Quiz on Enthalpy and Thermodynamics

What determines whether a reaction is endothermic or exothermic?

• The color of the reactants

• The direction of energy transfer

• The size of the molecules

• The speed of the reaction

What does the standard enthalpy change, ΔH°, refer to?

• The color change in a reaction

• The heat transferred at constant pressure

• The speed of a reaction

• The volume change in a reaction

What is the relationship between bond-breaking and energy?

• Bond-breaking absorbs energy

• Bond-breaking releases energy

• Bond-breaking has no energy change

• Bond-breaking creates energy

What is the equation for calculating enthalpy change using heat capacity?

• Q = mcΔT

• ΔH = mcΔT

• Q = ΔH/n

• ΔH = Q/n

What is the purpose of a Born-Haber cycle?

• To measure temperature

• To show energy changes in ionic compound formation

• To calculate speed of reactions

• To determine color changes

What is the role of Hess's law in multi-step reactions?

• It calculates speed

• It calculates enthalpy changes

• It measures volume

• It determines color

What is the significance of potential energy profiles?

• They show color changes

• They show energy changes in reactions

• They measure speed

• They determine volume

What does entropy (S) measure in a system?

• The temperature of the system

• The pressure of the system

• The dispersal or distribution of matter and/or energy

• The volume of the system

When is a change in Gibbs energy (ΔG) considered spontaneous at constant pressure?

• When ΔG is positive

• When ΔG is zero

• When ΔG is negative

• When ΔG is constant

What happens to ΔG as a reaction approaches equilibrium?

• ΔG becomes more positive

• ΔG becomes less negative and reaches zero

• ΔG remains constant

• ΔG becomes more negative