To determine which reaction is endothermic among the given reactions, we need to understand what characterizes an endothermic reaction. An endothermic reaction is one that absorbs energy from its surroundings, usually in the form of heat. This is in contrast to an exothermic reaction, which releases energy into its surroundings.
Let's analyze each reaction step-by-step:
1. Reaction 1: [tex]\(HCl + NaOH \rightarrow NaCl + H _2 O +58\: kJ\)[/tex]
- This reaction releases 58 kJ of energy as a product.
- Since it releases energy, it is exothermic.
2. Reaction 2: [tex]\(6 CO _2 + 12 H _2 O + \text{energy} \rightarrow C _6 H _{12} O _6 + 6 O _2 + 6 H _2 O\)[/tex]
- This reaction has energy listed as a reactant.
- This means that energy is absorbed to form the products.
- Therefore, this reaction is endothermic.
3. Reaction 3: [tex]\(2 Na + Cl _2 \rightarrow 2 NaCl + \text{energy}\)[/tex]
- This reaction has energy listed as a product.
- Since energy is released, it is exothermic.
4. Reaction 4: [tex]\(2 C _2 H _6 + 7 O _2 \rightarrow 4 CO _2 + 6 H _2 O +\ 2,502\: kJ\)[/tex]
- This reaction releases 2,502 kJ of energy as a product.
- As it releases energy, it is exothermic.
From the above analysis, we can conclude that the endothermic reaction is:
[tex]\[
6 CO _2 + 12 H _2 O + \text{energy} \rightarrow C _6 H _{12} O _6 + 6 O _2 + 6 H _2 O
\][/tex]
Thus, the endothermic reaction is the second one.
