Question

which reaction is endothermic?
hcl + naoh → nacl + h₂o + 58 kj
6co₂ + 12h₂o + energy → c₆h₁₂o₆ + 6o₂ + 6h₂o
2na + cl₂ → 2nacl + energy
2c₂h₆ + 7o₂ → 4co₂ + 6h₂o + 2,502 kj

Explanation:

Step1: Define endothermic reaction

An endothermic reaction absorbs energy.

Step2: Analyze each option

In the first, third and fourth reactions, energy is on the product - side (released). In 6CO₂ + 12H₂O + energy → C₆H₁₂O₆ + 6O₂ + 6H₂O, energy is on the reactant - side (absorbed).

Answer:

6CO₂ + 12H₂O + energy → C₆H₁₂O₆ + 6O₂ + 6H₂O