Question

How could you tell experimentally if \(\operatorname{Ti} \mathrm{O}_{2}\) is an ionic solid or a network solid?

Short answer

To determine experimentally if TiO2 is an ionic solid or a network solid, perform the following tests: 1. Measure the melting point of TiO2. If it is very high, it may indicate a network solid. 2. Attempt to dissolve TiO2 in water. If it dissolves, this suggests an ionic solid; if insoluble, it suggests a network solid. 3. Test the electrical conductivity of dissolved or molten TiO2. Conductivity would indicate an ionic solid, while poor conductivity suggests a network solid. Analyze the results, comparing them to characteristic properties of ionic and network solids, to classify TiO2 based on these experimental observations.

Step-by-step solution

Check the melting point of TiO2

Measure the melting point of titanium dioxide (TiO2) using a high-temperature furnace or another suitable method. The melting point of ionic solids is typically high, while network solids have very high melting points.

Dissolve TiO2 in water

Try to dissolve a small amount of TiO2 in water. Observe and record whether the solid dissolves or remains insoluble. Ionic solids usually dissolve in water, whereas network solids are typically insoluble in water.

Conductivity test

If TiO2 dissolves in water, test the resulting solution for electrical conductivity using a conductivity meter. If TiO2 does not dissolve in water, melt a small amount of the solid and test its electrical conductivity when molten. Ionic solids usually conduct electricity when dissolved or molten, whereas network solids are poor conductors of electricity.

Analyze the results

Compare the results from the melting point, solubility, and conductivity tests to the characteristic properties of ionic and network solids. If TiO2 has a high (but not very high) melting point, dissolves in water, and conducts electricity when dissolved or molten, it is likely to be an ionic solid. If TiO2 has a very high melting point, is insoluble in water, and does not conduct electricity, it is more likely to be a network solid.

Key concepts

Melting Point of Solids

Understanding how high solids can withstand temperature before they change into a liquid is crucial in identifying their types. The melting point is an essential concept in classifying solids.
In general, ionic solids and network solids both exhibit high melting points because of the strong forces that hold their particles together. However, network solids such as diamond often have very high melting points compared to typical ionic compounds.
For example, titanium dioxide (\(\text{TiO}_2\)) will need to be observed regarding its melting behavior. If the melting point is extraordinarily high, it could suggest that \(\text{TiO}_2\) is a network solid rather than an ionic solid.
These properties result from strong covalent bonds in network solids, as opposed to the electrostatic forces in ionic solids. Hence, measuring the melting point helps differentiate between the two solid types.

Solubility Testing

Solubility testing involves determining whether a substance can dissolve in water or another solvent. This test provides significant insights into the nature of a solid.
Typically, ionic solids dissolve in water because the ions dissociate in the solvent, leading to a conducting solution. Conversely, network solids do not dissolve due to their extensive covalent bond structure, which does not break apart easily in solvents like water.
To experiment with \(\text{TiO}_2\), try dissolving it in water and observing if it forms a solution. If it does, this indicates ionic characteristics. If it remains insoluble, it points more towards a network solid.
While solubility is a helpful property to test, it's important to remember that some ionic solids may have low solubility and might not dissolve entirely, which could lead to some ambiguity.

Electrical Conductivity of Solids

Electrical conductivity tests how well a substance can carry an electric current. This is another key experiment to distinguish ionic solids from network solids.
When ionic solids dissolve in water, they release ions that freely move in the solution. This allows the solution to conduct electricity. Additionally, when an ionic solid is molten, it will conduct electricity due to free-moving ions.
Network solids like diamond do not conduct electricity in either solid or dissolved state because their electrons are fixed within their covalent bonds and cannot move freely.
For \(\text{TiO}_2\), test its conductivity both when it is dissolved in water and when it is in its molten state. If it conducts electricity, it is likely ionic. If not, it might be a network solid.
Conductivity tests provide valuable data that complements findings from the melting point and solubility tests, aiding in determining the solid's nature.