Question

What is the ratio of [A−]/[HA][A−]/[HA] at pH 5.75?5.75? The pKpK of formic acid is 3.75. [A−][HA]=[A−][HA]= Draw the structure of HAHA for formic acid. Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase C O H Draw the structure of the conjugate base for formic acid. Select Draw Rings More Erase Select Draw Rings More Erase Select Draw Rings More Erase C O H What is the fractional charge on the acid at the given pH?

Answer 1

The ratio of [A⁻] / [HA] is 100

Step-by-step explanation:

The structure of the formic acid (Weak acid), is in the picture.

Using H-H equation, we can determine the ratio of [A⁻] / [HA] for a weak acid as Formic Acid:

pH = pKa + log₁₀ [A⁻] / [HA]

Where A⁻ is the conjugate base of the weak acid, HA.

Solving for formic acid at pH = 5.75:

5.75 = 3.75 + log₁₀ [A⁻] / [HA]

2 = log₁₀ [A⁻] / [HA]

10^2 = [A⁻] / [HA]

The ratio of [A⁻] / [HA] is 100