# Relation between temperature and boiling point?

• Decimal
In summary, the conversation discusses the relationship between the latent heat of vaporization and the temperature of a substance. The latent heat and entropy change of vaporization are both dependent on temperature, assuming constant pressure. The change in Gibbs energy for a phase change is equal to zero, allowing for the expression of the boiling point in terms of latent heat and entropy change. The boiling point is dependent on temperature, but also on the outside pressure, as it occurs when the equilibrium vapor pressure is equal to the outside pressure.
Decimal
Hello,

I am encountering some confusion with the relation between the latent heat of vaporization and the temperature of a substance. I understand both the latent heat and the entropy change of vaporization are dependent on the temperature, assuming the pressure is held constant. However given that the change in Gibbs energy for a phase change is equal to zero, one can express the boiling point of a substance in the latent heat and entropy change: $$\Delta g = l_{23} - T_{boil} s_{23} = 0$$ $$T_{boil} = \frac {l_{23}}{s_{23}}$$ Here 2 and 3 refer to the fluid and gas states of the substance respectively. Doesnt this imply that the boiling point of a substance is dependent on the temperature? How can I interpret this? I always thought of the boiling point as a quantity dependent on the outside pressure.

Thanks!

You are aware that there is a one-to-one relationship between the temperature and the equilibrium vapor pressure, correct? And that boiling occurs when the equilibrium vapor pressure is equal to the outside pressure, correct?

Bystander

## 1. How does temperature affect the boiling point of a substance?

The boiling point of a substance is directly related to its temperature. As the temperature of a substance increases, its molecules gain more energy and move faster. This increased movement causes the molecules to overcome their intermolecular forces and escape into the gas phase, resulting in a higher boiling point.

## 2. Is there a specific temperature at which all substances boil?

No, the boiling point of a substance varies depending on its chemical composition and atmospheric pressure. For example, water boils at 100 degrees Celsius at sea level, but at higher elevations where atmospheric pressure is lower, it will boil at a lower temperature.

## 3. How does pressure affect the boiling point of a substance?

Pressure and temperature have an inverse relationship when it comes to boiling point. As pressure increases, the boiling point of a substance increases as well. This is because higher pressure compresses the molecules, making it more difficult for them to escape into the gas phase.

## 4. Why does water have a higher boiling point than other substances?

Water has a higher boiling point than most substances due to its strong intermolecular forces. The hydrogen bonding between water molecules requires more energy to overcome, resulting in a higher boiling point compared to substances with weaker intermolecular forces.

## 5. Can the boiling point of a substance change?

Yes, the boiling point of a substance can change depending on external factors such as pressure and impurities. Additionally, changes in the chemical composition of a substance can also affect its boiling point. For example, adding salt to water increases its boiling point due to the disruption of the hydrogen bonds between water molecules.

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