According to bronsted- Lowry theory , an acid is
Answers
Answer:
According to Bronsted-Lowry theory, acid is a substance which donates an H+ ion or a proton and forms its conjugate base and the base is a substance which accepts an H+ ion or a proton and forms its conjugate acid.
Explanation:
Theory?
The Bronsted-Lowry theory (Proton theory of acid and base) is an acid-base reaction theory, introduced by Johannes Nicolaus Bronsted (Danish Chemist) and Thomas Martin Lowry (English Chemist) in 1923. According to the theory, acid and base react with each other and by an exchange of proton acid, forms its conjugate base and the base forms its conjugated acid.
The Bronsted-Lowry theory is an extended version of an Arrhenius theory of acid-base.
According to the Arrhenius theory, in aqueous solution, acid increases the concentration of H+ ions and base increases the concentration of OH– ions. The limitations of Arrhenius theory was, it identifies the reaction of an acid and base only in the aqueous medium.
Bronsted-Lowry Theory of Acid and Base
According to Bronsted-Lowry theory, acid is a substance which donates an H+ ion or a proton and forms its conjugate base and the base is a substance which accepts an H+ ion or a proton and forms its conjugate acid.
Bronsted-Lowry Acid
The Bronsted-Lowry acid is a substance which donates a proton or H+ ion to the other compound.
Acid \rightleftharpoons Proton + Conjugate baseAcid⇌Proton+Conjugatebase
A conjugate base can accept a proton and acid reforms.
HF \rightleftharpoons H^{+} + F^{-}HF⇌H
+
+F
−
H_{2}SO_{4} \rightleftharpoons H^{+} + HSO_{4}^{-}H
2
SO
4
⇌H
+
+HSO
4
−
NH_{4}^{+} \rightleftharpoons H^{+} + NH_{3}NH
4
+
⇌H
+
+NH
3
H_{2}O \rightleftharpoons H^{+} + OH^{-}H
2
O⇌H
+
+OH
−
F^{-} + H^{+} \rightleftharpoons HFF
−
+H
+
⇌HF
Bronsted-Lowry Base
The Bronsted-Lowry base is a substance which accepts a proton or H+ ion from other compounds.
Base + Proton \rightleftharpoons Congated acidBase+Proton⇌Congatedacid
A conjugated acid can donate a proton and base reforms.
OH^{-} + H^{+} \rightleftharpoons H_{2}OOH
−
+H
+
⇌H
2
O S^{2-} + H^{+} \rightleftharpoons HS^{-}S
2−
+H
+
⇌HS
−
CO_{3}^{2-} + H^{+} \rightleftharpoons HCO_{3}^{-}CO
3
2−
+H
+
⇌HCO
3
−
The Bronsted-Lowry theory of an acid-base reaction involves the transfer of protons or H+ ions between the acid and base.
Example 1:
Consider a reaction in which ammonia (base) is dissolved in water (acid). Ammonia takes a proton from water and the reaction is as follows,
H_{2}O(l)) + NH_{3}(Aq)) \rightleftharpoons OH^{-}(Aq) + NH_{4}^{+}H
2
O(l))+NH
3
(Aq))⇌OH
−
(Aq)+NH
4
+
Acid + Base \rightleftharpoons Conjugate base + conjugate acidAcid+Base⇌Conjugatebase+conjugateacid
Example 2:
A reaction between acetic acid and water, acetic acid donates a proton and acts like acid and water molecule (base) takes a proton.
CH_{3}CO_{2}H (aq) + H_{2}O \rightleftharpoons CH_{3}CO_{2}^{-} + H_{3}O^{+}CH
3
CO
2
H(aq)+H
2
O⇌CH
3
CO
2
−
+H
3
O
+
Acid + Base \rightleftharpoons conjugate base + conjugate acidAcid+Base⇌conjugatebase+conjugateacid
Note:
Strong Bronsted-Lowry acids are those which have a strong tendency to give a proton and their corresponding conjugate base is weak.
Weak Bronsted-Lowry acids will have a little tendency to donate a proton and their corresponding conjugated base is strong.
The Bronsted-Lowry acids and their Conjugated Bases
The strength of the acid decreases as it descends and the strength of their corresponding conjugate base increases.
- Bronsted-Lowry acids are substances that donate protons or H+ ions to other compounds.
- The conjugate base can accept a proton to form an acid.
- The Brønsted-Lowry theory (proton theory of acids and bases ) is a theory of the acid-base reaction introduced into 1923 by Johannes Nikolaus Brønsted (Danish chemist ) and Thomas Martin Lowry (British chemist ) .
- According to the theory , acids and bases react with each other to form to conjugate bases by exchanging acid and base protons to form to conjugate acids .
- The Bronsted-Lowry theory is an improved version of the Arrhenius acid-base theory .
- According to the Arrhenius theory , acids in aqueous solutions increase the concentration of H ions , and bases to increase the concentration of OH- ions .
- A limitation of the Arrhenius theory is that it only identifies acid-base reactions against an aqueous environment .
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