Which reaction is an example of a balanced endothermic reaction?
Answer Options:
Select one of four
$N_2(g)+O_2(g)-\text { heat } \rightarrow 2 NO(g)$
$N_2(g)+O_2(g)+\text { heat } \rightarrow 2 N(g)$
$N_2(g)+O_2(g)+\text { heat } \rightarrow 2 NO(g)$
$N_2(g)+O_2(g) \rightarrow 2 NO(g)$
Answer (2)
An endothermic reaction absorbs heat, while a balanced reaction maintains equal atom counts on both sides.
Option 1 is exothermic.
Option 2 is endothermic but unbalanced.
Option 3 is both endothermic and balanced: N 2 ( g ) + O 2 ( g ) + heat → 2 NO ( g ) .
Option 4 doesn't explicitly show heat absorption.
The balanced endothermic reaction is \boxed{N_2(g) + O_2(g) + \text{ heat } \rightarrow 2NO(g)}.
Explanation
Understanding the Problem We need to identify a balanced endothermic reaction from the given options. An endothermic reaction absorbs heat, and a balanced reaction has the same number of atoms of each element on both sides of the equation.
Analyzing Each Option Let's examine each reaction:
Option 1: N 2 ( g ) + O 2 ( g ) − heat → 2 NO ( g ) . This reaction releases heat, making it exothermic, not endothermic. However, it is balanced.
Option 2: N 2 ( g ) + O 2 ( g ) + heat → 2 N ( g ) . This reaction absorbs heat, so it is endothermic. But, it is not balanced because there are two oxygen atoms on the left and none on the right.
Option 3: N 2 ( g ) + O 2 ( g ) + heat → 2 NO ( g ) . This reaction absorbs heat, so it is endothermic. It is also balanced because there are two nitrogen atoms and two oxygen atoms on both sides.
Option 4: N 2 ( g ) + O 2 ( g ) → 2 NO ( g ) . This reaction does not explicitly show heat being absorbed, but it is balanced.
Identifying the Correct Reaction The reaction that is both endothermic (absorbs heat) and balanced is option 3.
Final Answer Therefore, the balanced endothermic reaction is: N 2 ( g ) + O 2 ( g ) + heat → 2 NO ( g ) .
Examples
Endothermic reactions are crucial in cooking. For instance, baking a cake involves endothermic reactions where the batter absorbs heat from the oven to transform into a solid cake. Similarly, in cold packs used for injuries, endothermic reactions absorb heat from the surroundings, providing a cooling effect. Understanding these reactions helps us control and utilize energy in various practical applications.
The balanced endothermic reaction from the provided options is N 2 ( g ) + O 2 ( g ) + heat → 2 NO ( g ) . This equation indicates that the reaction absorbs heat and is balanced, with equal numbers of nitrogen and oxygen atoms on both sides. Thus, the correct choice is the third option.
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