3. Sulfite is a compound frequently added to preserve food and wine. In addition to inhibiting bacteria, it also prevents the oxidation of ethanol into acetic acid! a. It was previously discussed that sulfate, SO4 2– , can be categorized as a negligible base. Sulfite, SO3 2– , however, is basic. Considering the two structures, why is sulfite significantly more basic? b. Write the chemical equation and the equilibrium constant expression for the reaction between SO3 2– and water. c. Sulfurous acid, H2SO3 has a Ka1 = 1.23 x 10–2 and a Ka2 = 6.60 x 10–8 at 25 ºC. What is the pH of a 0.50M solution of Na2SO3?

a)  The detailed explanation for the question being asked in section a is shown below

b)

    Equilibrium constant expression  

c) pH = 10.45

Explanation:

a.

If we look at , we will realize that it is a conjugate base of a strong acid . However, the more stronger the acid, the weaker its conjugate base.

On the other hand is a conjugate base of a weak acid and the more weaker the acid, the stronger the basicity of its conjugate base.

b. The chemical equation for the reaction between  and water can be expressed as follows:

Equilibrium constant

c.

The ICE Table is then constructed as follows:

Initial  (M)              0.500                                                 0                 0

Change  (M)           - x                                                      + x               + x

Equilibrium  (M)   (0.500 - x)                                             x                x

where is the ionic product of water =

However;

      since value is so small; then (0500 -x ) ≅ 0.500

pH + pOH = 14

pH + 3.55 = 14

pH = 14 - 3.55

pH = 10.45

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.