Liquid hydrogen

High school (ages 12+)
Science & Technology

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/liquid-hydrogen

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the thermodynamic minimum liquefaction energy?3.3 kWh/kg (12 MJ/kg)
2. What is the typical industrial liquefaction energy?10–13 kWh/kg (36–47 MJ/kg)
3. What is liquid hydrogen and why does it need to be so cold?Liquid hydrogen is hydrogen that has been cooled below 33 K, and at normal pressure it must be kept at 20.28 K (-252.87 °C).
4. How do we turn hydrogen gas into liquid hydrogen?We use refrigeration cycles with compressors and heat exchangers to remove heat from the gas, but it takes a lot of energy—about 10–13 kWh for each kilogram of liquid.

Critical Temperature: The temperature above which a gas cannot be liquefied, no matter the pressure.
Specific Impulse: A measure of how efficiently a rocket engine uses propellant.
Cryogenic Dewars: Highly insulated containers designed to store extremely cold liquids like liquid hydrogen.