The reaction C2H6 → C2H + H2 is known as

Analyze the question: The reaction shows ethane (C₂H₆) losing hydrogen (H₂) as a product. We need the name for this type of reaction.

(Note: the product "C₂H" in the question is most likely a typing error for C₂H₄, ethene. The balanced reaction is C₂H₆ → C₂H₄ + H₂. The type of reaction is clear either way, because H₂ is removed.)

Concept:

• Dehydration: removal of water (H₂O).
• Dehydrogenation: removal of hydrogen (H₂) from a compound.
• Displacement: a more reactive element displaces a less reactive one from a compound.
• Hydrogenation: addition of hydrogen (H₂) to a compound, e.g. alkene → alkane with a Ni catalyst.
• Reduction: gain of hydrogen, loss of oxygen, or gain of electrons.

Solution:

1. Ethane (C₂H₆) is an alkane, a saturated hydrocarbon.
2. It loses a molecule of H₂ and becomes an unsaturated compound (an alkene, with a double bond).
3. Loss of hydrogen from a molecule is called dehydrogenation.
4. Hydrogenation is the reverse process: C₂H₄ + H₂ → C₂H₆ (Ni catalyst, about 200°C).

Answer: B. dehydrogenation.

Tip: Look at the prefix and root.

• "De-" means removal, and "hydrogen" is what is removed, so de-hydrogen-ation means hydrogen is removed.
• "Hydro-" with no "de-" means hydrogen is added.
• Alkane → alkene means hydrogen is lost (dehydrogenation).
• Alkene → alkane means hydrogen is gained (hydrogenation).