0
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
Add your answer:
Earn +20 pts
What is an exergonic reaction?
Exergonic reactions indicate a negative change in Gibbs free energy, which in English means that the reactions are spontaneous and do not require addition of energy. The exchange of oxygen and carbon dioxide in blood and lungs is an example. It is the concentration gradient that runs these exchanges passively, without additional energy from the cells.
What is true about the numerical value of the Gibbs free-energy change for a spontaneous reaction?
B
How does the second law of thermodynamics relate to crystal formation?
Short answer: the 2nd law of thermodynamics applies only to closed systems, and the only truly closed system is presumably the entire universe (if even that). Crystals always form in the context of a larger system providing energy, meaning that entropy increases elsewhere, proportionate to the decrease of entropy represented by the crystal formation. Here is a somewhat more in-depth answer: http://www.newton.dep.anl.gov/newton/askasci/1993/chem/CHEM047.HTM
What causes entropy to change when a solute dissolves in a solvent?
The solute becomes less ordered. (apex)
Which thermodynamic law has to do with entropy?
The second law of thermodynamics, generally stated, is that the entropy of an isolated system always increases in any natural process where change occurs. In a system at equilibrium, of course, the entropy remains constant.
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 tends to favor products of a chemical reaction. However, entropy can be offset by enthalpy; a large positive value of enthalpy tends to favor the reactants of a chemical reaction. The true measure to determine which side of a chemical reaction is favored is the change in Gibbs' free energy, which accounts for both entropy and enthalpy, as calculated by: Change in Gibbs = Change in Enthalpy - Temp in Kelvin * Change in Entropy A negative value of Gibbs free energy will always favour the products of a chemical reaction.
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, delta s is the change in entropy. Delta H is the change in enthalpy, the amount of heat used in a system. Entropy and enthalpy are different, but closely related.
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.
