Question

Pure acetic acid, which gives the sour taste to vinegar, has a melting point of \(16.7{ }^{\circ} \mathrm{C}\) and a boiling point of \(118^{\circ} \mathrm{C}\). Predict the physical state of acetic acid when the ambient temperature is \(10^{\circ} \mathrm{C}\).

Short answer

Acetic acid is solid at \(10{ }^{\circ} \mathrm{C}\).

Step-by-step solution

Understanding the Problem

We need to determine the physical state of a substance, in this case, acetic acid, based on its melting point and boiling point. We are given that acetic acid has a melting point of \(16.7{ }^{\circ} \mathrm{C}\) and a boiling point of \(118{ }^{\circ} \mathrm{C}\). The ambient temperature is \(10{ }^{\circ} \mathrm{C}\).

Identify State Change Temperatures

Acetic acid transitions phases at its melting and boiling points. Below the melting point of \(16.7{ }^{\circ} \mathrm{C}\), it is solid. Between \(16.7{ }^{\circ} \mathrm{C}\) and \(118{ }^{\circ} \mathrm{C}\), it is liquid. Above \(118{ }^{\circ} \mathrm{C}\), it is in the gaseous state.

Compare Ambient Temperature

We compare the given ambient temperature of \(10{ }^{\circ} \mathrm{C}\) to the melting and boiling points. Since \(10{ }^{\circ} \mathrm{C}\) is below the melting point \(16.7{ }^{\circ} \mathrm{C}\), acetic acid will be in the solid state.

Key concepts

Melting Point of Acetic Acid

The melting point of a substance is the temperature at which it changes from a solid to a liquid. For acetic acid, this transition occurs at \(16.7{ }^{\circ} \mathrm{C}\). At this specific temperature, the molecules gain enough energy to break free from the rigid structure of a solid, allowing them to move past each other, thus becoming a liquid.

Understanding the melting point is crucial because it tells us about the energy contained in the bonds between molecules. A higher melting point generally indicates stronger bonds. For acetic acid, its relatively low melting point compared to other similar compounds suggests that the forces holding the acetic acid molecules in place are not exceedingly strong.

When analyzing the physical state of acetic acid at a given temperature, it’s important to remember that if the temperature is below \(16.7{ }^{\circ} \mathrm{C}\), acetic acid will remain solid. For example, at \(10{ }^{\circ} \mathrm{C}\), we can predict acetic acid is a solid because it hasn’t reached the energy level required to melt.

Boiling Point of Acetic Acid

The boiling point is the temperature at which a liquid turns into a gas. For acetic acid, this occurs at \(118{ }^{\circ} \mathrm{C}\). At this temperature, the liquid acetic acid molecules have enough energy to break away from the liquid phase into the gaseous phase. This phase change requires much more energy than moving from solid to liquid.

Boiling point information helps us understand the volatility of a substance. Acetic acid has a relatively high boiling point for a simple carboxylic acid, indicating that its molecules are held together tightly when in the liquid phase. These stronger interactions are mainly due to hydrogen bonds which need to be broken for boiling to occur.

As with melting point, knowing the boiling point can aid in practical applications and predictions. If the temperature is above \(118{ }^{\circ} \mathrm{C}\), acetic acid will be in a gaseous state. But, at temperatures like \(10{ }^{\circ} \mathrm{C}\), which is far below its boiling point, acetic acid will still safely remain in a solid or liquid phase.

Physical State Prediction of Acetic Acid

Predicting the physical state of acetic acid based on temperature involves comparing the temperature with its melting and boiling points. At the melting point, acetic acid transitions from solid to liquid, whereas at the boiling point, it shifts from liquid to gas.

To predict the physical state at an ambient temperature of \(10{ }^{\circ} \mathrm{C}\), we look to see where this value falls relative to the melting and boiling points. Since \(10{ }^{\circ} \mathrm{C}\) is below \(16.7{ }^{\circ} \mathrm{C}\), acetic acid will not have enough energy to melt, remaining solid. It is also far below \(118{ }^{\circ} \mathrm{C}\), so it is not in a gaseous state.

This kind of temperature and state analysis is fundamental in chemistry because it allows us to predict how substances will behave in different environments. It is a concept widely applied in engineering, chemistry, and everyday life, making it critical for scientific understanding and reasoning. Understanding the interaction of temperature with melting and boiling points can guide usage and storage for many substances effectively.