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How If a reaction occurs at 293 K that has a change in enthalpy of plus 125 kJ and a change in entropy of plus 35 J K then is the reaction spontaneous If so why If not why not?
Wiki User
∙ 12y ago
A process will be spontaneous when the change in Gibbs free energy is negative.
The change in Gibbs free energy can be calculated from the equation:
G2 - G1 = H2 - H1 - T(S2 - S1)
where
G is Gibbs free energy
H is Enthalpy
T is absolute temperature (when T is given in Kelvin or Rankine it is an absolute temperature)
S is Entropy
In this case
H2 - H1 = 125 kJ
T = 293 K
S2 - S1 = 35 J/K = 0.035 kJ/K
so doing the math you get
G2 - G1 = 125 - 293(0.35) = 22.45 > 0 so the process is not spontaneous in the direction where enthalpy change and entropy change are being measured. The reverse process would be spontaneous.
Wiki User
∙ 12y ago
The spontaneity of a reaction is determined by Gibbs free energy (ΔG = ΔH - TΔS). In this case, the reaction would be spontaneous at 293 K if the calculated ΔG value is negative. If ΔG is negative, it means that the reaction can occur spontaneously because the increase in entropy outweighs the enthalpy change.
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What is the symbol for free-energy change?
The symbol for free-energy change is ΔG (delta G). It represents the change in Gibbs free energy during a chemical reaction, which determines whether the reaction is spontaneous or non-spontaneous.
How does the second law of thermodynamics relate to crystal formation?
The second law of thermodynamics states that in any spontaneous process, the entropy of the universe increases. In crystal formation, atoms or molecules arrange themselves into an ordered structure, reducing the overall entropy of the system. However, the formation of crystals usually involves an increase in entropy in the surrounding environment, allowing the process to be spontaneous and consistent with the second law.
What is an exergonic reaction?
An exergonic reaction is a chemical reaction that releases energy in the form of heat or light. In exergonic reactions, the products have less energy than the reactants, resulting in a net release of energy. These reactions are spontaneous and do not require an input of energy to occur.
What is true about the numerical value of the Gibbs free-energy change for a spontaneous reaction?
B
Is the gibbs free energy equation used to measure thermodynamic functions from equilibrium measurements at different temperatures?
Yes, the Gibbs free energy equation can be used to determine the thermodynamic feasibility of a reaction as well as to calculate the equilibrium constant based on measurements at different temperatures. The equation relates the change in Gibbs free energy to the change in enthalpy, entropy, and temperature.
How does the Gibbs free energy predict spontaneity?
It tells if the reaction will process spontaneously or not
What kind of enthalpy change favors a spontaneous reaction?
An exothermic reaction is a chemical reaction that releases energy in the form of heat. It favors a negative enthalpy change.
How do you determine whether a reaction is spontaneous or non spontaneous?
The first of two factors that determine whether a reaction is spontaneous or non-spontaneous is entropy. The second is energy. For a reaction to be spontaneous, it must have both of these factors.
Do chemical reactions that increase entropy tend to occur spontaneously?
Reactions that increase the randomness. Reactions that have more moles of gas on the product side than the reactant side increase entropy. Also reactions that have a positive change in spontaneity and a negative enthalpy.
True or False A large positive value of entropy tends to favor products of a chemical reaction?
True. A large positive value of entropy indicates an increase in disorder in a system, favoring products of a chemical reaction due to the higher entropy being associated with a higher number of possible microstates for the products compared to the reactants.
What kind of reaction occurs when the entropy change of an endothermic reaction is negative?
The reaction is exothermic
What is H in the equation G H TS?
The change in entropy between products and reactants in a reaction
How is enthalpy related to spontaneity of a reaction?
S > 0 contributes to spontaneity.
On what conditions does a spontaneous reaction become spontaneous?
For some non-spontaneous reactions, you can change the temperature. For other non-spontaneous reactions, there is nothing you can do to make it spontaneous. Nature favors reactions that increase a system's entropy (disorder) and nature favors reactions that are exothermic (they release enthalpy). Any reaction that does both of these things is spontaneous at all temperatures. Any reaction that does neither of these things is never spontaneous. As far as this question is concerned, the interesting reactions are endothermic reactions that increase entropy and exothermic reactions that decrease entropy. Whether these reactions are spontaneous depends on the temperature. The first variety (endothermic, increase entropy) will be spontaneous at high temperatures; the second (exothermic, decrease entropy) will be spontaneous at low temperatures. To find the temperature at which a reaction becomes spontaneous, one may apply the Gibbs equation: DG = DH - TDS where capital Ds stand for the Greek capital delta.
Is a symbol which stands for the value equal to the entirely enthalpy minus the temperature times enthropy . It can be used to determine if a reaction will take place?
The change in Gibbs Free Energy (∆Gº) predicts if a reaction is spontaneous or not. The equation for this is ∆G = ∆H - T∆S where ∆H is the change in enthalpy, T is temperature in Kelvin, and ∆S in change in entropy.
Is Delta S is the change in enthalpy a measure of randomness?
No, ΔS (change in entropy) and ΔH (change in enthalpy) are not measurements of randomness. Entropy is a measure of the disorder or randomness in a system, while enthalpy is a measure of the heat energy of a system. The change in entropy and enthalpy can be related in chemical reactions to determine the overall spontaneity of the process.
Is the entropy change increased or decreased in 2 Na 2 H2O -- 2 NaOH H2?
As the overall entropy in increased, this reaction is said to be spontaneous.
