Question

endothermic reaction
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draw an example showing reactants an

Explanation:

1. Define: An endothermic reaction is a chemical process that absorbs heat energy from its surroundings, resulting in a net increase in the enthalpy of the system.
2. Example: A common example is the photosynthesis reaction in plants, where carbon dioxide and water absorb energy from sunlight to produce glucose and oxygen. The balanced chemical equation is $6\text{CO}_2 + 6\text{H}_2\text{O} \xrightarrow{\text{sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$.
3. Draw (Energy Profile): The energy profile has reactants at a lower energy level than products, with a positive activation energy peak. The difference between product and reactant energy equals the absorbed heat ($\Delta H > 0$). Label the axes: y-axis = "Potential Energy", x-axis = "Reaction Progress". Mark reactants ($6\text{CO}_2 + 6\text{H}_2\text{O}$), products ($\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$), activation energy barrier, and $\Delta H$ as the upward arrow between reactant and product energy levels.

Answer:

1. Define: A chemical reaction that absorbs heat from its surroundings, with a positive change in enthalpy ($\Delta H > 0$).
2. Example: Photosynthesis: $6\text{CO}_2 + 6\text{H}_2\text{O} \xrightarrow{\text{sunlight}} \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$
3. Draw: An energy profile graph where:

• X-axis: Reaction Progress, Y-axis: Potential Energy
• Reactants are plotted at a lower energy level
• A peak (activation energy) sits between reactants and products
• Products are plotted at a higher energy level than reactants
• An upward arrow labeled $\Delta H$ connects reactant and product energy levels, indicating absorbed heat