In what range of temperature is the expansion of water anomalous?

Analysis of the Question

The question asks for the specific temperature range where water behaves differently from most other substances regarding its volume and density as it is heated or cooled.

Concept Explanation: Anomalous Expansion of Water

Most substances expand when heated and contract when cooled. However, water exhibits a unique behavior known as anomalous expansion.

1. Normal behavior: As you cool most liquids, they contract (volume decreases) and their density increases.
2. Water's behavior: When water is cooled from a higher temperature down to $4^\circ\text{C}$, it contracts as expected. However, as it is cooled further from $4^\circ\text{C}$ down to $0^\circ\text{C}$, it begins to expand instead of contracting.
3. Density implication: Because volume increases as water cools from $4^\circ\text{C}$ to $0^\circ\text{C}$, its density decreases. This is why ice floats on water—it is less dense than liquid water at $4^\circ\text{C}$.

Step-by-Step Solution

• Step 1: Identify the temperature at which water reaches its maximum density. This is $4^\circ\text{C}$.
• Step 2: Observe the behavior between $0^\circ\text{C}$ and $4^\circ\text{C}$. In this range, as temperature increases, the volume of water decreases (it contracts). As temperature decreases, the volume increases (it expands).
• Step 3: Compare this with the provided options. The range where this "abnormal" or "anomalous" behavior occurs is between $0^\circ\text{C}$ and $4^\circ\text{C}$.

Conclusion

Exam Tip

Remember the "4-degree rule": Water is densest at $4^\circ\text{C}$. Anything below that temperature (down to $0^\circ\text{C}$) causes water to expand, which is why water pipes often burst in very cold climates—the water expands as it turns to ice!