Problem broken down into 4 individual questions. Part 1 of 4: Supply the calcula

Question

Problem broken down into 4 individual questions.

Part 1 of 4:

Supply the calculated molarities of the indicated species in the solution mixtures.Assume the solutions are at 25 degrees Celsius.

Problem #C1: Calculate the Molarities for: HC2H3O2 , C2H3O2-, H+

Given the following procedure (straight from lab book).

C. pH of Buffer Solutions:
1. Preparation of Buffer Solution: Weigh 3.3 g of solid sodium acetate trihydrate, NaC2H3O2 * 3H2O, into a clean 150 or 250 mL beaker. Using graduated cylinders, add 46 mL of deionized water and 4.0 mL of 6.0 M HC2H3O2. Mix thoroughly. Measure 19.0 mL of this into each of two clean beakers. Label as "A" and "B". Measure the pH of this buffer solution using the remaining 10 mL.

Explanation / Answer

moles of sodium acetate trihydrate = 3.3 / 136.08 = 0.024

molarity = moles / total volume

            = 0.024 / (46+4)

             = 4.85 x 10^-4 M

molarity of CH3COOH = 4 x 6.0 / (46+4)

                                    = 0.48 M

HC2H3O2 = 0.48 M

   C2H3O2-   = 4.85 x 10^-4 M

HC2H3O4 ---------------------> C2H3O4- + H+

Ka = [ C2H3O4-][H+]/[HC2H3O4 ]

1.8 x 10^-5 = 4.85 x 10^-4   x [H+] / 0.48

[H+] = 0.0178 M

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.