Define acid strength versus concentration and explain why pH depends on both.

Define acid strength versus concentration and explain why pH depends on both.

• A. Strength refers to the degree of dissociation; concentration is the amount present; pH depends on both.
• B. Strength refers to the amount of solute; concentration is the degree of dissociation; pH depends only on concentration.
• C. Strength is pH value; concentration is volume; pH depends on temperature.
• D. Strength and concentration are the same.

Answer: (A)

Acid strength is about how completely an acid donates protons in water, described by the dissociation constant. A strong acid dissociates nearly completely, while a weak acid only partially dissociates. Concentration is how much acid is present in the solution. pH depends on both because it reflects the hydrogen ion activity produced, which comes from how strong the acid is and how much of it there is. For a strong acid, [H+] is roughly equal to the concentration, so pH mainly tracks how much acid you added. For a weak acid, only a fraction dissociates, so [H+] depends on both Ka (strength) and C (concentration), with [H+] roughly proportional to the square root of Ka times C in typical cases. So the best description is that strength is the degree of dissociation and concentration is the amount present, and pH depends on both.

Acid strength is about how completely an acid donates protons in water, described by the dissociation constant. A strong acid dissociates nearly completely, while a weak acid only partially dissociates. Concentration is how much acid is present in the solution. pH depends on both because it reflects the hydrogen ion activity produced, which comes from how strong the acid is and how much of it there is. For a strong acid, [H+] is roughly equal to the concentration, so pH mainly tracks how much acid you added. For a weak acid, only a fraction dissociates, so [H+] depends on both Ka (strength) and C (concentration), with [H+] roughly proportional to the square root of Ka times C in typical cases. So the best description is that strength is the degree of dissociation and concentration is the amount present, and pH depends on both.