Entropy

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

Which represents a decrease in entropy?

• sublimation of CO₂

• boiling water

• condensation of steam on cold glass

• NaCl dissolving in water

Systems in nature tend to undergo changes toward

• lower energy and less disorder

• lower energy and more disorder

• higher energy and less disorder

• higher energy and more disorder

Tags

NGSS.HS-PS3-4

Which sample has the lowest entropy?

HINT - Look at the phase of each chemical....

• 1 mole of KNO₃(l)

• 1 mole of KNO₃(s)

• 1 mole of H₂O(l)

• 1 mole of H₂O(g)

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

• solid
• liquid
• gas

Which phase change represents a decrease in entropy?

• solid to liquid

• gas to liquid

• liquid to gas

• solid to gas

What is a spontaneous process ?

• slow process

• fast process

• process that needs an external intervention to occur

• process that does not need external intervention to occur / keep happening

Which of these reactions shows a DECREASE in entropy?

• CaCO₃(s) → CaO(s) + CO₂(g)

• 3O₂(g) → 2O₃(g)

• 2NH₃(g) → 3H₂(g) + N₂(g)

• C₆H₆(l) → C₆H₆(g)

Tags

NGSS.HS-PS1-4

Which combination of ΔH and ΔS NEVER has a spontaneous reaction?

• +ΔH and +ΔS

• +ΔH and -ΔS

• -ΔH and -ΔS

• -ΔH and +ΔS

Identify whether the following result in an increase or decrease in entropy:

3 moles of gas (on reactant side) --> 6 moles of gas (product)

• increase

• decrease