FAQ: Which one of the following is always positive when a spontaneous process occurs?

Which of these must be positive for a spontaneous process?

Hence, ΔStotal is positive for spontaneous reaction.

What always increases in a spontaneous process?

The second law of thermodynamics states that the total entropy of the universe always increases for a spontaneous process. The second law of thermodynamics states that the total entropy of the universe always increases for a spontaneous process.

What is true about a spontaneous process?

A spontaneous process is one that occurs on its own, without any energy input from the outside. For example, a ball will roll down an incline; water will flow downhill; ice will melt into water; radioisotopes will decay; and iron will rust.

Which process is always spontaneous?

When ΔS > 0 and ΔH < 0, the process is always spontaneous as written. When ΔS < 0 and ΔH > 0, the process is never spontaneous, but the reverse process is always spontaneous. When ΔS > 0 and ΔH > 0, the process will be spontaneous at high temperatures and non-spontaneous at low temperatures.

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Which is true for spontaneous change?

Key Concepts and Summary. The second law of thermodynamics states that a spontaneous process increases the entropy of the universe, Suniv > 0. A negative value for ΔG indicates a spontaneous process; a positive ΔG indicates a nonspontaneous process; and a ΔG of zero indicates that the system is at equilibrium.

Can a reaction be spontaneous in both directions?

All reactions occur spontaneously all the time, and their backward reactions too. If left alone for long enough, a system will eventually reach the point where the forward and backward reactions go at the same rate (and it’s not like they both stop altogether!) – that’s an equilibrium.

What is meant by a spontaneous process?

A spontaneous process is capable of proceeding in a given direction without needing to be driven by an outside source of energy. An endergonic reaction (also called a nonspontaneous reaction) is a chemical reaction in which the standard change in free energy is positive and energy is absorbed.

How do you know if a process is spontaneous without using calculations?

By considering these two factors, we come up with the Gibbs Free Energy equation to predict if a reaction will proceed spontaneously or not. If the Gibbs Free Energy is negative, then the reaction is spontaneous, and if it is positive, then it is nonspontaneous.

Do all spontaneous processes increase entropy?

These results lead to a profound statement regarding the relation between entropy and spontaneity known as the second law of thermodynamics: all spontaneous changes cause an increase in the entropy of the universe. All spontaneous changes cause an increase in the entropy of the universe, i.e., ΔSuniv>0.

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What factors make a process spontaneous?

There are two factors that determine if a process will be spontaneous or not: Enthalpy- Reactions that give off energy tend to be spontaneous. Entropy- Entropy is a measure of the randomness or disorder in a system. Generally reactions that increase the randomness of the system are spontaneous.

What is an example of a spontaneous reaction?

A roaring bonfire is an example of a spontaneous reaction, since it is exothermic (there is a decrease in the energy of the system as energy is released to the surroundings as heat). The products of a fire are composed partly of gases such as carbon dioxide and water vapor.

Why is diffusion a spontaneous process?

Diffusion is a spontaneous process since one solute is independent of the concentration gradients of other solutes and because it involves a passive transport process, which implies that energy is not expended when substances diffuse down their concentration gradient.

Which is not a spontaneous process?

Therefore, flow of heat from a cold body to a hot body is a non-spontaneous process as it requires external work as per Clausius.

Are all irreversible processes spontaneous?

Irreversible processes cannot be undone by exactly reversing the change to the system. Spontaneous processes are irreversible.

Are all spontaneous processes exothermic?

All spontaneous processes are not exothermic, because it is the Gibbs Free energy that determines spontaneity, not the enthalpy. This is a very exothermic process. But it also has a negative change in entropy, because a liquid is more orderly than a gas.

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