Question

If a reaction is exothermic and its entropy change is positive, which statement is true? If a reaction is exothermic and its entropy change is positive, which statement is true? a. The reaction is spontaneous only at higher temperatures. b. The reaction is nonspontaneous at all temperatures. c. The reaction is spontaneous at all temperatures. d. The reaction is spontaneous only at lower temperatures.

Answer 1

The answer is C. This reaction is spontaneous at all temperatures.

Further Explanation

Heat is an energy that is easily received and easily released so that it can change the temperature of these substances into rising or falling. Heat can also move from one substance to another through a medium or intermediary. For example, two substances that have different temperatures are mixed in a container. Then the temperature of the two objects will be the same.

An endothermic reaction is a reaction that absorbs heat (there is heat transfer from the environment to the system). Endothermic reaction (endo-is a prefix meaning "inward"), where heat must be supplied to the system by the environment. In this reaction, there is heat transfer from the environment to the system so that the ambient temperature drops and becomes colder. Endothermic reactions absorb a certain amount of energy so that the energy of the system increases. Because enthalpy increases, the enthalpy change is positive. In endothermic reactions, the system absorbs energy. Therefore, the enthalpy of the system will increase. That is, the product enthalpy (Hp) is greater than the reactant enthalpy (Hr). As a result, the enthalpy change is the difference between the product enthalpy and the reactant enthalpy (Hp-Hr) which is positive. And the enthalpy changes for endothermic reactions can be stated as follows:

∆H = Hp-Hr> 0 (Positive)

Exothermic reactions are chemical reactions that produce heat. In this reaction, there is heat transfer from the system to the environment so that the environment becomes hotter. The exothermic reaction sign is a negative enthalpy change (∆H = -). This is because the exothermic reaction will release energy so that the enthalpy of the system decreases. Examples of exothermic reactions include combustion reactions, such as wood combustion, methane, propane, and the reaction between aluminum powder and iron oxide. Another example of an exothermic reaction in the manufacture of ethanol from glucose fermentation.

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definition of Heat brainly.com/question/12442928

definition of An endothermic reaction brainly.com/question/12442928

definition of Exothermic reactions brainly.com/question/12442928

Details

Grade: High School

Subject: Chemistry

keywords: Exothermic reactions, Heat

Answer 2

Answer:

• c. The reaction is spontaneous at all temperatures.

Explanation:

The spontaneity of a reaction can be determined by the thermodynamic property named Gibb's free energy or simply free energy (G).

The change in the free energy of a system is defined as the difference between the increase in enthalpy (ΔH) and the product of the temperature (T) times the increase in entropy (ΔS):

• ΔG = ΔH - T ΔS

The sign of ΔG tells if a reaction is spontaneous according to this:

• ΔG < 0, the reaction is spontaneous.

• ΔG = 0, the reaction is in equilibrium.

• ΔG > 0, the reaction is not spontaneous.

The question states that a reaction is exothermic, and its entropy change is positive. That means:

• Exhotermic: ΔH < 0
• Positive entropy change: ΔS > 0

Remember that the temperature is stated in absolute scale, so T is always positive.

Hence, ΔG = ΔH - T ΔS = (negative) - T (positive) = (negative) + (negative) = negative.

Conclusion: since ΔG is negative, regardless the temperature, you conclude that the reaction is spontaneous at all temperatures, which is the option c.