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 9.20×106.

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 1.50×103M ? The pKa of acetic acid is 4.76.

It's not 2.21

Explanation / Answer

Answer:

Given Ksp = 9.20*10-6

Given [X+] = 1.05*10-3

So that [CH3COO-] = 1.05*10-3

pH = pKa + log[X+][CH3COO-]/[XCH3COO]

= 4.76 + log [1.05*10-3]1.05*10-3]/[9.20*10-6]

=4.76+log[0.11]

=4.76-0.920

pH=3.83

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