To determine which reaction is endothermic, we need to understand the basic definitions of exothermic and endothermic reactions.
Exothermic reactions release energy into the surroundings, often in the form of heat, light, or sound. These reactions usually have a negative energy change or release a specified amount of energy as a product.
Endothermic reactions absorb energy from the surroundings. These reactions usually have a positive energy change or require an input of energy to proceed.
Let's analyze each reaction:
1. Reaction 1:
[tex]\[
\text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2 \text{O} + 58 \text{ kJ}
\][/tex]
This reaction releases 58 kJ of energy. Therefore, it is exothermic.
2. Reaction 2:
[tex]\[
6 \text{CO}_2 + 12 \text{H}_2 \text{O} + \text{energy} \rightarrow \text{C}_6 \text{H}_{12} \text{O}_6 + 6 \text{O}_2 + 6 \text{H}_2 \text{O}
\][/tex]
This reaction requires input of energy to proceed, indicating that it absorbs energy. Therefore, it is endothermic.
3. Reaction 3:
[tex]\[
2 \text{Na} + \text{Cl}_2 \rightarrow 2 \text{NaCl} + \text{energy}
\][/tex]
This reaction releases energy as a product. Therefore, it is exothermic.
4. Reaction 4:
[tex]\[
2 \text{C}_2 \text{H}_6 + 7 \text{O}_2 \rightarrow 4 \text{CO}_2 + 6 \text{H}_2 \text{O} + 2,502 \text{ kJ}
\][/tex]
This reaction releases 2,502 kJ of energy. Therefore, it is exothermic.
By comparing all the given reactions, we can see that only the second reaction (Reaction 2):
[tex]\[
6 \text{CO}_2 + 12 \text{H}_2 \text{O} + \text{energy} \rightarrow \text{C}_6 \text{H}_{12} \text{O}_6 + 6 \text{O}_2 + 6 \text{H}_2 \text{O}
\][/tex]
is endothermic.
Hence, the reaction that is endothermic is Reaction 2.
