Thermodynamics

What if both ∆H and -T∆S are positive?

+∆H = endothermic reaction + (-T∆S) = decrease in entropy then, ∆G will be positive and the reaction will be endergonic and NOT SPONTANEOUS

What does the first law of thermodynamics states?

- in every physical or chemical change, the total amount of energy in the universe remains constant, although the form of the energy may change. - Energy can be converted from one form to another but can never be created or destroyed.

How can you applied the first law of thermodynamics to a close system?

- the total amount of energy present in all forms must be the same before and after any process or reaction occurs

How can you applied the first law of thermodynamics to an open system?

-during the course of any reaction or process, the total amount of energy that leaves the system must be exactly equal to the energy that enters the system MINUS any energy that remains behind and is therefore stored within the system This is for a cell

What if both ∆H and -T∆S are negative?

-∆H = exothermic reaction - (-T∆S) = increase in entropy Then, ∆G will be negative and the reaction will be exothermic and SPONTANEOUS

How much is 1 cal

1 cal = 4.184 J

How much energy is liberated for every glucose molecule?

686 kcal

Can a system with a Positive or a negative DeltaG can proceed?

A positive ∆G cannot proceed A negative ∆G, can proceed and is said to be thermodynamically spontaneous

What is called an event where there is an increase in G?

An endergonic reaction, consuming energy

What does a event where a decrease in G is called?

An exergonic reaction, giving off energy

Tell me the signs of H, positive, negative

Delta H can either be positive or negative POSITIVE delta H -if the heat content of the PRODUCTS is less than that of the REACTANT, H will be negative and the reaction is said to be EXOTHERMIC and heat is released. NEGATIVE delta H -If the heat content of the PRODUCT is greater than that of the REACTANTS, H will be positive and the reaction is ENDOTHERMIC, heat is absorbed.

What is Delta H in conclusion?

Delta H, value for any reaction is simply a measure of the that that is rather liberated from or taken up by the reaction as it occurs under condition of constant temperature and pressure.

What is Delta H?

DeltaH= H products - H reactants

+ ∆H

Endothermic reactions

What is entropy represented by?

Entropy is represented by S And the change in entropy is DeltaS

What happens when the heat content of the product is less than the of the reactant?

H will be negative and the reaction is said to be exothermic

What happens when the heat content of the product is greater than the of the reactant?

H will be positive and the reaction is said to be endothermic

What is heat?

Heat is energy transfer from one place to another as a result of a temperature difference between the two places. Spontaneous transfer always occurs from the hotter place to the colder place

Explain how a reaction can be endothermic?

If the heat content of the PRODUCT is greater than that of the REACTANT, H will be positive and the reaction is ENDOTHERMIC

Explain how a reaction can be exothermic?

If the heat content of the PRODUCT is less than of the REACTANT, H will be negative and the reaction is said to be exothermic and heat is realized

What happens in every spontaneous reaction in terms of ∆G and ∆S?

In every spontaneous reaction there is a DECREASE IN FREE ENERGY of the system, as well as INCREASE IN ENTROPY of the universe hence the value of G is negative for every spontaneous event

What is internal energy?

Is the total energy stored within a system E

What is the equilibrium constant?

Keq is the ratio of product concentration to reactant concentration at equilibrium K=B/A A<-->B

Keq > 1?

Products predominate over reactants at equilibrium at standard temperature, pressure and pH. Reaction goes spontaneously to the RIGHT under standard conditions

Keq < 1

Reactants predominante over products at equilibrium at standard temperature, pressure and pH Reaction goes spontaneously to the left under standard conditions

When a system is said to be in a specific state, what does it mean?

That each variable properties is held constant at a specified value. Temperature, pressure, volume

What is enthalpy?

The heat content of a system. Enthalpy is represented by an H, (H for heat)

When the delta H is negative?

The reaction is Exothermic

What type of system are cells?

They are open system

How can a system exchange energy with its surroundings?

Via Heat Work

What is free energy?

a measure of spontaneity for the system alone. Its called free energy G

What does free energy provides?

a measure of the spontaneity of a reaction based solely on the properties of the system in which the reaction is occurring. this will tell us whether a given reaction will proceed spontaneously from left to right as written

What is an open system?

can have energy added to it or removed from it

- ∆S

decrease in entropy

What is energy?

energy is not simply as the capacity to do work, but specifically as the ability to cause change.

- ∆H

exothermic reactions

positive (-T∆S)

if entropy decreases

negative (-T∆S)

if entropy increases

Explain the second law of thermodynamics?

in every physical or chemical change, the universe always tends towards greater disorder or randomness -all processes or reactions that occur spontaneously result in an increase in the total entropy of the universe. The value of S is positive for every spontaneous process o reaction

+ ∆S

increase in entropy

What is thermodynamic spontaneity??

is a measure of whether a reaction or process CAN GO but it says nothing about where it WILL GO

What is a close system?

is sealed from its environment and can neither take in nor release energy in any form

What is work?

is the use of energy to drive any process other than heat flow.

What does it mean to have an increase in entropy?

it means that there is more disorder or randomness in the universe

What happens when concentration ratio is less than Keq?

it means that there is too LITTLE product present, and the reaction will tend to proceed to the RIGHT to generate more product at the expense of the reactant.

What happens when concentration ratio is greater than Keq?

it means that there is too MUCH product present, and the reaction will tend to proceed to the LEFT to generate more reactant at the expense of the product.

Keq = 1

products and reactants are present equally at equilibrium at standard temperature, pressure, and pH reaction is at equilibrium under stander conditions

Meaning of ∆G=0?

reaction is at equilibrium under the conditions for which ∆G was calculated No work can be done nor is energy required by the reaction under the conditions for which G was calculated?

Meaning of positive ∆G?

reaction is not feasible as written under the conditions for which ∆G was calculated Energy must be supplied to drive the reaction under conditions for which ∆G was calculated (endothermic)

meaning of negative ∆G?

reaction is thermodynamically feasible as written under the conditions for which ∆G was calculated Work can be done by the reaction under the condition for which ∆G was calculated (exothermic)

What is entropy?

the disorder or randomness of the universe

What is the first law of thermodynamics?

the law of conservation of energy

What is the second law of thermodynamic?

the law of thermodynamic spontaneity

When Delta H is positive?

the reaction is Endothermic

What is the surrounding

the rest of the universe but the system

What is the system?

the restricted portion of the universe that is being considered at any given moment

Explain why is the second law of thermodynamics useful?

the second law is useful for our purposes because it allows us to predict in what direction a reaction will proceed under specified conditions, how much energy the reaction will release as it proceeds, and how the energetics of the reaction will be affected by specific changes in the condition

What is thermodynamics?

the study of energy flow and processes that convert energy from one form to another.

What is the driving for any chemical reaction?

the tendency toward equilibrium provides the driving force for every chemical reaction

What if the sign of ∆H and -T∆S are different from one another?

the ∆G value can be either positive or negative, depending on the magnitudes of the ∆H and -T∆S term.

give the me formula for ∆G

∆G = ∆H - T∆S change in free energy = change in enthalpy - (temperature * change in entropy)