Question

The Ka value for acetic acid, CH3COOH(aq), is 1.8x10^-5. Calculate the ph of a 2.80 M acetic acid solution.

PH=

Calculate the ph of the resulting solution when 3.00 mL of the 2.80 M acetic acid is diluted to make a 250.0 mL solution.

PH=

Answers are not 4.6 or 3.8

Answer 1

Concepts and reason

Power of hydrogen ions (pH)

The pH is defined as the negative logarithmic function of the concentration of hydrogen () ion in an aqueous solution.

Molar concentration:

The molar concentration is the number of moles of a solute that will dissolve in a liter of solution. It is expressed as mol/L or M (molarity).

Fundamentals

Molar concentration:

Dilution equation:

Acid dissociation constant:

Equation for the pH of the solution:

Henderson–Hasseslbalch Equation:

An ICE table is used to find the concentrations or moles of individual reactants or products at equilibrium.

The expansion of an ICE table is as follows:

All quantities are expressed in terms of concentrations or moles.

(1)

Given data:

Initial concentration of acetic acid, = 2.80 M

At equilibrium: The change in concentration is x.

(2)

Given:

Concentration of acetic acid, = 0.0336 M

At equilibrium: The change in concentration is x.

Ans: Part 1

The pH of a 2.80 M acetic acid solution is

Part 2

The pH of the resulting solution is