Practice Problems for Cation Exchange Capacity
Agronomy 354

1. What is the valence of Ca and what is its milliequivalent weight if the atomic weight is 40?

2. If a soil has 20 meq of CEC/100 g, how many milligrams of Ca2+ will this equal? How many grams?

3. If a soil contains 5% organic matter and 10% kaolinite clay, what is a reasonable estimate of its CEC per 100 g?

4. A soil has a CEC of 24 meq/100 g.  How many grams of Na+ will it take to saturate the CEC?  (At wt Na+ = 23)

5. If a soil can hold 50 mg of Mg2+ per 100 g, how many mg of K+ could it hold?

6. A quantity of 100 g of soil has a CEC of 5 meq. How many negatively charged sites does this soil have?

7. A soil was determined to have 12.5 meq/100 g of CEC. How many cmole/kg would this equal?

8. Convert the following concentrations into parts per million:
At wts:  Ca2+ = 40, H+ = 1, Mg2+ = 24, K+ = 39

10 meq Ca/100 g soil

1 meq H/100 g soil

2 meq Mg/100 g soil

2 meq K/100 g soil

9. Convert 3 cmol/kg soil Ca2+ into parts per million (ppm).