Question

The vapor pressure of acetone is \(1 \mathrm{~mm} \mathrm{Hg}\) at \(-59^{\circ} \mathrm{C}\) \(10 \mathrm{~mm} \mathrm{Hg}\) at \(-31{ }^{\circ} \mathrm{C}, 100 \mathrm{~mm} \mathrm{Hg}\) at \(8{ }^{\circ} \mathrm{C}, 400 \mathrm{~mm} \mathrm{Hg}\) at \(40^{\circ} \mathrm{C},\) and \(760 \mathrm{~mm} \mathrm{Hg}\) at \(56^{\circ} \mathrm{C}\). What is the normal boiling point of acetone?

Short answer

The normal boiling point of acetone is \(56^{\circ}C\).

Step-by-step solution

Introduction to Vapor Pressure and Boiling Point

The normal boiling point of a substance is the temperature at which its vapor pressure equals the standard atmospheric pressure, which is 760 mm Hg. To solve for the boiling point of acetone, we must identify the temperature at which its vapor pressure is 760 mm Hg from the provided data.

Analyzing Given Data

Review the provided vapor pressures and corresponding temperatures: - At \( -59^{\circ}C \), vapor pressure is \( 1 \, mm \, Hg \).- At \( -31^{\circ}C \), vapor pressure is \( 10 \, mm \, Hg \).- At \( 8^{\circ}C \), vapor pressure is \( 100 \, mm \, Hg \).- At \( 40^{\circ}C \), vapor pressure is \( 400 \, mm \, Hg \).- At \( 56^{\circ}C \), vapor pressure is \( 760 \, mm \, Hg \).

Identify the Normal Boiling Point

According to the data, at \( 56^{\circ}C \), acetone's vapor pressure is \( 760 \, mm \, Hg \). This matches the standard atmospheric pressure. Thus, \( 56^{\circ}C \) is the temperature at which acetone will boil under normal atmospheric conditions, making it the normal boiling point of acetone.

Key concepts

Vapor Pressure

Vapor pressure is a crucial concept in understanding the boiling process of any substance. It refers to the pressure exerted by a vapor in equilibrium with its liquid or solid phase. Imagine a closed container with a liquid. Over time, some molecules will escape from the surface of the liquid and form a vapor above it. The pressure these gas molecules exert against the walls of the container is the vapor pressure.

Vapor pressure varies with temperature. As the temperature increases, more molecules have enough energy to escape the liquid, increasing the vapor pressure. Each substance has its own unique vapor pressure characteristics, depending on its molecular structure. For example, acetone has a vapor pressure of 760 mm Hg at 56°C.

Knowing the vapor pressure at different temperatures helps determine when the substance will boil. Understanding these principles can help in solving problems related to boiling points and other thermodynamic calculations. Remember: it's all about the balance between opposing forces of evaporation and condensation.

Normal Boiling Point

The normal boiling point of a substance is defined as the temperature at which its vapor pressure equals the external atmospheric or ambient pressure. For a location at sea level, this pressure is typically 760 mm Hg.

When the vapor pressure of a liquid matches the surrounding atmospheric pressure, the liquid begins to boil. This means that the molecules have enough energy to change from the liquid phase to the gas phase freely.

In our example, acetone has a normal boiling point of 56°C. This is the temperature at which acetone's vapor pressure equals 760 mm Hg, making it boil under standard sea-level conditions.

• Acetone transitions smoothly from liquid to gas at this temperature.
• This temperature is unique for each substance due to differing molecular structures and intermolecular forces.

Understanding the concept of normal boiling point is vital for processes involving heating and distillation in chemistry and industrial applications.

Atmospheric Pressure

Atmospheric pressure is the force exerted by the weight of the air above us. It is a fundamental concept in weather systems and boiling processes. At sea level, atmospheric pressure is standardized at around 760 mm Hg or 1 atm. This pressure can vary based on altitude and weather conditions, but for most practical and scientific problems, 760 mm Hg is used as the standard reference.

In the context of boiling, atmospheric pressure plays a critical role. All substances boil when their vapor pressure equals the surrounding atmospheric pressure.

• For example, water boils at 100°C under normal atmospheric pressure.
• In higher altitudes where atmospheric pressure is lower, water boils at a lower temperature.

Understanding atmospheric pressure allows us to see why boiling points differ at various altitudes and under different conditions. In our problem, the normal boiling point of acetone is found by balancing its vapor pressure with the acknowledged atmospheric pressure of 760 mm Hg.