Gibbs Free Energy

Match the ΔG values to the correct reaction description. 1) ΔG=0 2) ΔG < 0 3) ΔG > 0 A) Spontaneous B) Non-Spontaneous C) At equilibrium

1-C) ΔG=0, At equilibrium 2-A) ΔG < 0, Spontaneous 3-B) ΔG > 0 , Non-Spontaneous

What is an activation energy?

Energy needed to get a reaction started

What is the difference between Endergonic and Exergonic.

Endergonic- non-spontaneous Exergonic- spontaneous

What is the difference between enthalpy (ΔH) and entropy (Δs)?

Enthalpy- is the heat transfer in a reaction; determines exo/endo themic Entropy- is the randomness of the system

What is the difference between exothermic and endothermic reactions?

Exothermic- Heat is a product, gives off heat Endothermic- Heat is a reactant, heat needs to be put in.

True or False: All spontaneous reactions have low activation energies.

False. Activation energy is not dependent on free energy.

True or false: All spontaneous reactions will occur quickly.

False. Thermodynamics does not dictate kinematics. Spontaneous reactions could have a large activation energy that make them very slow.

What is the difference between heat and temperature?

Heat - is the amount of energy transferred Temperature- is a measure of kinetic energy of molecules

If you feel cold, are you giving off heat or are you absorbing it?

If you feel cold its because you are giving off heat.

If ΔG is greater than zero the reaction is ________ and if it is less than zero it is _________. a) spontaneous, non-spontaneous b) non-spontaneous, spontaneous c) non-spontaneous , at equilibrium d) spontaneous, at equilibrium

If ΔG is greater than zero the reaction is NON-SPONTANEOUS and if it is less than zero it is SPONTANEOUS. b)non-spontaneous, spontaneous

Gibbs Free energy

MCAT self prep

What does Gibbs free energy tell us?

Tells us whether a chemical reaction can occur spontaneously

What is Le Chatelier's principle?

The idea that if you change the conditions of a reversible reaction at equilibrium, the system will try to counteract that change

What is Hess's Law?

The total enthalpy change of a reaction is independent of the route taken.

Are spontaneous processes reversible or irreversible?

They are irreversible.

True or false: Activation energy affects how fast a reaction will proceed.

True. The lower the activation energy the faster the reaction.

Why are enzymes important?

speed up chemical reactions by lowering the activation energy.

What is the equation for Gibbs free energy?

ΔG = ΔH - TΔS

What equation do you use to find the Gibbs free energy not at standard conditions ?

ΔG=ΔG°+2.303*RT*log (Q)