Two 25.0-mL samples, one 0.100 M HCl and the other 0.100 M HF, are titrated with 0.200 M KOH. c. Which titration curve has the lower initial pH?

Verified step by step guidance

Step 1: Understand the nature of the acids involved. HCl is a strong acid, while HF is a weak acid.

Step 2: Recall that the initial pH of a solution is determined by the concentration and strength of the acid.

Step 3: For strong acids like HCl, they dissociate completely in water, leading to a higher concentration of H+ ions compared to weak acids like HF, which only partially dissociate.

Step 4: Calculate the initial pH for each solution. For HCl, use the formula pH = -\(\log\)[H^+], where [H^+] is the concentration of HCl. For HF, consider the acid dissociation constant (Ka) to find [H^+].

Step 5: Compare the initial pH values calculated for HCl and HF. The solution with the higher concentration of H+ ions (lower pH) will be the one with the strong acid, HCl.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Strong vs. Weak Acids

Strong acids, like HCl, completely dissociate in solution, resulting in a higher concentration of hydrogen ions (H+) and a lower initial pH. In contrast, weak acids, such as HF, only partially dissociate, leading to a higher initial pH due to a lower concentration of H+ ions in solution.

Titration Curves

A titration curve plots pH against the volume of titrant added. The shape of the curve is influenced by the strength of the acid and base involved. For strong acid-strong base titrations, the initial pH is low, while weak acid-strong base titrations show a more gradual increase in pH, reflecting the acid's partial dissociation.

pH Scale

The pH scale measures the acidity or basicity of a solution, ranging from 0 (very acidic) to 14 (very basic), with 7 being neutral. The pH is logarithmically related to the concentration of H+ ions; thus, a small change in pH corresponds to a significant change in H+ concentration, which is crucial for understanding the initial conditions of the titration.

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Related Practice

Textbook Question

Two 20.0-mL samples, one 0.200 M KOH and the other 0.200 M CH₃NH₂, are titrated with 0.100 M HI. b. Is the pH at the equivalence point for each titration acidic, basic, or neutral?

Textbook Question

Two 20.0-mL samples, one 0.200 M KOH and the other 0.200 M CH₃NH₂, are titrated with 0.100 M HI. a. What is the volume of added acid at the equivalence point for each titration?

Textbook Question

The graphs labeled (a) and (b) show the titration curves for two equal-volume samples of monoprotic acids, one weak and one strong. Both titrations were carried out with the same concentration of strong base.

(ii) Which graph corresponds to the titration of the strong acid and which one to the titration of the weak acid?

Textbook Question

Two 25.0-mL samples, one 0.100 M HCl and the other 0.100 M HF, are titrated with 0.200 M KOH. b. Is the pH at the equivalence point for each titration acidic, basic, or neutral?

Textbook Question

Two 25.0-mL samples, one 0.100 M HCl and the other 0.100 M HF, are titrated with 0.200 M KOH.

d. Sketch each titration curve.