In everyday acid–base chemistry, which statement correctly describes acetic acid, the acid found in vinegar?

Introduction / Context:
This question links basic acid–base theory with the familiar household substance vinegar. Vinegar is essentially a dilute solution of acetic acid in water. In introductory chemistry and general science, students learn characteristic properties of acids and bases, such as taste, feel, reactions with metals, and the ions they release in water. The question asks you to identify which of the given statements correctly describes the behaviour of acetic acid, helping you distinguish acid properties from base properties and connect theory with a common kitchen example.

Given Data / Assumptions:
- The acid under discussion is acetic acid, CH3COOH, present in vinegar.
- Four descriptive statements are given, relating to feel, reaction with magnesium, taste, and ions released in solution.
- You are expected to know general properties of acids and bases in aqueous solutions.
- The context is qualitative behaviour, not exact numerical values like pH.

Concept / Approach:
Acids are substances that, in aqueous solution, donate hydrogen ions (H+), while bases accept H+ or release hydroxide ions (OH-). Acids typically have a sour taste and react with active metals such as magnesium, zinc, or iron to produce hydrogen gas. Bases often feel slippery or soapy on the skin, taste bitter, and release OH- ions in water. Acetic acid is a weak acid, but it still shows typical acid behaviour, including reacting with magnesium metal to give a salt (magnesium acetate) and hydrogen gas. Therefore, the correct statement is the one describing its reaction with magnesium producing H2 gas.

Step-by-Step Solution:
Step 1: Recall that acetic acid is an acid, not a base, and is responsible for the sour taste of vinegar. Step 2: Remember that acids react with active metals like magnesium to form a salt and release hydrogen gas. Step 3: Examine option B, which states that acetic acid reacts with magnesium to produce hydrogen gas. This matches the typical acid–metal reaction pattern. Step 4: Recognise that slippery feel and bitter taste are characteristic of bases, not acids. Step 5: Recall that releasing OH- ions in solution is a property of bases (like NaOH), whereas acids release H+ or form hydronium ions. Step 6: Conclude that the only statement correctly describing acetic acid in vinegar is that it reacts with magnesium to produce hydrogen gas, so option B is correct.

Verification / Alternative check:
You can verify this behaviour with the general reaction form for acids and metals: acid + metal gives salt + hydrogen gas. For acetic acid and magnesium, the reaction can be written as 2CH3COOH + Mg gives (CH3COO)2Mg + H2. This confirms that hydrogen gas is evolved when magnesium reacts with acetic acid. In contrast, bases are commonly associated with reactions that neutralise acids and produce water and salt, and they contain OH- ions as the principal anion in solution. Experimental observations from a basic school laboratory also show that acids are sour and that bases feel slippery and taste bitter (though tasting chemicals is not recommended for safety reasons).

Why Other Options Are Wrong:
The statement that acetic acid feels slippery is wrong because slippery feel is a characteristic property of bases such as soap solutions and sodium hydroxide. Saying it tastes bitter is incorrect because acids are typically sour, not bitter; bitterness is commonly associated with many basic substances. The statement that acetic acid releases OH- in solution is fundamentally wrong because acids release H+ ions, while OH- ions are characteristic of bases. Hence, options A, C, and D do not correctly describe acetic acid in vinegar.

Common Pitfalls:
Students sometimes mix up the properties of acids and bases, especially when trying to remember taste and feel, and may incorrectly associate slippery or bitter sensations with acids. Another mistake is to think that any substance that reacts with metals must be a strong acid, forgetting that even weak acids like acetic acid can react with active metals. Some may also focus only on the taste property and overlook reactivity with metals. To avoid these errors, keep a clear mental table: acids are sour, produce H+ in water, and react with metals to release hydrogen; bases are bitter, feel slippery, and release OH- ions in solution.

Final Answer:
The correct description is that acetic acid reacts with magnesium metal to produce hydrogen gas (H2).