What is the concentration in mmol/L of a Ca2+ solution that is 2.50 meq/L?
The Correct Answer and Explanation is:
To convert the concentration of Ca2+\text{Ca}^{2+}Ca2+ in meq/L to mmol/L, we need to understand the relationship between milliequivalents (meq) and millimoles (mmol).
- Understanding Equivalents and Moles:
- The term equivalent refers to the amount of a substance that will combine with or replace 1 mole of hydrogen ions (H+) or 1 mole of electrons. For ions like Ca2+\text{Ca}^{2+}Ca2+, the equivalent corresponds to its valence (charge).
- The valence of Ca2+\text{Ca}^{2+}Ca2+ is 2 because it carries a charge of +2.
- Conversion Factor:
- 1 equivalent (eq) of Ca2+\text{Ca}^{2+}Ca2+ is equal to 1 mole of Ca2+\text{Ca}^{2+}Ca2+ ions divided by its valence (which is 2). Therefore: 1 eq of Ca2+=1 mole of Ca2+÷21 \text{ eq of } \text{Ca}^{2+} = 1 \text{ mole of Ca}^{2+} \div 21 eq of Ca2+=1 mole of Ca2+÷2
- To convert from meq (milliequivalents) to mmol (millimoles), we use the fact that: 1 meq of Ca2+=12 mmol of Ca2+1 \text{ meq of } \text{Ca}^{2+} = \frac{1}{2} \text{ mmol of Ca}^{2+}1 meq of Ca2+=21 mmol of Ca2+ This is because 1 meq corresponds to 11000\frac{1}{1000}10001 of an equivalent, and each equivalent corresponds to half a mole of Ca2+\text{Ca}^{2+}Ca2+.
- Calculation:
- You are given a concentration of 2.50 meq/L for the Ca2+\text{Ca}^{2+}Ca2+ solution.
- To convert this to mmol/L: Concentration in mmol/L=2.50 meq/L×12=1.25 mmol/L\text{Concentration in mmol/L} = 2.50 \text{ meq/L} \times \frac{1}{2} = 1.25 \text{ mmol/L}Concentration in mmol/L=2.50 meq/L×21=1.25 mmol/L
Thus, the concentration of Ca2+\text{Ca}^{2+}Ca2+ in the solution is 1.25 mmol/L.
