Question

What is the final acetate ion concentration when 69. g Ba(C2H3O2)2 is dissolved in enough water to make 970. mL of solution? The molar mass of Ba(C2H3O2)2 is 255.415 g/mol.
0.28 M
0.64 M
0.91 M
0.20 M
0.56 M

Answer 1

Answer:

• 0.56M

Explanation:

1. Dissociation equation

Assuming 100% dissociation, the equation is:

• Ba(C₂H₃O₂)₂    →   Ba²⁺   +   2C₂H₃O₂⁻

                                                          ↑

                                                    acetate ions

2. Molarity

Calculate the molarity, M, of the solution:

• M = n / V(in liters)

• n = mass in grams / molar mass

• n = 69.g / 255.415g/mol = 0.27015 mol

• M = 0.27015mol / 0.970liter = 0.27850 mol/liter ≈ 0.28M

3. Acetate ions

From the chemical equation, 1 mol of dissolved Ba(C₂H₃O₂)₂ produces 2 acetate ions in solution.

Thus, 0.28 mol/liter × 2 = 0.56 mol/liter = 0.56M ← answer