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 of acetate ions

Explanation:

Given parameters:

Mass of Ba(C₂H₃O₂)₂  = 69g

Volume of water  = 970mL  = 0.97dm³

Molar mass of Ba(C₂H₃O₂)₂ = 255.415g/mol

Unknown:

Concentration of acetate ion in the final solution = ?

Solution:

Let us represent the dissociation;

                Ba(C₂H₃O₂)₂  = Ba²⁺   + 2C₂H₃OO⁻

We see that 1M of will produce 2M of acetate ions

Now, let us find the molarity of the barium acetate;

            Molarity  = $\frac{number of moles }{volume}$

                Number of moles of Ba(C₂H₃O₂)₂ = $\frac{mass}{molar mass}$

                Number of moles  = $\frac{69}{255.415}$  = 0.27moles

     Molarity of Ba(C₂H₃O₂)₂ =  $\frac{0.27}{0.97}$   = 0.28M

since 1M of Ba(C₂H₃O₂)₂ will produce 2M of acetate ions

        0.28M of Ba(C₂H₃O₂)₂ will produce 2 x 0.28  = 0.56M of acetate ions