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Part A
For each phase change, determine the sign of
and
.
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Sublimation , Freezing,Condensation, Deposition, Boiling , Melting
a) +ΔH,+ΔS
b) -ΔH, -ΔS
c) +ΔH, -ΔS
d) -ΔH, +ΔS
Put the phase change to the correctsign of ΔH and ΔS
♦ Relevant knowledge
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A phase shift can be described as positive entropy, if the substance are more able to move. For instance, a change from solid change to gas can have positive the entropy. A phase shift has positive enthalpy in case the molecules require energy to be separate. For instance, converting solids into gas is positive Enthalpy.
The ΔH energy change
The degree of randomness (change in entropy) ΔS
You will need to answer the following question: What are the signs of [katex]\Delta H[/katex]?
Sublimation – This is the process by which a substance is converted directly into a gaseous state.
Freezing – A process by which a liquid substance is transformed into a solid state is known as freezing.
Condensation is the process by which a substance that is in a gaseous state becomes liquid.
Deposition – This is the process by which a substance that is in a gaseous state is converted directly into a solid state.
Boiling is the process by which a liquid substance is transformed into a gaseous state.
Melting – This is the process by which a substance that is solid is transformed into a liquid state.
Sublimation is a positive energy change and a positive change in randomness.
The change in energy and randomness are both negative for freezing.
Condensation is characterized by a negative change in energy and a negative change in randomness.
Deposition is characterized by a negative change in energy and a negative change in randomness.
Boiling is a positive process. The change in energy and randomness are also positive.
The change in energy and randomness are both positive for melting.
Ans:
Sign of [katex]\Delta H[/katex]