Podcast
Questions and Answers
Which of the following is true about exothermic reactions?
Which of the following is true about exothermic reactions?
Which of the following is true about reactions that increase entropy?
Which of the following is true about reactions that increase entropy?
What does a negative ΔG indicate?
What does a negative ΔG indicate?
What does a positive ΔG indicate?
What does a positive ΔG indicate?
Signup and view all the answers
When is a reaction at equilibrium?
When is a reaction at equilibrium?
Signup and view all the answers
When is a reaction considered under non-standard conditions?
When is a reaction considered under non-standard conditions?
Signup and view all the answers
How does the Gibbs free energy change when the reactants are increased compared to the products?
How does the Gibbs free energy change when the reactants are increased compared to the products?
Signup and view all the answers
How does the Gibbs free energy change when the reactants are reduced compared to the products?
How does the Gibbs free energy change when the reactants are reduced compared to the products?
Signup and view all the answers
What is the rationale for why the body phosphorylates ATP as a source of energy currency?
What is the rationale for why the body phosphorylates ATP as a source of energy currency?
Signup and view all the answers
Do enzymes themselves drop the ΔG?
Do enzymes themselves drop the ΔG?
Signup and view all the answers
Which one of these is the definition of a closed system?
Which one of these is the definition of a closed system?
Signup and view all the answers
Which one of these is the definition of an open system?
Which one of these is the definition of an open system?
Signup and view all the answers
According to the first law of thermodynamics, what happens to the total amount of energy in the universe during a chemical change?
According to the first law of thermodynamics, what happens to the total amount of energy in the universe during a chemical change?
Signup and view all the answers
What does the term 'enthalpy' refer to?
What does the term 'enthalpy' refer to?
Signup and view all the answers
How is the change in enthalpy (ΔH) measured in a chemical reaction?
How is the change in enthalpy (ΔH) measured in a chemical reaction?
Signup and view all the answers
What is the ΔH value for an exothermic reaction?
What is the ΔH value for an exothermic reaction?
Signup and view all the answers
What is the ΔH value for an endothermic reaction?
What is the ΔH value for an endothermic reaction?
Signup and view all the answers
What is the ΔH value for an isothermic reaction?
What is the ΔH value for an isothermic reaction?
Signup and view all the answers
According to the second law of thermodynamics, what happens to the total entropy of the universe?
According to the second law of thermodynamics, what happens to the total entropy of the universe?
Signup and view all the answers
What does an increase in entropy (S) indicate?
What does an increase in entropy (S) indicate?
Signup and view all the answers
A positive ΔH can sometimes will cause a spontaneus reaction if ΔS is...
A positive ΔH can sometimes will cause a spontaneus reaction if ΔS is...
Signup and view all the answers
A negative ΔS can sometimes cause a spontaneous reaction if ΔH is...
A negative ΔS can sometimes cause a spontaneous reaction if ΔH is...
Signup and view all the answers
A reaction will never be spontaneous if...
A reaction will never be spontaneous if...
Signup and view all the answers
If the [Products] is higher than the [Reactants] the reaction is less likely to be..
If the [Products] is higher than the [Reactants] the reaction is less likely to be..
Signup and view all the answers
A reaction will always be spontaneous if...
A reaction will always be spontaneous if...
Signup and view all the answers
Study Notes
Exothermic Reactions
- Exothermic reactions release heat energy, resulting in an increase in temperature of the surroundings.
- Common examples include combustion reactions.
Entropy and Reactions
- Reactions that increase entropy (S) tend to disperse energy and matter, leading to a more disorderly system.
- Increasing entropy is associated with processes like mixing, phase changes from solid to liquid, or gas formation.
Gibbs Free Energy (ΔG)
- A negative ΔG indicates a spontaneous reaction, meaning it can occur without external input.
- A positive ΔG suggests a non-spontaneous reaction, requiring energy to proceed.
Reaction Equilibrium
- A reaction is at equilibrium when the rate of the forward reaction equals the rate of the reverse reaction, resulting in constant concentrations of reactants and products.
Non-Standard Conditions
- A reaction is considered under non-standard conditions when reactants and products are at concentrations other than 1 M, and/or when temperature is not 25°C or pressure is not 1 atm.
Gibbs Free Energy and Concentration Changes
- Increasing reactants compared to products typically lowers ΔG, favoring the formation of products.
- Reducing reactants compared to products raises ΔG, making the formation of products less favorable.
ATP Phosphorylation
- Phosphorylation of ATP occurs to store energy in high-energy phosphate bonds, serving as a key energy currency for cellular processes.
Enzyme Function
- Enzymes do not affect ΔG directly; they lower the activation energy, speeding up the rate of reaction without altering the energy change.
Thermodynamics Systems
- A closed system can exchange energy but not matter with its surroundings, ideal for studying changes without mass loss.
- An open system allows both energy and matter to be exchanged, typical in biological environments.
First Law of Thermodynamics
- The first law states energy is conserved; it cannot be created or destroyed, only transformed, during a chemical change.
Enthalpy (ΔH)
- Enthalpy refers to the total energy of a system, including internal energy and pressure-volume work.
- ΔH is measured by the heat absorbed or released under constant pressure during a reaction.
Enthalpy Change Values
- ΔH for exothermic reactions is negative, indicating heat is released.
- ΔH for endothermic reactions is positive, indicating heat is absorbed.
- Isothermal reactions have ΔH equal to zero, where temperature remains constant.
Second Law of Thermodynamics
- The second law states the total entropy of the universe tends to increase over time, leading systems toward disorder.
Spontaneity Conditions
- An increase in entropy (positive ΔS) can offset a positive ΔH, potentially allowing a spontaneous reaction.
- A negative ΔS with a positive ΔH can also lead to spontaneity under specific conditions.
- A reaction will never be spontaneous if both ΔH is positive and ΔS is negative.
- If product concentration exceeds reactant concentration, the reaction is less likely to proceed forward.
- A reaction will always be spontaneous if ΔG is negative.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Test your knowledge of thermodynamics and the definitions of open and closed systems with this quiz. Learn about the first law of thermodynamics and how it applies to chemical reactions.
