Theories of acids and bases
3 marks · EasyThe table shows whether these reactions occur in water according to the Arrhenius and Bronsted-Lowry theories.
| Reaction | Explained by Arrhenius? | Explained by Bronsted-Lowry? |
|---|---|---|
| HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) | Yes | Yes |
| NH3(aq) + H2O(l) → NH4+(aq) + OH-(aq) | No | Yes |
| HCl(g) + NH3(g) → NH4Cl(s) | No | Yes |
According to the table, which theory can explain all three reactions?
Which reaction(s) are explained only by the Bronsted-Lowry theory, not the Arrhenius theory?
State one key difference between the two theories based on the reactions above.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) Bronsted-Lowry theory
(b) 2 and 3 (NH3 + H2O, HCl + NH3)
(c) Arrhenius only applies to aqueous reactions; Bronsted-Lowry applies to reactions outside water.
Common mistakes: Confusing coverage of each theory
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies Bronsted-Lowry theory as explaining all three reactions.
B2 (b) · 1 mark · Identifies reactions 2 and 3 as explained only by Bronsted-Lowry, not Arrhenius.
B3 (c) · 1 mark · States a difference: Arrhenius only explains aqueous reactions; Bronsted-Lowry applies more generally or outside aqueous solution.
Worked solution
a) Bronsted-Lowry theory explains all three reactions.
b) Reactions 2 and 3 (NH_3 + H_2O and HCl + NH_3) are explained only by Bronsted-Lowry.
c) The Arrhenius theory is limited to aqueous solutions, but the Bronsted-Lowry theory applies to more situations, including non-aqueous reactions.