Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH₃COOH) is added to test tube B. Amount and concentration taken for both the acids are same. In which test tube will the fizzing occur more vigorously and why?
Fizzing will occur more vigorously in test tube A containing hydrochloric acid (HCl).
HCl is a strong acid that completely ionizes in water to produce a high concentration of hydrogen ions (H⁺). Acetic acid (CH₃COOH) is a weak acid that only partially ionizes in water, producing fewer hydrogen ions at the same concentration.
When magnesium reacts with acids, hydrogen gas is produced which causes the fizzing. Since test tube A has more hydrogen ions available due to complete ionization of HCl, the reaction with magnesium is more vigorous, producing hydrogen gas more rapidly and causing more intense fizzing.
Explanation
This textbook question tests understanding of strong versus weak acids. The context establishes that acids generate hydrogen gas on reacting with metals (Section 2.2). The key concept is that HCl completely dissociates in water producing maximum H⁺ ions, while acetic acid only partially dissociates. More H⁺ ions available means a faster and more vigorous reaction with the magnesium ribbon, resulting in more intense fizzing in test tube A.
Solution Steps
Step 1: Identify that HCl is a strong acid and acetic acid is a weak acid
Step 2: Understand that strong acids completely ionize producing more H⁺ ions at same concentration
Step 3: Relate higher H⁺ ion concentration to more vigorous reaction with magnesium
Step 4: Conclude that test tube A will show more vigorous fizzing due to greater hydrogen gas production