Question

(1) Write the net ionic equation for the reaction that occurs when equal volumes of 0.233 M aqueous acetylsalicylic acid (aspirin) and aniline are mixed. It is not necessary to include states such as (aq) or (s).

Answer 1

Check the explanation

Step-by-step explanation:

Ka for aspirin =
`3.0 X 10^(-4)`

Therefore,

pKa = - log(
`3.0 X 10^(-4)`) = 3.52

Kb for Triethylamine = 5.2 x 10-4

Therefore,

pKb = -log(
`5.2 X 10^(-4)`) = 3.28

We have,

pKa + pKb = 14

pKa = 14 – pKb = 10.71

pKa for the triethylammonium salt = 10.71

The net ionic reaction can be written as,

`HC_9H_7O_4 + (C_2H_5)3_N` ⇒
`C_9H_7O_4- + (C_2H_5)_3NH+`

Since pKa of Aspirin is lower (3.52) than that of triethylammonium salt (10.71), at equilibrium triethyl amine will be favored.

pH of equimolar solution can be calculated as,

pH = ½ (pKw + pKa –pKb) = ½ (14 + 3.52 – 3.28) = 7.12

pH of resulting solution = 7.12

Answer 2

Complete Question

The complete question is shown on the first uploaded image

Answer:

1) The ionic equation is

`HC_9H_7O_4 + (C_2 H_5)_3 N -----> C_9H_7O_4^- + (C_2 H_5)_3 NH^-`

2

At equilibrium The aniline will be favored

3

The pH of the solution is
`pH = 7.12`

Step-by-step explanation:

From the question we are told that

The concentration of aspirin is
`C_A = 0.233M`

The acid dissociation constant for aspirin is
`K_a = 3.0*10^(-4)`

The base dissociation constant for aniline is
`K_b = 7.4 *10^(-10)`

The molecular formula for aspirin is
`HC_9H_7O_4`

The molecular formula for aniline is
`(C_2 H_5)_3 N`

So the net ionic reaction is

`HC_9H_7O_4 + (C_2 H_5)_3 N -----> C_9H_7O_4^- + (C_2 H_5)_3 NH^-`

Generally pKa is mathematically evaluated as

`pKa = -log(3.0*10^(-4))`

`= 3.52`

Generally pKb is mathematically represented as

`pKa = -log(7.4*10^(-10 ))`

`= 9.13`

Generally

pKa + pKb = 14

So for the triethylammonium salt produced the pKa is

`pK_a__(s)} = 14 - 3.28`

`= 10.72`

As a result of the pKa of aspirin being lower that that of triethylammonium salt at equilibrium it implies that aniline would be favored

The pH of the solution is mathematically represented as

Since they are of equal mole

`pH = (1)/(2) (pKa + pKb + pKw)`

Where pKw is the pKw of water which has a value of 14

`pH = 0.5(14 + 3.52 + 3.28)`

`pH = 7.12`