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1) To find the change in enthalpy, determine the difference between the potential energy of the products and the potential energy of the reactants. (on this diagram, C-A) To find the activation energy, find the difference between the potential energy of the reactants and the "peak" of the curve (on this diagram, B-A). For this diagram, both the enthalpy and activation energy are positive.
2) If the reaction was exothermic, enthalpy would be negative, and the potential energy of the reactants would be greater than the potential energy of the products.
The Blood Alcohol Level (BAC) will rise. Because it usually peaks about 30 minutes after drinking, a sharp spike at 20 minutes makes sense.
BAC.
Explanation:
- Evaporation is defined as a process in which liquid state of water is changing into vapor state.
So, we need to break the bonds of liquid substance in order to convert it into vapor state. And, energy is absorbed for breaking of bonds which means that evaporation is an endothermic process.
Hence, the statement evaporation of water is an exothermic process is false.
- When a hydrocarbon reacts with oxygen and leads to the formation of carbon dioxide and water then this type of reaction is known as combustion reaction.
A combustion reaction will always release heat energy. Hence, combustion reaction is exothermic in nature.
- When energy is transferred as heat from the surroundings to the system then it means energy is being absorbed by the system. And, absorption of heat is an endothermic process for which
is positive.
- Whereas when energy is transferred from system to the surrounding then it means energy is released by the system which is an exothermic process.
Hence, for an exothermic process value of
is negative.
Thus, we can conclude that statements which are true are as follows.
- A combustion reaction is exothermic.
- When energy is transferred as heat from the system to the surroundings,
is negative.
- For an endothermic reaction Deta H is positive.