At What Temperature Does Water Turn into Vapor?


Water is a fundamental substance that exists in three different states: solid (ice), liquid (water), and gas (vapor). The transition from liquid to gas occurs when water reaches its boiling point and turns into vapor. In this article, we will explore the temperature at which water undergoes this transformation, as well as the factors that influence it.

Understanding the Boiling Point of Water

The boiling point of water is the temperature at which it changes from a liquid state to a gaseous state, resulting in the formation of water vapor. This transition occurs when the vapor pressure of the liquid equals the atmospheric pressure exerted on its surface. The boiling point is influenced by various factors, such as altitude, pressure, and the presence of impurities.

1. Factors Affecting the Boiling Point

1.1 Altitude: As we ascend to higher altitudes, the atmospheric pressure decreases. This reduction in pressure lowers the boiling point of water. For example, at sea level, water boils at 100 degrees Celsius (212 degrees Fahrenheit), but at the top of Mount Everest, where the atmospheric pressure is significantly lower, water boils at around 68 degrees Celsius (154 degrees Fahrenheit).

1.2 Pressure: Increasing or decreasing the pressure can also impact the boiling point of water. When pressure is increased, such as in a pressure cooker, the boiling point of water rises. Conversely, reducing pressure, as in a vacuum, lowers the boiling point.

1.3 Impurities: Impurities in water, such as dissolved salts or minerals, affect its boiling point. These impurities disrupt the formation of water vapor bubbles, requiring higher temperatures to reach the boiling point. This phenomenon is commonly observed when cooking with salted water.

2. The Standard Boiling Point of Water

The standard boiling point of water is defined as the temperature at which water boils at a pressure of 1 atmosphere (atm), which is equivalent to 101.325 kilopascals (kPa) or 760 millimeters of mercury (mmHg). At this standard atmospheric pressure, water boils at precisely 100 degrees Celsius (212 degrees Fahrenheit).

Measuring the Boiling Point

There are several methods to determine the boiling point of water accurately. One common approach is to use a laboratory apparatus called a “boiling point apparatus” or a “thermometer.” This apparatus consists of a glass tube with a bulb at the bottom containing a liquid, typically mercury or alcohol, that expands when heated. The liquid rises in the tube, indicating the temperature at which boiling occurs.

1. Boiling Point Determination Process

1.1 Set up the boiling point apparatus by attaching the thermometer to a stand or clamp, ensuring it is positioned at the same height as the water surface.

1.2 Fill a heat-resistant container, such as a beaker or flask, with distilled water, leaving some space for the water to boil and bubble without overflowing.

1.3 Place the container on a heat source, such as a Bunsen burner or hot plate, and apply heat gradually. Stir the water gently to distribute the heat evenly.

1.4 Observe the thermometer closely as the temperature rises. The boiling point is reached when the temperature remains constant despite continued heating. This indicates that the water is transforming into vapor at a steady rate.

1.5 Record the observed temperature as the boiling point of water under the specific experimental conditions.

FAQs about the Boiling Point of Water

1. Why does water boil at different temperatures at different altitudes?

Water boils at varying temperatures at different altitudes due to the changes in atmospheric pressure. As altitude increases, the atmospheric pressure decreases, and therefore, the boiling point of water lowers.

2. Can water boil at temperatures below 100 degrees Celsius?

Yes, water can boil at temperatures below 100 degrees Celsius when the atmospheric pressure is reduced. For example, in a vacuum chamber, water can boil even at room temperature.

3. Do impurities always increase the boiling point of water?

No, impurities in water can both increase or decrease its boiling point, depending on the specific impurities present. Dissolved salts and minerals tend to raise the boiling point, while certain volatile substances can lower it.

4. Why does water boil faster in a pressure cooker?

A pressure cooker increases the pressure inside the cooking vessel, raising the boiling point of water. The higher temperature achieved allows for faster cooking times.

5. How does the boiling point change with increased pressure?

An increase in pressure raises the boiling point of water. This is why food cooks more quickly in a pressure cooker, as the higher pressure allows for higher temperatures and faster cooking.

6. Can the boiling point of water exceed 100 degrees Celsius?

Under normal atmospheric conditions, the boiling point of water cannot exceed 100 degrees Celsius. However, by increasing the pressure, such as in a pressure cooker, the boiling point can be raised above 100 degrees Celsius.


The boiling point of water is a critical property affected by various factors, including altitude, pressure, and impurities. Understanding these factors helps explain why water boils at different temperatures under different conditions. By knowing the boiling point, we can harness the power of steam and vaporization in various industrial processes and everyday activities, such as cooking and heating.

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