Environment, health and safety

Which correctly describes a hazard of hydrogen gas, used in epitaxial growth and annealing?

  1. AIts range of concentrations in air that can burn or explode is very wide, about 4 to 75%, and the energy needed to ignite it is small
  2. BIt is heavier than air and tends to pool on the floor
  3. CIt dissolves in water to form a strong acid
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Answer: A. Its range of concentrations in air that can burn or explode is very wide, about 4 to 75%, and the energy needed to ignite it is small

Hydrogen's explosive range in air is very wide, about 4 to 75 vol%, and its minimum ignition energy is small, so even slight static discharge can ignite it. Being far lighter than air, it tends to collect near ceilings, so detection and ventilation near ceilings and leak control in piping are important.

  • A. Correct. It is a gas with a wide explosive range that ignites easily.
  • B. Hydrogen is the lightest gas and collects high up.
  • C. Hydrogen does not dissolve in water to form an acid.
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