Ch.16 - Aqueous Equilibrium WorksheetSee all chapters
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Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds

Solution: A 0.70 g sample of a weak monoprotic acid was dissolved in 150 mL of water and titrated with a 0.055 M solution of KOH at 25°C. At the half-equivalence point, after addition of 25.5 mL of the KOH solu

Problem

A 0.70 g sample of a weak monoprotic acid was dissolved in 150 mL of water and titrated with a 0.055 M solution of KOH at 25°C. At the half-equivalence point, after addition of 25.5 mL of the KOH solution, the pH was 3.8.

What will the pH be at the equivalence point of the above titration?

A. 7.60

B. 6.03

C. 7.97

D.  2.83

E. 11.17

Solution

We are being asked to calculate the pH at the equivalence point for titration of a weak monoprotic acid (HA) with a 0.055 M solution of KOH.


We will calculate the pH of the solution at the equivalence point using the following steps:

Step 1. Write the chemical equation for the reaction between HA and KOH.
Step 2. Calculate the initial amounts of HA and KOH in moles before the reaction happens.
Step 3. Construct an ICF Chart.
Step 4. Calculate the new concentration of the species left in the solution.
Step 5. Calculate pH.


Step 1. Write the chemical equation for the reaction between HA and KOH.

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