Examples of spontaneous change in the following topics:
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- ΔG determines the direction and extent of chemical change.
- In a spontaneous change, Gibbs energy always decreases and never increases.
- $\Delta G > 0$: The reaction will occur spontaneously to the left.
- where ΔG = change in Gibbs free energy, ΔH = change in enthalpy, T = absolute temperature, and ΔS = change in entropy
- In particular, notice that in the above equation the sign of the entropy change determines whether the reaction becomes more or less spontaneous as the temperature is raised.
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- There are two types of processes (or reactions): spontaneous and non-spontaneous.
- Spontaneous changes, also called natural processes, proceed when left to themselves, and in the absence of any attempt to drive them in reverse.
- This means a release of free energy from the system corresponds to a negative change in free energy, but to a positive change for the surroundings.
- The second law of thermodynamics states that for any spontaneous process, the overall ΔS must be greater than or equal to zero; yet, spontaneous chemical reactions can result in a negative change in entropy.
- Spontaneity does not imply that the reaction proceeds with great speed.
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- In a galvanic cell, where a spontaneous redox reaction drives the cell to produce an electric potential, the change in Gibbs free energy must be negative.
- In a galvanic cell, where a spontaneous redox reaction drives the cell to produce an electric potential, the change in Gibbs free energy must be negative.
- If E°cell > 0, then the process is spontaneous (galvanic cell)
- Because the change in Gibbs free energy is negative, the redox process is spontaneous.
- Calculate the change in Gibbs free energy of an electrochemical cell, and discuss its implications for whether a redox reaction will be spontaneous
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- In the late 19th century, Josiah Willard Gibbs formulated a theory to predict whether a chemical reaction would be spontaneous based on free energy:
- Here, ΔG is the change in Gibbs free energy, T is absolute temperature, R is the gas constant, and Q is the reaction quotient.
- Gibbs' key contribution was to formalize the understanding of the effect of reactant concentration on spontaneity.
- The change in Gibbs free energy for an electrochemical cell can be related to the cell potential.
- When a change in the concentration or activity of reactants occurs, or the temperature or pressure changes, the output voltage changes.
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- Neither the relative strengths of the oxidizing or reducing agents nor the magnitude of the potential will change.
- However, what will change is the sign of the standard electrode potential.
- This means we can convert a spontaneous reaction to an unfavorable one and vice versa.
- In order to predict if two reactants will take part in a spontaneous redox reaction, it is important to know how they rank in an electrochemical series.
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- Since a business that seeks to increase its sales level will require more assets to meet that goal, some provision must be made to accommodate the change in assets .
- AFN = Projected increase in assets – spontaneous increase in liabilities – any increase in retained earnings.
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- Every chemical reaction involves a change in free energy, called delta G (∆G).
- The change in free energy can be calculated for any system that undergoes a change, such as a chemical reaction.
- This total energy change in the system is called enthalpy and is denoted as ∆H.
- These chemical reactions are called endergonic reactions; they are non-spontaneous.
- Exergonic and endergonic reactions result in changes in Gibbs free energy.
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- Stable isotopes are atoms that are not radioactive, in other words, they are not going to lose neutrons and decay spontaneously.
- This work is especially important due to our current concern with climate change/global warming.
- Elements of the same name (for example, oxygen) must always have the same number of protons, but the number of neutrons can change.
- Adding or subtracting neutrons from an atom does not change the elemental properties, but it can alter some of its features (like making it more radioactive).
- This work is especially important due to our current concern with climate change/global warming.
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- There are two types of spontaneous pneumothoraces, a primary pneumothorax and a secondary pneumothorax.
- Small spontaneous pneumothoraces typically resolve without treatment and require only monitoring.
- Primary spontaneous pneumothorax (PSP) tends to occur in young adults without underlying lung problems, and usually causes limited signs and symptoms.
- PSP occurs more commonly during changes in atmospheric pressure and during exposure to loud music.
- Secondary spontaneous pneumothorax (SSP), by definition, occurs in individuals with significant underlying lung disease.
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- Temporary dipoles are created when electrons, which are in constant movement around the nucleus, spontaneously come into close proximity.
- Although charges are usually distributed evenly between atoms in non-polar molecules, spontaneous dipoles can still occur.
- How does changing the Van der Waals attraction or charging the atoms affect the melting and boiling point of the substance?