Which acid is injected into the skin when a common ant bites a person and causes a burning sensation?

Introduction / Context:
Many everyday experiences, such as insect bites and stings, are linked to simple chemistry concepts. The burning sensation from an ant bite is caused by a specific acid injected into the skin. Identifying this acid is a common general science question that reinforces the connection between daily life and basic chemistry. It also helps students remember the names and simple uses of familiar acids.

Given Data / Assumptions:

• The situation described is an ant bite on human skin.
• The options include hydrochloric acid, formic acid, acetic acid, and phosphoric acid.
• We assume the common household or garden ant, not exotic species with different venoms.

Concept / Approach:
The name formic acid actually comes from the Latin word for ant, formica, because this acid was first isolated from ants. Many ants inject or spray formic acid as a defense mechanism. When an ant bites, this acid causes irritation, pain, and a mild burning feeling on the skin. Hydrochloric acid is found in stomach gastric juice, acetic acid is the main component of vinegar, and phosphoric acid is used in fertilizers and some soft drinks, but they are not the acids injected by ants.

Step-by-Step Solution:
1. Recall that formic acid was historically obtained from distilling ants and is closely associated with them in chemical history.2. Understand that many ant species use formic acid as a chemical weapon to defend themselves and attack prey.3. When an ant bites or stings, the small amount of formic acid it injects or sprays causes a sharp, burning sensation and redness on the skin.4. Hydrochloric acid, while strong, is primarily inside the human stomach and is not associated with ant bites.5. Acetic acid is present in vinegar and is used in foods and cleaning products, not in ant venom.6. Phosphoric acid is used industrially and in some beverages, again with no direct link to ant bites.7. Therefore, the acid released when an ant bites is formic acid.

Verification / Alternative check:
Chemistry textbooks and general science references frequently mention that the pain from an ant bite is due to formic acid. Some experiments show that neutralising the area with a mild base can reduce the burning sensation, which supports the idea that an acid is involved. Historical notes about the origin of the term formic acid confirm its connection to ants, strengthening the association between this acid and ant bites.

Why Other Options Are Wrong:
Option A, hydrochloric acid, is incorrect because it is produced in the human stomach and used in laboratories, not in ants. Option C, acetic acid, is the acid in vinegar and is not used by ants as a venom. Option D, phosphoric acid, has industrial and food uses but is not related to ant bites. None of these three acids have a biological link to the behaviour of common ants.

Common Pitfalls:
Students sometimes guess hydrochloric acid because they know it is a strong acid from the stomach, or acetic acid because it is familiar from vinegar. However, the keyword ant should lead directly to formic acid. Remembering the origin of the name formic and linking it with ants is a simple way to avoid confusion and quickly pick the correct answer in such questions.

Final Answer:
The acid released when a common ant bites a person is formic acid.