Question
Select the statement(s) that are true about the enthalpy of a system. Enthalpy is measured in temperature degrees. Enthalpy is a measure of thermal energy under certain conditions. Heat is released by every reaction. Enthalpy of an isolated system is constant. For an endothermic reaction to take place, heat must be absorbed by the surroundings.
Answer
4
(197 Votes)
Arthur
Professional · Tutor for 6 years
Answer
The correct statements about the enthalpy of a system are 2 and 4.
Explanation
## Step 1: We need to evaluate each statement individually to determine if it is true or false.## Step 2: "Enthalpy is measured in temperature degrees." This statement is incorrect. Enthalpy is a measure of the total energy of a system and is typically measured in joules, not degrees of temperature.## Step 3: "Enthalpy is a measure of thermal energy under certain conditions." This statement is correct. Enthalpy is a measure of the total heat content of a system under constant pressure.## Step 4: "Heat is released by every reaction." This statement is incorrect. Not all reactions release heat. Some reactions absorb heat and are called endothermic reactions, while others release heat and are called exothermic reactions.## Step 5: "Enthalpy of an isolated system is constant." This statement is correct. In an isolated system, there is no exchange of matter or energy with the surroundings. Therefore, the total energy, including the enthalpy, remains constant.## Step 6: "For an endothermic reaction to take place, heat must be absorbed by the surroundings." This statement is incorrect. In an endothermic reaction, heat is absorbed from the surroundings, not by the surroundings.