As a chemist for an agricultural products company, you have just developed a new

Question

As a chemist for an agricultural products company, you have just developed a new herbicide,"Herbigon," that you think has the potential to kill weeds effectively. A sparingly soluble salt, Herbigon is dissolved in 1 Macetic acid for technical reasons having to do with its production. You have determined that the solubility product Ksp of Herbigon is 9.10Ý10?6.
Although the formula of this new chemical is a trade secret, it can be revealed that the formula for Herbigon is X-acetate (XCH3COO, where "X" represents the top-secret cation of the salt). It is this cation that kills weeds. Since it is critical to have Herbigon dissolved (it won't kill weeds as a suspension), you are working on adjusting the pH so Herbigon will be soluble at the concentration needed to kill weeds. What pH must the solution have to yield a solution in which the concentration of X+ is 1.50Ý10?3M ? The pKa of acetic acid is 4.76.

Explanation / Answer

XCH3C00 ---- > X+ + CH3C00-

Ksp= ( X+ ) ( CH3C00-)

(X+) = 1.5 x 10-3 M

(CH3C00-) = Ksp/(X+)

= 9.1 x 10-6 /1.5 x 10-3

= 6.06 x 10-3 M

pH = pKa + log ( CH3C00-) /(CH3C00H)

pKa =4.76

So pH = 4.76 + log 6.06 x 10-3 /1

= 4.76 -2.217

pH= 2.5429

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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