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Multiple Choice
Calculate the normality (mEq/L) of potassium ions in a 500 mL Ringer's solution that is 2.0 x 10-3 M in potassium ions.
A
2.0 mEq/L
B
0.200 mEq/L
C
2.5 mEq/L
D
0.250 mEq/L
Verified step by step guidance
1
Understand that normality (N) is a measure of concentration equivalent to molarity (M) multiplied by the equivalent factor. For ions, the equivalent factor is the charge of the ion. Potassium ions (K+) have a charge of +1, so the equivalent factor is 1.
Calculate the normality using the formula: \( N = M \times \text{equivalent factor} \). Since the molarity of potassium ions is given as \( 2.0 \times 10^{-3} \) M and the equivalent factor is 1, the normality is \( 2.0 \times 10^{-3} \) N.
Convert the normality from molarity to milliequivalents per liter (mEq/L). Since 1 N is equivalent to 1000 mEq/L, multiply the normality by 1000 to convert it: \( 2.0 \times 10^{-3} \times 1000 \) mEq/L.
Recognize that the volume of the solution does not affect the normality calculation directly, as normality is a concentration measure. Therefore, the normality remains the same regardless of the volume of the solution.
Review the calculated normality and compare it with the given options to identify the correct answer. The calculated normality should match one of the provided choices.