Question

The vapor pressure of methanol is 1 atm at \(65{ }^{\circ} \mathrm{C}, 2 \mathrm{~atm}\) at \(84^{\circ} \mathrm{C}, 5 \mathrm{~atm}\) at \(112^{\circ} \mathrm{C}, 10 \mathrm{~atm}\) at \(138{ }^{\circ} \mathrm{C}_{i}\) and \(20 \mathrm{~atm}\) at \(168^{\circ} \mathrm{C} .\) What is the normal boiling point of methanol?

Short answer

The normal boiling point of methanol is 65°C.

Step-by-step solution

Understanding the Problem

To find the normal boiling point of methanol, we need to determine the temperature at which the vapor pressure of methanol equals 1 atm. The normal boiling point is defined as the temperature at which the substance's vapor pressure equals atmospheric pressure, typically 1 atm.

Review Given Data

The problem provides the vapor pressure of methanol at various temperatures: - 1 atm at 65°C - 2 atm at 84°C - 5 atm at 112°C - 10 atm at 138°C - 20 atm at 168°C Already from the data provided, we see that at 65°C, the vapor pressure is 1 atm.

Identify the Normal Boiling Point

Since the normal boiling point is where the vapor pressure is exactly 1 atm, and considering the data shows that the vapor pressure of methanol is 1 atm at 65°C, we can conclude that the normal boiling point of methanol is 65°C.

Conclusion

Based on the provided data, the temperature at which the pressure of methanol matches 1 atm (atmospheric pressure) is at 65°C. Thus, the normal boiling point of methanol is 65°C.

Key concepts

Understanding Vapor Pressure

Vapor pressure is a key concept when discussing the boiling point of a substance. It represents the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. When the vapor pressure equals atmospheric pressure, the liquid reaches its boiling point and begins to convert into gas. This is why knowing the vapor pressure at different temperatures helps us determine a substance's boiling point.

In the scenario given, the vapor pressure of methanol at various temperatures allows us to identify when it reaches 1 atm, which is the standard atmospheric pressure at sea level. A liquid boils when its vapor pressure matches the external pressure. Therefore, the understanding of vapor pressure is crucial to finding the point where methanol will start to boil under normal conditions.

Properties and Role of Methanol

Methanol, also known as wood alcohol, is a light, volatile, and flammable liquid with the chemical formula CH₃OH. It's notable for being the simplest alcohol and is used in various industrial and technical applications, such as antifreeze, solvent, and fuel.

One important feature of methanol is its relatively low boiling point when compared to water, which reflects its lower molecular weight and weaker intermolecular forces. Methanol has a normal boiling point at just 65°C (149°F).

• Methanol boils at 65°C when the vapor pressure equals 1 atm.
• It's often used in laboratory settings due to its easy handling and compatibility with many reactions.

The knowledge of methanol's properties is essential when handling or discussing its uses, especially when considering boiling points affected by vapor pressure.

The Process of Temperature Measurement

Accurate temperature measurement is pivotal in determining when a substance reaches its boiling point. This involves using thermometers or other devices to measure temperature with precision, thereby ensuring experiments and findings are reliable.

• Utilize calibrated thermometers for accuracy.
• Ensure conditions are stable to avoid fluctuations.
• Avoid contact with surfaces that may alter readings.

In the context of methanol's boiling point, careful measurement is necessary to confirm that the temp at which vapor pressure reaches 1 atm is indeed precisely noted at 65°C. Missteps in measuring temperature can lead to incorrect data, affecting both scientific and practical outcomes.