Problem 37 - Chemistry and Chemical Reactivity

Question

Carbon tetrachloride, \(\mathrm{CCl}_{4}\), a common liquid compound, has a density of \(1.58 \mathrm{g} / \mathrm{cm}^{3} .\) If you place a piece of a plastic soda bottle \(\left(d=1.37 \mathrm{g} / \mathrm{cm}^{3}\right)\) and a piece of aluminum \(\left(d=2.70 \mathrm{g} / \mathrm{cm}^{3}\right)\) in liquid \(\mathrm{CCl}_{4},\) will the plastic and aluminum float or sink?

Step-by-Step Solution

Answer

The plastic floats, and the aluminum sinks.

Step 1: Understand Density Basics

The density of a substance determines whether it will float or sink when placed in a liquid. A substance will float if its density is less than the liquid's density, and it will sink if its density is greater.

Step 2: Compare Plastic Density to CCl4

The density of the plastic is given as 1.37 g/cm³. The density of CCl₄ is given as 1.58 g/cm³. Since the density of the plastic is less than the density of CCl₄, the plastic will float.

Step 3: Compare Aluminum Density to CCl4

The density of the aluminum is given as 2.70 g/cm³. The density of CCl₄ is 1.58 g/cm³. Since the density of the aluminum is greater than the density of CCl₄, the aluminum will sink.

Key Concepts

Floatation

Floatation is a fascinating phenomenon that occurs when an object rests on the surface of a liquid instead of sinking. This happens because the liquid can support the weight of the object. The basic rule for floatation is tied to density – an object will float if its density is less than that of the liquid in which it is placed.

Let's consider a boat floating on water. The boat is made of materials that, when combined with the air inside it, make its overall density less than that of water. Thus, it floats. We can predict floatation by checking the densities as with the example of different materials in carbon tetrachloride (CCl₄). If you take a piece of plastic and a piece of aluminum, the plastic will float because it has a lower density compared to carbon tetrachloride, but the aluminum will sink as its density is higher.

In essence:

• Object floats if density < liquid's density
• Object sinks if density > liquid's density

Understanding floatation helps us design boats, ships, and even predict how objects will behave in liquids.

Material Properties

Material properties determine how substances behave in different environments. One of the most essential aspects of a material is its density, which affects whether it will float or sink in a liquid.

Density is the mass per unit volume of a substance, often expressed in grams per cubic centimeter (g/cm³). Materials like plastic bottles and aluminum have different densities affecting their buoyancy in liquids. For example, in carbon tetrachloride:

• Plastic density: 1.37 g/cm³
• Aluminum density: 2.70 g/cm³

The different densities reveal how materials will behave when submerged in other substances. Lower-density materials, such as many plastics, are more likely to float, while higher-density ones, like metals, tend to sink.

Understanding material properties is crucial not only in physics but also in industries like manufacturing, construction, and engineering.

Carbon Tetrachloride

Carbon tetrachloride, chemically represented as CCl₄, is a unique liquid with specific properties that affect how other substances interact with it. This compound has a high density of about 1.58 g/cm³, making it denser than many common materials, particularly organic compounds like plastics.

CCl₄ was widely used in the past for industrial purposes such as cleaning and degreasing due to its ability to dissolve oils. However, it is important to handle it with care, as it can be toxic and environmentally harmful.

When examining floatation related to CCl₄, you can determine which materials will float based on density comparisons. With its significant density, carbon tetrachloride provides an excellent medium for observing density-related phenomena, serving as a clear example of the principles of buoyancy.

Density Comparison

The concept of density comparison is fundamental to understand how different materials relate to one another in terms of buoyancy. By comparing the density of a solid to that of a liquid, we can predict their interaction, like in our example with carbon tetrachloride.

For effective comparison:

• Determine the density of the liquid (e.g., CCl₄ = 1.58 g/cm³).
• Compare it with the density of the material in question (e.g., Plastic = 1.37 g/cm³, Aluminum = 2.70 g/cm³).

The result of this comparison indicates whether the material floats (density less than the liquid) or sinks (density more than the liquid). In practice, this understanding allows us to predict and explain observations without having to test each possibility experimentally.

In science and engineering, these theories help guide the development of materials and products suitable for specific purposes, ensuring functionality and efficiency.