Answer to Question #86137 in General Chemistry for mike

Question

In the laboratory you dissolve 22.1 g of chromium(III) acetate in a volumetric flask and add water to a total volume of 500 mL.

What is the molarity of the solution? _______ M.

What is the concentration of the chromium(III) cation? ______ M.

What is the concentration of the acetate anion?__________ M

Answer 1

Dissociation of the salt:

Cr(CH₃COO)₃->Cr³⁺+3CH₃COO^-

i) Find molarity of the solution:

n=m/M

n(Cr(CH₃COO)₃=22.1g/229.15g/mol=0.0964mol

c=0.0964mol/0.5L=0.193mol/L=0.193M

ii) According to equation 1mole of Cr(CH₃COO)₃ gives 1 mole of Cr³⁺, then n(Cr³⁺)=n(Cr(CH₃COO)₃)=0.0964mol

c(Cr³⁺)=0.0964mol/0.5L=0.193mol/L=0.193M

iii) According to equation 1mol of Cr(CH₃COO)₃ gives 3 moles of CH₃COO^-, then n(CH₃COO^-)=3*n(Cr(CH₃COO)₃)=3*0.0964=

0.289mol

c(CH₃COO^-)=0.289mol/0.5L=0.579mol/L=0.579M.