When hydrogen burns in air water is formed, the equation for this reaction is:
2H2(g) +O2(g) -> 2H2O(g) delta H = -484kj
A. Which has the greater amount of energy? Water or the mixture of hydrogen and oxygen? Give reason for your answer
B. Draw energy profile diagram for the reaction between hydrogen and oxygen to form water
Delta H is negative which means the reaction gives off energy and that means the reactants have more energy than the products.
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To determine which has the greater amount of energy, water or the mixture of hydrogen and oxygen, we need to compare the enthalpy (energy) change of the reaction.
In this particular reaction, the enthalpy change (delta H) is given as -484 kJ. A negative value for delta H indicates that the reaction is exothermic, meaning it releases energy.
A. Reasoning:
When hydrogen and oxygen react to form water, the reaction releases energy in the form of heat. The energy is given off because the bonds between the atoms in the reactants (hydrogen and oxygen) are weaker than the bonds in the product (water). As a result, forming the water molecule leads to a decrease in the overall energy content of the system.
So, water has less energy than the initial mixture of hydrogen and oxygen. Therefore, the initial mixture of hydrogen and oxygen has a greater amount of energy compared to water.
B. Energy profile diagram:
To draw an energy profile diagram, we will need to show the relative energy levels of the reactants, transition state, and products.
The energy profile diagram will consist of two horizontal lines, representing the energy of the reactants and products respectively. The transition state will be shown as a peak on the diagram.
Starting with the reactants:
- Draw a horizontal line to represent the energy level of the hydrogen and oxygen molecules (2H2(g) + O2(g)).
- Label this line with the energy value.
Next, the transition state:
- Draw a peak or a curve between the reactants and products to represent the transition state.
- The peak should have an energy value higher than that of the reactants.
Lastly, the products:
- Draw another horizontal line to represent the energy level of the water molecules (2H2O(g)).
- Label this line with the energy value.
Make sure to label the axes of the diagram with "energy" and "reaction progress" to indicate the changes in energy as the reaction progresses.
Overall, the diagram should show a decrease in energy from the reactants to the products, with the transition state representing the highest energy point in the reaction.