A.) To keep ionic strength constant and maintain a more consistent matrix in a solution where ions could be influencing each other, another component is often added to the solution. This is an ionic compound, not involved directly with the reaction, called an ionic strength adjuster (ISA) ingredient. What is the ionic strength (I) of a solution that contains 0.0280 M (NH_4)_2_SO_4 as the ISA ingredient?

(NH_4)_2_SO_4(s) --> 2NH_4^+^(aq) + SO_4^2-^(aq)

B.) One particular use of a selective electrode is the determination of the level of Cl^-^ in drinking water. What would be the activity coefficient (%u03B3) for the chloride ion Cl^-^ in the solution from part "A"?

C.) The chemical activity (a) of an ion in the solution is related to the actual concentration of the ion. Which one, if any, of the following statements is actually true?

(i.) The chemical activity of an ion is closest to the actual concentration when the ion concentration is very high.

(ii.) Chemical activity and the activity coefficient are two names that have the same meaning.

(iii.) A substance in its standard state will have a chemical activity of 0.

(iv.) In a solution with high ionic strength in the background, Cl^-^ ions will have less repulsion for each other.

(v.) Actually, none of this is true.