Question

Thinking about enthalpy and a change in enthalpy, explain how you could find the total change of enthalpy based on this diagram. Is the enthalpy positive or negative?

Answer 1

In chemistry, the total change in enthalpy of a reaction can be determined by comparing the potential energy of the reactants to the potential energy of the products. For an endothermic reaction, the enthalpy change is positive because energy is absorbed. Conversely, for an exothermic reaction, the enthalpy change is negative because energy is released.

Step-by-step explanation:

The change in enthalpy of a reaction is determined by the differences in enthalpy of the reactants and products. In an endothermic reaction, the enthalpy change is positive because energy is absorbed from the surroundings. On the other hand, in an exothermic reaction, the enthalpy change is negative because energy is released to the surroundings. To find the total change in enthalpy based on a potential energy diagram, you would compare the potential energy of the reactants to the potential energy of the products.

Answer 2

1) Identify the axes.

The Y-axis refers to the energy in the reactants and in the products,

The X-axis refers to the progress of the reaction.

2) Important points in the diagram.

A: Potential energy in the reactants.

B: Activation energy. The energy that must be provided so the reaction occurs.

C: Potential energy in the products.

3) Enthalpy change calculation.

We calculate the enthalpy change using the following calculation:

`\Delta H=\Sigma n\Delta H_((reactants))-\Sigma n\Delta H_((products))`

4) Analysis.

If the potential energy is higher in the reactants, the enthalpy change is positive. This means the reaction is exothermic.

If the potential energy is higher in the products, the energy change is negative. This means the reaction is endothermic.

5) Diagram

The red circle marks the potential energy in the reactants and it is higher than the potential energy in the products (blue circle).

This diagram represents a positive enthalpy change.

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