Question

Match the following physical and chemical properties with cyclohexane, \(\mathrm{C}_{6} \mathrm{H}_{12}\), or calcium nitrate, \(\mathrm{Ca}\left(\mathrm{NO}_{3}\right)_{2}\) : a. melts at \(500^{\circ} \mathrm{C}\) b. is insoluble in water c. does not burn in air d. is a liquid at room temperature

Short answer

a. Calcium nitrate, b. Cyclohexane, c. Calcium nitrate, d. Cyclohexane

Step-by-step solution

- Analyze Property 'a'

Consider the melting point of both substances. Calcium nitrate typically melts at a high temperature around 500°C. Cyclohexane, on the other hand, is not known for such a high melting point.

- Analyze Property 'b'

Check the solubility in water. Cyclohexane is a nonpolar hydrocarbon and is generally insoluble in water. Calcium nitrate, being an ionic compound, is highly soluble in water.

- Analyze Property 'c'

Examine flammability in air. Cyclohexane is a hydrocarbon and can burn in air. Calcium nitrate is not flammable and can actually act as an oxidizer.

- Analyze Property 'd'

Determine the state at room temperature. Cyclohexane is a liquid at room temperature, whereas calcium nitrate is a solid.

Key concepts

melting point

The melting point of a substance is the temperature at which it changes from a solid to a liquid. This temperature indicates how much energy is required to overcome the forces holding its particles in a solid structure.

Substances with high melting points, like calcium nitrate (around 500°C), have strong intermolecular or ionic bonds. Conversely, substances like cyclohexane, with lower melting points, have weaker intermolecular forces. Take note that understanding the melting point helps determine the thermal stability and practical applications of the substance.

For instance, calcium nitrate, with its high melting point, can withstand significant heat before melting, making it useful in high-temperature environments.

solubility

Solubility is the ability of a substance to dissolve in a solvent, like water. This property is crucial in understanding chemical behavior and practical uses. For example, calcium nitrate is highly soluble in water due to its ionic nature. Its ions can interact with water molecules easily.

On the other hand, cyclohexane is a nonpolar hydrocarbon and doesn't mix well with water. Nonpolar substances are generally insoluble in polar solvents like water. This fundamental principle helps predict how substances interact in different environments.

So, if you need a substance to dissolve in water, you might choose calcium nitrate over cyclohexane.

flammability

Flammability refers to a material's ability to catch fire when exposed to air. It is an essential property for safety and industrial applications. Cyclohexane, being a hydrocarbon, is flammable and burns in air, releasing carbon dioxide and water.

In contrast, calcium nitrate is not flammable. Instead, it acts as an oxidizer, meaning it can support combustion of other materials by releasing oxygen. Understanding the flammability of substances is key for handling, storage, and use, ensuring safety in various settings.

Hence, cyclohexane requires more caution in environments with fire hazards compared to calcium nitrate.

state of matter

The state of matter characterizes a substance's physical form at a given temperature and pressure. The primary states are solid, liquid, and gas. At room temperature, cyclohexane is a liquid because its molecules have enough energy to move past each other but not enough to escape into the gas phase.

Conversely, calcium nitrate remains a solid at room temperature with its molecules vibrating in fixed positions due to strong ionic bonds holding them together. Knowing the state of matter aids in determining how to store and manipulate substances.

For instance, you’d store liquid cyclohexane in sealed containers to prevent evaporation, while solid calcium nitrate can be stored more openly as it doesn’t pose evaporation risks.