- Analyze the reaction as a neutralization between a base (NaOH) and an acid (X) to form a salt (NaCH3COO) and water (H2O).
- Identify that the acetate ion (CH3COO-) and the hydrogen ion (H+) combine to form the acid reactant.
- Deduce the reactant X as acetic acid, represented by the chemical formula CH3COOH.
- The correct choice is \(\boxed{\text{CH}_3\text{COOH}}\).
Explanation
- Analysis of the Reaction Type
The given chemical equation is a classic neutralization reaction, which typically follows the general form: \[ \text{Base} + \text{Acid} \longrightarrow \text{Salt} + \text{Water} \] Specifically, we are given: \[ \text{NaOH} + X \longrightarrow \text{NaCH}_3\text{COO} + \text{H}_2\text{O} \] In this reaction, sodium hydroxide (NaOH) is a strong base that dissociates into sodium ions (\(\text{Na}^+\)) and hydroxide ions (\(\text{OH}^-\)). The products formed are water (\(\text{H}_2\text{O}\)) and sodium acetate (\(\text{NaCH}_3\text{COO}\)). For water to form, the hydroxide ion (\(\text{OH}^-\)) from the base must react with a hydrogen ion (\(\text{H}^+\)) from the acid \(X\). Consequently, the remaining component of the acid must be the acetate anion (\(\text{CH}_3\text{COO}^-\)) to form the sodium acetate salt.
- Deducing the Chemical Formula of X
To identify the missing reactant \(X\), we observe that the salt product \(\text{NaCH}_3\text{COO}\) is composed of a sodium cation (\(\text{Na}^+\)) and an acetate anion (\(\text{CH}_3\text{COO}^-\)). Since the sodium ion originates from the base \(\text{NaOH}\), the acetate ion must have originated from the acid \(X\). When we combine the necessary hydrogen ion (\(\text{H}^+\)) from the acid with the acetate anion (\(\text{CH}_3\text{COO}^-\)), we obtain: \[ \text{H}^+ + \text{CH}_3\text{COO}^- \longrightarrow \text{CH}_3\text{COOH} \] Thus, the acid reactant \(X\) is acetic acid, which is represented by the formula \(\text{CH}_3\text{COOH}\). Checking the provided choices, this corresponds directly to the last option provided.
- Verification and Conclusion
The reaction is balanced as: \(\text{NaOH} + \text{CH}_3\text{COOH} \longrightarrow \text{NaCH}_3\text{COO} + \text{H}_2\text{O}\). Each element is balanced on both sides of the equation, confirming our identification of \(X\) as \(\text{CH}_3\text{COOH}\). The final answer is \(\boxed{\text{CH}_3\text{COOH}}\).
Examples
Understanding acid-base neutralization is vital in fields like environmental science and food chemistry. For example, when you have an upset stomach caused by excess stomach acid (\(\text{HCl}\)), you might take an antacid like sodium bicarbonate (\(\text{NaHCO}_3\)). This is a neutralization reaction: \(\text{NaHCO}_3 + \text{HCl} \longrightarrow \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2\). Just as we identified the acid \(\text{CH}_3\text{COOH}\) to neutralize \(\text{NaOH}\), chemists use these principles to neutralize industrial wastewater, manage soil pH for better crop growth, or formulate medicines. Mastering these reactions allows us to control and predict chemical environments efficiently.