Problem 40 - Chemistry Matter and Change

Question

Boiling Water At what temperature would 250 \(\mathrm{mL}\) of water boil? 1000 \(\mathrm{mL}\) ? Is the boiling point an intensive or extensive property? Explain.

Step-by-Step Solution

Answer

The boiling point is 100°C for both 250 mL and 1000 mL of water, and it is an intensive property.

Step 1: Understanding Intensive vs. Extensive Properties

Intensive properties are independent of the amount of substance present, while extensive properties depend on the quantity. Examples of intensive properties include boiling point, density, and color. Volume and mass, on the other hand, are examples of extensive properties.

Step 2: Identifying the Boiling Point of Water

The boiling point of water is a specific temperature at which water turns into vapor. At sea level and under standard atmospheric pressure, the boiling point of water is 100°C or 212°F. This temperature does not change based on the amount of water present.

Step 3: Applying the Boiling Point to Different Volumes

Since the boiling point is an intensive property, the volume of water does not affect it. Therefore, 250 mL of water boils at the same temperature as 1000 mL of water. Both will boil at 100°C under standard atmospheric pressure.

Key Concepts

Boiling Point

The "boiling point" of a substance is defined as the temperature at which it transitions from a liquid to a gas. For water, this crucial transformation happens at 100°C (212°F) when at sea level, under standard atmospheric pressure. This means that no matter how much water you have, be it just a cup or an entire pot, it will always begin to boil at the same temperature if these conditions remain constant.
Boiling point is an example of an intensive property. Intensive properties are characteristics of a substance that do not change, regardless of how much you have. Whether you are boiling 250 mL or 1000 mL of water, the boiling point remains steady at 100°C. This is because the boiling point is not affected by the amount of water, but rather by external conditions like atmospheric pressure.

Extensive Properties

When we talk about properties that change with the amount of substance, we are referring to "extensive properties." These are properties that depend directly on the substance's size or quantity.
Some common examples of extensive properties include:

• Volume: The space a substance occupies.
• Mass: The amount of matter in a substance.

These properties are different from intensive properties because if you have more or less of the substance, these properties will change. For instance, if you have more water, the mass and volume will increase proportionally. However, unlike temperature or boiling point, the mass and volume scale with the quantity of the object or material that you have on hand.

Volume and Mass

Volume and mass are fundamental attributes of matter, considered extensive properties. Let's delve into each:

Volume
If you have more of a liquid, like water, you have more volume. Volume tells us how much space a liquid, solid, or gas occupies. For example, a glass filled with 250 mL of water takes up less space than a bottle holding 1000 mL. As the quantity of water increases, so does its volume.

Mass
Mass measures the total amount of matter in an object. It is linked directly to the substance present. Imagine carrying a small bottle versus a large jug of water. The larger jug would be heavier because the mass corresponds to the specific amount of water it contains. The more water there is, the greater the mass.
Both volume and mass are important in understanding how extensive properties vary with the amount of material present, offering a contrast to intensive properties like the boiling point.