In-class Problem Set #3
- Page ID
- 70805
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Problem #1
After completing this problem, the student will be able to:
- Write the appropriate reactions and equilibrium constant expressions for a solution of a polyprotic acid
- Write an expression for the concentration of H3O+ in terms of other species produced by the dissociation of the acid
- Explain why the first reaction in the sequence is much more significant than any subsequent reactions in the stepwise dissociation of a solution of a polyprotic acid
- Solve for the pH of the solution of a polyprotic acid
Problem #2
After completing this problem, the student will be able to:
- Write the appropriate reactions and equilibrium constant expressions for a solution of a polybasic compound
- Determine the Kb values for each reaction in the series
- Explain why the first reaction in the sequence is much more significant than any subsequent reactions in the stepwise reaction of a polybasic compound
- Solve for the pH of the solution of a polybasic compound
- Name polyprotic acids as well as the other species in the series of reactions that represent the dissociation of a polyprotic acid.
Problem #3
After completing this problem, the student will be able to:
- Determine the concentration of species in a solution of a polybasic compound that has a quantity of strong acid added to it
- Determine the concentration of species in a solution of a polyprotic acid that has a quantity of strong base added to it
- Explain why a polyprotic system can be used to prepare more than one buffer, each of which is centered around the different pKa values for the polyprotic acid
- Solve for the pH of the solution prepared by adding a strong acid to a polybasic compound or strong base to a polyprotic acid
Problem #4
After completing this problem, the student will be able to:
- Determine the redistribution of species that occurs when phosphoric acid is mixed with sodium phosphate
- Show that the redistribution of species that occurs in learning objective 1 usually leads to the formation of a buffer
- Solve for the pH when two or more species in a polyprotic acid system are mixed together in solution
Problem #5
After completing this problem, the student will be able to:
- Write an expression for the concentration of H3O+ in terms of other species of a polyprotic acid system when the initial solution is prepared using on an intermediate species
- Derive an expression for H3O+ using the appropriate Ka expressions and the expression written in learning objective #1.
- Show that, in most circumstances, the pH of a solution prepared using only an intermediate species is the average of the two appropriate pKa values