Problem 81 - Chemistry: An Atoms-Focused Approach

Question

Liquid helium boils at \(4.2 \mathrm{K}\). What is the boiling point of helium in degrees Celsius?

Step-by-Step Solution

Answer

Answer: The boiling point of liquid helium in degrees Celsius is -268.95°C.

Step 1: Identify the boiling point in Kelvin

The given boiling point of liquid helium is \(4.2 \mathrm{K}\).

Step 2: Use the formula to convert from Kelvin to Celsius

Now we will use the formula mentioned earlier to convert the boiling point from Kelvin to degrees Celsius: $$ °C = K - 273.15 $$ In our case, \(K = 4.2 \mathrm{K}\). So the conversion formula becomes: $$ °C = 4.2 - 273.15 $$

Step 3: Calculate the boiling point in degrees Celsius

By performing the subtraction: $$ °C = -268.95 $$ Thus, the boiling point of liquid helium in degrees Celsius is \(-268.95 \, ^{\circ}\mathrm{C}\).

Key Concepts

Kelvin to Celsius conversion

The Kelvin to Celsius conversion is a key concept in temperature measurement. The Kelvin scale is often used in scientific measurements because it begins at absolute zero, the point where all atomic movement stops. Celsius, on the other hand, is more commonly used in everyday life and starts at the freezing point of water.

To convert a temperature from Kelvin to Celsius, a simple formula is used:

• °C = K - 273.15

This formula subtracts 273.15 from the Kelvin temperature to find its equivalent in Celsius. For example, liquid helium, which boils at 4.2 K, can be converted with this formula to Celsius as follows:

• °C = 4.2 K - 273.15 = -268.95 °C

This conversion indicates that liquid helium has an extremely low boiling point, demonstrating why it is used in ultra-low temperature applications.

Liquid helium properties

Liquid helium is an extraordinary substance, primarily because of its extremely low boiling point of only 4.2 K, which translates to -268.95 °C. This property makes it one of the coldest known liquids and a vital substance in cryogenics, the science of very low temperatures.

Some important properties of liquid helium include:

• Helium remains a liquid down to absolute zero under normal atmospheric pressure, while most substances solidify.
• It is used in superconducting magnets due to its ability to reach and maintain extremely low temperatures.
• It exhibits superfluidity, which means it can flow without viscosity or friction under certain conditions.

Understanding these properties is important for physicists and engineers who work with supercooling processes and equipment.

Temperature conversion formula

The temperature conversion formula is an essential tool in science and everyday applications for translating temperatures between different scales. Common scales include Kelvin, Celsius, and Fahrenheit.

The Kelvin to Celsius formula, as discussed earlier, is straightforward as it involves subtraction:

• °C = K - 273.15

Conversions between other temperature scales require different formulas:

• For Fahrenheit to Celsius: °C = (°F - 32) × 5/9
• For Celsius to Fahrenheit: °F = °C × 9/5 + 32
• For Kelvin to Fahrenheit: °F = (K - 273.15) × 9/5 + 32

These formulas are handy not only for chemistry and physics but also in industries requiring precise temperature control and monitoring. Recognizing and applying these formulas allows for seamless conversions within any scientific or everyday context.