Water forms according to the equation below
[tex]2 H_2(g)+O_2(g) \rightarrow 2 H_2 O(g) \quad \Delta H_{(x n}=183.64 kJ[/tex]
How much energy is released during the formation of [tex]1 mol H _2 O ( g )[/tex]?
Answer (1)
Divide the given enthalpy change ( Δ H r x n = − 183.64 k J ) by 2 to find the energy released per mole of H 2 O ( g ) .
Calculate 2 − 183.64 k J = − 91.82 k J .
Take the absolute value to find the energy released, which is 91.82 kJ.
The energy released during the formation of 1 mole of H 2 O ( g ) is 91.82 kJ.
Explanation
Understanding the Problem We are given the reaction: 2 H 2 ( g ) + O 2 ( g ) i g h t ha r p oo n u p 2 H 2 O ( g ) with Δ H r x n = − 183.64 k J . This means that when 2 moles of H 2 O ( g ) are formed, 183.64 kJ of energy is released. We want to find the amount of energy released when 1 mole of H 2 O ( g ) is formed.
Finding Energy per Mole Since the formation of 2 moles of H 2 O ( g ) releases 183.64 kJ of energy, we can find the energy released per mole by dividing the total energy released by the number of moles formed.
Calculating Energy Released To find the energy released during the formation of 1 mole of H 2 O ( g ) , we divide the given Δ H r x n by 2: 2 − 183.64 k J = − 91.82 k J The negative sign indicates that the energy is released (exothermic reaction).
Final Answer The amount of energy released during the formation of 1 mole of H 2 O ( g ) is the absolute value of the result, which is 91.82 kJ.
Examples
This concept is crucial in understanding energy production in various chemical reactions, such as combustion. For example, when designing a hydrogen fuel cell, knowing the energy released per mole of water formed helps in determining the efficiency and energy output of the cell. If a fuel cell produces 10 moles of water, the total energy released would be 10 × 91.82 k J = 918.2 k J , allowing engineers to optimize the fuel cell's performance and energy conversion rates.
