Entropy, Enthalpy and Gibbs Free Energy

Which phase of matter has the greatest motion and least orderly arrangement?

• solid
• liquid
• gas

Tags

NGSS.MS-PS1-4

NGSS.MS-PS3-4

6.  The formation ½ A2 + 2 B2 + C --> CAB4 has an enthalpy of formation of -104 kJ and a change in entropy of -60.8 J/K at 30 °C. What is the free energy and spontaneity of the reaction?  

• -85.6 kJ, spontaneous
• -18.3 kJ, not spontaneous
• +18.3 kJ, spontaneous 
• +85.6 kJ, not spontaneous 

Tags

NGSS.HS-PS1-4

Which one of the following is always positive when a spontaneous process occurs?

• ΔH univ

• ΔH surr

• ΔS surr

• ΔS univ

• ΔS sys

ΔS will be positive for the reaction

• 2H2 (g) + O2 (g) -> 2H2O (g)

• 2NO2 (g) -> N2O4 (g)

• BaF2 (s) ->Ba2+ (aq) + 2F- (aq)

• 2Hg (l) + O2 (g) ->2HgO (s)

Tags

NGSS.HS-PS1-4

A reaction that is not spontaneous at low temperature can become spontaneous at high temperature if ΔH is __________ and ΔS is __________.

• +, +

• -, -

• +, -

• -, +

• +, 0

Which of these have a DECREASE in entropy?

• CaCO₃(s) → CaO(s) + CO₂(g)

• 2NO₂(g) → N₂O₄(g)

• 2NH₃(g) → 3H₂(g) + N₂(g)

• C₆H₆(l) → C₆H₆(g)

Tags

NGSS.HS-PS3-4

At what temperature would a given reaction become spontaneous if ΔH =+119kJ and ΔS=+263J/K.mol

• 452 K

• 2210 K

• 382 K

• 363 K

Given the change of phase:

CO₂(g) —> CO₂(s)

As CO₂(g) changes to CO₂(s), the entropy of the system

• decreases

• increases

• remains the same

Tags

NGSS.MS-PS1-4

Entropy increases from solid, liquid to gas. Why?

• Molecular disorder increases
• Molecular randomness decreases
• Molecules are more energetic
• Molecules are more reactive

Tags

NGSS.MS-PS1-4

Reactions tend to be spontaneous if they are exothermic.

• True
• False

Tags

NGSS.HS-PS1-4