GENERAL PROPERTIES OF ACIDS AND BASES

Quick Quiz

What is the difference between Arrhenius base and Bronsted-Lowry base?
What do you mean by neutralization reaction according to Arrhenius acid-base concept?
Prove that water is an amphoteric specie.
How can you justify that $\text{NH}_3$ is Bronsted-Lowry base but not Arrhenius base?
State and explain the neutralization reaction according to Lewis concept.
Define and give the characteristics of a Lewis acid.
Why $\text{BF}_3$ behaves as a Lewis acid?
Water is an amphoteric specie according to Bronsted-Lowry concept. What is its nature according to Lewis concept?

10.1.4 General Properties of Acids

Physical Properties

Physical properties of acids have been described in the beginning of the chapter.

Chemical Properties

(i) Reaction with Metals

Acids react explosively with metals like sodium, potassium and calcium. However, dilute acids (HCl, $\text{H}_2\text{SO}_4$ ) react moderately with reactive metals like: Mg, Zn, Fe and Al to form their respective salts with the evolution of hydrogen gas.

Z n_{(s)} + H_{2} S O_{4} (a q) \to Z n S O_{4} (a q) + H_{2} (g)

F e_{(s)} + 2 H C l (a q) \to F e C l_{2} (a q) + H_{2} (g)

M g_{(s)} + 2 H C l (a q) \to M g C l_{2} (a q) + H_{2} (g)

2 A l_{(s)} + 3 H_{2} S O_{4} (a q) \to A l_{2} (S O_{4})_{3} (a q) + 3 H_{2} (g)

(ii) Reaction with Carbonates and Bicarbonates

Acids react with carbonates and bicarbonates to form corresponding salts with the evolution of carbon dioxide gas.

N a_{2} C O_{3} (a q) + 2 H C l (a q) \to 2 N a C l (a q) + C O_{2} (g) + H_{2} O (l)

N a H C O_{3} (a q) + H C l (a q) \to N a C l (a q) + C O_{2} (g) + H_{2} O (l)

C a C O_{3} (s) + 2 H C l (a q) \to C a C l_{2} (a q) + C O_{2} (g) + H_{2} O (l)

(iii) Reaction with Bases

Acids react with bases (oxides and hydroxides of metal and ammonium hydroxide) to form salts and water. This process is called neutralization.

N a O H_{(a q)} + H C l_{(a q)} ⟶ N a C l_{(a q)} + H_{2} O_{(l)}

\mathrm{CuO_{(s)} + H_2SO_4_{(aq)}\longrightarrow CuSO_4_{(aq)} + H_2O_{(l)}}

(iv) Reaction with Sulphites and Bisulphites

Acids react with sulphites and bisulphites to form salts with the liberation of sulphur dioxide gas.

<span class="katex-error" title="ParseError: KaTeX parse error: Double subscript at position 15: \mathrm{CaSO_3_̲{(aq)} + 2HCl_{…" style="color:#cc0000"}}>\mathrm{CaSO_3_{(aq)} + 2HCl_{(aq)}\longrightarrow CaCl_2_{(aq)} + SO_2_{(g)}\uparrow + H_2O_{(l)}}

<span class="katex-error" title="ParseError: KaTeX parse error: Double subscript at position 16: \mathrm{NaHSO_3_̲{(aq)} + HCl_{(…" style="color:#cc0000"}}>\mathrm{NaHSO_3_{(aq)} + HCl_{(aq)}\longrightarrow NaCl_{(aq)} + SO_2_{(g)}\uparrow + H_2O_{(l)}}

(v) Reaction with Sulphides

Acids react with metal sulphides to liberate hydrogen sulphide gas.

\mathrm{FeS_{(s)} + H_2SO_4_{(aq)}\longrightarrow FeSO_4_{(aq)} + H_2S_{(g)}\uparrow}