Question

There are three ways in which to define acids and bases: the Arrhenius concept, the Brønsted-Lowry concept, and the Lewis concept. Arrhenius acids are substances that, when dissolved in water, increase the concentration of the H+ ion; Arrhenius bases are substances that, when dissolved in water, increase the concentration of the OH− ion. Brønsted-Lowry acids are substances that can donate a proton (H+) to another substance; Brønsted-Lowry bases are substances that can accept a proton (H+). A Lewis acid is an electron-pair acceptor, and a Lewis base is an electron-pair donor. Part A Using the Arrhenius concept of acids and bases, identify the Arrhenius acid and base in each of the following reactions: 2KOH(aq)+H2SO4(aq)→K2SO4(aq)+2H2O(l) NH3(g)+HCl(g)→NH4Cl(s)

Answer 1

(a)
`KOH` acts as base.

`H_2SO_4` acts as acid.

(b)
`NH_3` acts as base.

`HCl` acts as acid.

Step-by-step explanation:

Arrhenius theory:-

The Arrhenius theory was introduced introduced by Swedish scientist named Svante Arrhenius in 1887.

According to the theory, acids are the substances which dissociate in the aqueous medium to produce electrically charged atoms ( may be molecule). Out of these species furnished, one must be a proton or the hydrogen ion,
`H^+`.

Base are the substances which dissociate in the aqueous medium to produce electrically charged atoms ( may be molecule). Out of these species furnished, one must be a hydroxide ion,
`OH^-`.

Thus, according to the reaction:-

(a)

`2KOH_((aq))+H_2SO_4_((aq))\rightarrow K_2SO_4_((aq))+2H_2O_((l))`

`KOH` dissociates as:-

`KOH\rightarrow K^++OH^-` and hence, acts as base.

`H_2SO_4` dissociates as:-

`H_2SO_4\rightarrow 2H^++SO_4^(2-)` and hence, acts as acid.

(b)

`NH_3_((g))+HCl_((g))\rightarrow NH_4Cl_((s))`

`NH_3` dissociates as:-

`NH_3+H_2O\rightarrow NH_4^++OH^-` and hence, acts as base.

`HCl` dissociates as:-

`HCl\rightarrow H^++Cl^(-)` and hence, acts as acid.