donate a pair of electrons can be considered a base (Lewis base).
Table: Base
Neutralisation Reaction
The reaction between acid and base produces salt and the reaction is named as neutralisation reaction. In the reaction, the acid releases the proton while the base is the source of the hydroxyl group. The hydrogen ion and the hydroxyl ion combine to form water molecules. The resultant anion after losing a proton combines with the cation formed from the dissociation of the hydroxyl group from the base to produce the salt (AB).
AH(aq) + BOH(aq) → AB(aq) + H2O(l)
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
One of the simplest neutralisations is the reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH), to form sodium chloride salt (NaCl).
In the reaction between HCl and Mg(OH)2, the salt formed is MgCl2. This is an example of neutralization that takes place when one intake antacids that are bases while suffering from acidity.
2HCl(aq) + Mg(OH)2(aq) → MgCl2(aq) + 2H2O(l)
Metal surfaces with a coating of oxides can be removed by cleaning with acids. Rust or stains developed over iron can be removed by treating it with acid like HCl. The acid reacts with the basic ferrous hydroxide that forms the part of rust to neutralise it, producing ferrous chloride.
Certain similarities between acids and bases that can be pointed out are: both acids and bases release ions in an aqueous solution; both respond to the litmus test and both conduct electricity. When either acid or base is added to water, heat is released (exothermic reaction). It is due to this reason acids or bases should always be poured into the water not the other way around. Pouring acid or base into the water can cause accidents.
Interesting Facts
The sting on ant bite is due to the secretion of an acid called Formic acid.
Vinegar used for cooking has acetic acid.
Guavas have oxalic acid.
Key Features
Arrhenius Acids release hydrogen ion or proton in aqueous solution.
Bronsted-Lowry Acids are proton donor.
Lewis Acids are electron acceptor.
Arrhenius Bases releases Hydroxyl ion in aqueous solution.
Bronsted-Lowry Bases are Proton or hydrogen acceptor.
Lewis Bases are electron donor.
FAQs on What Do All Acids And Bases Have In Common In Chemistry
1. What do all acids and all bases have in common?
All acids and all bases have in common that they form ions in water and affect the concentration of H+ ions in solution. In aqueous solutions:
- Acids increase the concentration of hydrogen ions (H+).
- Bases decrease the concentration of H+ or increase the concentration of hydroxide ions (OH-).
- Both are classified as electrolytes because they conduct electricity in water due to mobile ions.
2. What do all acids have in common in chemistry?
All acids have in common that they donate hydrogen ions (H+) in aqueous solution. According to the Arrhenius definition, an acid increases the concentration of H+ in water.
- They usually start with hydrogen in their formula (e.g., HCl, H2SO4).
- They turn blue litmus paper red.
- They react with metals to produce hydrogen gas.
3. What do all bases have in common in chemistry?
All bases have in common that they produce hydroxide ions (OH-) in water or accept hydrogen ions. According to the Arrhenius definition, a base increases the concentration of OH- in aqueous solution.
- They turn red litmus paper blue.
- They feel slippery in solution.
- They neutralize acids to form salt and water.
4. Do all acids contain hydrogen?
Yes, all acids contain hydrogen because they must be able to produce H+ ions in solution. The presence of ionizable hydrogen is essential for acidic behavior.
- Hydrochloric acid: HCl
- Nitric acid: HNO3
- Acetic acid: CH3COOH
5. What is the difference between acids and bases?
The main difference between acids and bases is that acids donate H+ ions, while bases accept H+ ions or produce OH- ions. According to the Brønsted–Lowry theory:
- Acid = proton (H+) donor.
- Base = proton (H+) acceptor.
6. How do acids and bases behave in water?
Acids and bases behave in water by ionizing to form charged particles that change the solution’s pH. In aqueous solution:
- Acids increase [H+] and have pH < 7.
- Bases increase [OH-] and have pH > 7.
- Pure water has pH = 7 at 25°C.
7. Why do both acids and bases conduct electricity?
Both acids and bases conduct electricity because they produce mobile ions in aqueous solution. Electrical conductivity requires charged particles that can move freely.
- Acids produce H+ and anions.
- Bases produce OH- and cations.
- Strong acids and bases conduct better than weak ones due to greater ionization.
8. What happens when an acid reacts with a base?
When an acid reacts with a base, a neutralization reaction occurs producing salt and water. The key reaction is between H+ and OH- ions:
- Net ionic equation: H+(aq) + OH-(aq) → H2O(l)
- A salt is formed from the remaining ions.
9. Are all acids and bases electrolytes?
Yes, all acids and bases are electrolytes because they form ions in aqueous solution. However, their strength depends on degree of ionization.
- Strong electrolytes: completely ionize (e.g., HCl, NaOH).
- Weak electrolytes: partially ionize (e.g., CH3COOH, NH3).
10. What is the common property of acids and bases in terms of pH?
The common property of acids and bases in terms of pH is that both are measured on the pH scale based on hydrogen ion concentration. The pH scale ranges from 0 to 14 at 25°C.
- Acids have pH < 7.
- Bases have pH > 7.
- pH = −log[H+].
