Predicting Changes in Entropy

What is the symbol for entropy?

• H

• G

• S

• E

Which represents a decrease in entropy?

• sublimation of CO₂

• boiling water

• condensation of steam on cold glass

• NaCl dissolving in water

Which represents a -ΔS?

• ice melting

• salt dissolving

• water heating up

• none of these

Which of the following scenarios describes a process with a negative entropy change?

• Building a skyscraper

• A clean room becomes cluttered

• An igloo melting

• Osmosis (I hope you know your Biology!)

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)

The entropy will usually increase when

• a molecule is broken into two or more smaller molecules

• a reaction occurs that results in an increase in the number of moles of gas

• a solid changes to a liquid

• all of these

Which combination of ΔH and ΔS always has a spontaneous reaction?

• +ΔH and +ΔS

• +ΔH and -ΔS

• -ΔH and -ΔS

• -ΔH and +ΔS

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

• +ΔH and +ΔS

• +ΔH and -ΔS

• -ΔH and -ΔS

• -ΔH and +ΔS

Ammonium nitrate dissolves in water. It is a spontaneous endothermic process because the system undergoes....

• a decrease in enthalpy

• an increase in entropy

• an increase in enthalpy

• a decrease in entropy

Tags

NGSS.HS-PS1-4

Which has a +ΔS _(system)?

• AgNO₃(aq) + NaCl(aq) → AgCl(s) + NaNO₃(aq)

• H₂O(g) + CO₂(g) → H₂CO₃(aq)

• H₂(g) + I₂(g) → 2Hl(g)

• C₂H₂O₂(g) → 2CO(g) + H₂(g)