Problem 18 - Chemistry: The Central Science in SI Units, Global Edition

Question

Zirconia, an oxide of zirconium, is often used as an affordable diamond substitute. Just like diamond, it is a colorless crystal which sparkles under sunlight. Which of the following physical properties do you think would help in differentiating between diamond and Zirconia-melting point, density, or physical state?

Step-by-Step Solution

Answer

Both the melting point and density can be used to differentiate between diamond and Zirconia. Diamond has a melting point of about 3820 K, higher than Zirconia's melting point which is around 2680 K. On the other hand, diamond has a lower density, 3.51 g/cm³, compared to Zirconia which ranges from 5.6 to 6.0 g/cm³. Their physical state, both being solid crystals, however, is not a distinguishing property.

Step 1: Gathering information about diamond and Zirconia properties

Before we can determine which property will help us differentiate between diamond and Zirconia, we need to know their values for each property. For diamond: - Melting point: about 3820 Kelvin (K) - Density: 3.51 grams per cubic centimeter (g/cm³) - Physical state: Solid crystal For Zirconia: - Melting point: about 2680 Kelvin (K) - Density: 5.6 - 6.0 grams per cubic centimeter (g/cm³) - Physical state: Solid crystal Now that we have the values for each property, we can compare them and decide which one is most helpful in distinguishing diamond from Zirconia.

Step 2: Comparing physical states

Both diamond and Zirconia are solid crystals. This property is not useful in differentiating between the two materials since they have the same physical state.

Step 3: Comparing melting points

The melting point of diamond is about 3820 K, while that of Zirconia is around 2680 K. The melting points are quite different, so this property can be helpful in distinguishing between the two materials.

Step 4: Comparing densities

The density of diamond is 3.51 g/cm³, whereas the density of Zirconia ranges from 5.6 to 6.0 g/cm³. The densities are also quite different, so this property can be helpful in distinguishing between the two materials.

Step 5: Conclusion

In distinguishing between diamond and Zirconia, both the melting point and density are helpful properties, whereas the physical state is not. The melting point and density of diamond and Zirconia are substantially different, making it easier to differentiate between the two materials using these properties.

Key Concepts

Melting Point

The melting point is the temperature at which a solid transitions into a liquid. It is an essential physical property that can help identify or differentiate between substances. For example, in the case of diamond and zirconia, their melting points are quite different.
Zirconia has a melting point of about 2680 Kelvin, while diamond's melting point is significantly higher at approximately 3820 Kelvin. This difference is due to the strong covalent bonds between carbon atoms in diamond. Such a high melting point indicates exceptional thermal stability, meaning diamond can withstand more heat without changing its state.
Higher melting point means greater resistance to heat before molecular structure changes. This property is useful when selecting materials for heat-resistant applications.

• The melting point can help in identifying substances that look similar but have different uses.
• It's indicative of the strength of bonds within a material, highlighting differences between compounds like diamond and zirconia.

Checking the melting point is crucial in material science and engineering, especially when authenticating substances, as it provides clear evidence of a material’s identity through its unique thermal behavior.

Density

Density is the measure of mass per unit volume and is expressed in grams per cubic centimeter (g/cm³). It is a fundamental physical property used to differentiate between materials, as it indicates how compact or spread out the matter in a substance is. Density is particularly useful in distinguishing substances that may appear similar physically but are fundamentally different.
For diamond and zirconia:

• Diamond has a density of about 3.51 g/cm³.
• Zirconia's density ranges between 5.6 and 6.0 g/cm³.

This noticeable difference helps differentiate between the two materials. Zirconia is denser, meaning it has more mass in the same volume compared to diamond.
In practical terms, this means that for pieces of zirconia and diamond of the same size, zirconia will feel heavier. This property not only assists in identification but can also influence how materials behave under different forces or in various applications.
For students and professionals alike, considering density is crucial when dealing with multipurpose materials that may look identical visually but perform very differently in practical applications.

Physical State

Physical state refers to the distinct forms that different phases of matter take on. Common states include solid, liquid, and gas. Both diamond and zirconia are found in a solid crystal form, which makes this property less helpful in differentiating between the two.
While the physical state provides basic information about a material, it doesn’t offer the specificity needed to distinguish between substances with many similar characteristics, like diamond and zirconia. Both of these materials are solid crystals, which are characterized by a structured pattern and high rigidity.
It's crucial to understand that physical state, though insightful for broad categorization, falls short when it comes to substances that require more precise identification methods. For purposes where exact material identification is necessary, properties like melting point and density become more relevant and effective for differentiation.
Thus, while solid state provides general context, it's primarily other measures such as density and melting point that offer definitive clues to help distinguish similar-appearing materials.