Acid-Base Matching Worksheet - WordMint - Free Printable

Problem: Acid-Base Matching

The task is to match the questions on the left with the correct answers on the right. Below is the solution with explanations for each question.

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#### 1. Why is ammonia not considered a base under the Arrhenius definition?
- Answer: B. It is neutral
- Explanation: The Arrhenius definition of a base states that a base produces hydroxide ions (\( \text{OH}^- \)) in water. Ammonia (\( \text{NH}_3 \)) does not directly produce \( \text{OH}^- \) ions when dissolved in water. Instead, it reacts with water to form ammonium ions (\( \text{NH}_4^+ \)) and hydroxide ions (\( \text{OH}^- \)). Therefore, ammonia itself is not considered a base under the strict Arrhenius definition but rather a weak base in the Brønsted-Lowry sense.

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#### 2. What is acidic hydrogen?
- Answer: M. Hydrogen that produce + ions
- Explanation: Acidic hydrogen refers to a hydrogen atom in a molecule that can donate a proton (\( \text{H}^+ \)) to another substance. This is characteristic of acids, which dissociate in water to release \( \text{H}^+ \) ions.

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#### 3. Why are strong acids and bases good electrolytes?
- Answer: N. They completely dissociate
- Explanation: Strong acids and bases are good electrolytes because they completely dissociate in water, releasing their ions into the solution. For example, hydrochloric acid (\( \text{HCl} \)) dissociates completely into \( \text{H}^+ \) and \( \text{Cl}^- \), making it a strong electrolyte.

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#### 4. What kind of salt is produced when a strong acid and base react?
- Answer: A. Neutral Salt
- Explanation: When a strong acid (e.g., \( \text{HCl} \)) reacts with a strong base (e.g., \( \text{NaOH} \)), they neutralize each other to form a neutral salt (e.g., \( \text{NaCl} \)) and water. The resulting salt does not have acidic or basic properties.

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#### 5. What type of salt is made when a weak base or acid reacts with a strong base or acid?
- Answer: J. Acidic/ Basic salt
- Explanation: When a weak acid reacts with a strong base, the resulting salt is basic (e.g., \( \text{CH}_3\text{COONa} \) from acetic acid and sodium hydroxide). Similarly, when a weak base reacts with a strong acid, the resulting salt is acidic (e.g., \( \text{NH}_4\text{Cl} \) from ammonia and hydrochloric acid).

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#### 6. Why do people use antacid?
- Answer: C. To neutralize stomach acids
- Explanation: Antacids are used to neutralize excess stomach acid, which can cause discomfort or damage to the stomach lining. They typically contain bases like aluminum hydroxide or magnesium hydroxide, which react with stomach acid to reduce its acidity.

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#### 7. Why does a small change in pH mean a big change in acidity?
- Answer: G. Because pH is in logs
- Explanation: The pH scale is logarithmic, meaning a change of one pH unit represents a tenfold change in the concentration of \( \text{H}^+ \) ions. For example, a pH of 3 is ten times more acidic than a pH of 4.

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#### 8. What is the Arrhenius definition of a base?
- Answer: F. Dissociates to hydroxide ions
- Explanation: According to the Arrhenius definition, a base is a substance that dissociates in water to produce hydroxide ions (\( \text{OH}^- \)). Examples include sodium hydroxide (\( \text{NaOH} \)) and potassium hydroxide (\( \text{KOH} \)).

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#### 9. What is an Arrhenius acid?
- Answer: I. Dissociates to Hydrogen ions
- Explanation: An Arrhenius acid is a substance that dissociates in water to produce hydrogen ions (\( \text{H}^+ \)). Examples include hydrochloric acid (\( \text{HCl} \)) and sulfuric acid (\( \text{H}_2\text{SO}_4 \)).

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#### 10. Water has a pH of 7. What does this mean?
- Answer: B. It is neutral
- Explanation: A pH of 7 indicates that the concentration of \( \text{H}^+ \) ions is equal to the concentration of \( \text{OH}^- \) ions in the solution. This is the definition of a neutral solution, and pure water at 25°C has a pH of 7.

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#### 11. The pH scale increases from 1-14. Which represents acids?
- Answer: E. 1-7
- Explanation: On the pH scale, values below 7 represent acidic solutions, values above 7 represent basic solutions, and a value of 7 represents a neutral solution. Therefore, the range 1-7 corresponds to acids.

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#### 12. A very strong base turns litmus paper
- Answer: D. Blue
- Explanation: Litmus paper is a common indicator used to test the acidity or basicity of a solution. A strong base turns red litmus paper blue, indicating the presence of hydroxide ions.

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#### 13. What has a low \( K_b \) value?
- Answer: K. Acids
- Explanation: \( K_b \) (base dissociation constant) is a measure of the strength of a base. A low \( K_b \) value indicates a weak base. Conversely, a high \( K_b \) value indicates a strong base. Since acids are not described by \( K_b \), this question is somewhat ambiguous, but the closest match is "Acids," as acids are not bases.

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#### 14. What has a low \( K_a \) value?
- Answer: H. Bases
- Explanation: \( K_a \) (acid dissociation constant) is a measure of the strength of an acid. A low \( K_a \) value indicates a weak acid. Conversely, a high \( K_a \) value indicates a strong acid. Since bases are not described by \( K_a \), the closest match is "Bases," as bases are not acids.

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Final Answer:

\[
\boxed{
\begin{array}{ll}
1. & \text{B} \\
2. & \text{M} \\
3. & \text{N} \\
4. & \text{A} \\
5. & \text{J} \\
6. & \text{C} \\
7. & \text{G} \\
8. & \text{F} \\
9. & \text{I} \\
10. & \text{B} \\
11. & \text{E} \\
12. & \text{D} \\
13. & \text{K} \\
14. & \text{H} \\
\end{array}
}
\]