Chemical Reactions and Gibbs Free Energy

What does Gibbs free energy indicate about a chemical reaction?

• The speed at which a reaction occurs

• The amount of energy absorbed by the reaction

• Whether a reaction will occur spontaneously or not

• The temperature at which a reaction will occur

What is the formula for calculating Gibbs free energy (ΔG)?

• ΔG = ΔH + TΔS

• ΔG = ΔH - TΔS

• ΔG = ΔS - TΔH

• ΔG = TΔH - ΔS

In the formula ΔG = ΔH - TΔS, what does 'T' represent?

• Time

• Total energy

• Temperature in Kelvin

• Transition state

Why must ΔS be converted when calculating ΔG?

• ΔG is measured in kJ and ΔS is initially in J

• ΔG is measured in J and ΔS is initially in kJ

• ΔG and ΔS are both measured in J, but in different forms

• There is no need for conversion; ΔS is already in the correct units

What type of reaction is characterized by a negative ΔG and is spontaneous?

• Endergonic reaction

• Exergonic reaction

• Equilibrium reaction

• Reversible reaction

What does a positive ΔG indicate about a chemical reaction?

• The reaction is at equilibrium

• The reaction is spontaneous

• The reaction is nonspontaneous

• The reaction releases energy

What is the formula for calculating the change in Gibbs free energy (ΔG) in a chemical reaction?

• ΔG = ΔH + TΔS

• ΔG = ΔH - TΔS

• ΔG = ΔS - TΔH

• ΔG = TΔH - ΔS

If a system has a positive change in entropy (ΔS) and a negative change in enthalpy (ΔH), what can be inferred about the spontaneity of the reaction at all temperatures?

• The reaction is non-spontaneous at all temperatures.

• The reaction is spontaneous at all temperatures.

• The reaction is spontaneous only at high temperatures.

• The reaction is spontaneous only at low temperatures.

What is the effect on the spontaneity of a reaction if the system has a negative change in entropy (ΔS) and a positive change in enthalpy (ΔH)?

• The reaction is spontaneous at all temperatures.

• The reaction is non-spontaneous at all temperatures.

• The reaction is spontaneous only at high temperatures.

• The reaction is spontaneous only at low temperatures.

Under what condition do endothermic reactions occur spontaneously?

• When ΔH is large and positive

• When TΔS is large

• When ΔH is small and negative

• When TΔS is small