What is the concentration of nitrate ions in a 0.125 M Mg(NO3)2 solution?

• A. 0.125 M
• B. 0.250 M
• C. 0.0625 M
• D. 0.375 M

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of the compound: magnesium nitrate is Mg(NO\_3)\_2, which means each formula unit contains 1 Mg\^{2+} ion and 2 nitrate (NO\_3\^-) ions.
2. Understand that the concentration given (0.125 M) refers to the concentration of Mg(NO\_3)\_2 formula units in solution.
3. Since each formula unit produces 2 nitrate ions, multiply the molarity of Mg(NO\_3)\_2 by 2 to find the nitrate ion concentration.
4. Write the expression for nitrate ion concentration: \([\text{NO}_3^-] = 2 \times [\text{Mg(NO}_3)_2]\).
5. Substitute the given molarity into the expression to find the nitrate ion concentration (do not calculate the final value here).