# Activity in Chemical Equilibrium (Oxley)

- Page ID
- 281990

Learning Objectives

After completing this exercise, students will be able to:

- Calculate the ionic strength of a solution.
- Determine the activity coefficient for species in solution.
- Perform equilibrium calculations using activity.

- Calculate the solubility of calcium oxalate, CaC
_{2}O_{4}, in (a) water and (b) 0.050 M CaCl_{2}. The*K*_{sp}for CaC_{2}O_{4}is 1.3 x 10^{-8}.

- Calculate the ionic strength of a solution containing 0.050 M CaCl
_{2}.

- Would an equimolar solution of NaCl or CaCl
_{2}have a higher ionic strength? Explain.

- Calculate the solubility of calcium oxalate, CaC
_{2}O_{4}, in 0.050 M CaCl_{2}, including activity coefficients in your calculation. The*K*_{sp}for CaC_{2}O_{4}is 1.3 x 10^{-8}.

- What is the relative error resulting from neglecting activities in calculating the solubility of CaC
_{2}O_{4}in a 0.050 M solution of CaCl_{2}?

- What is the relative error resulting from neglecting activities in calculating the pH of a 0.100 M HCl solution?

## Contributors and Attributions

- Susan Oxley, St. Mary’s University (San Antonio) (soxley@stmarytx.edu)
- Sourced from the Analytical Sciences Digital Library