Calculating change in entropy with °C or K.

In summary, to calculate change in entropy with degrees Celsius, you can use the formula ΔS = Q/T, where ΔS is the change in entropy, Q is the heat transferred, and T is the temperature in degrees Celsius. You can also use Kelvin instead of degrees Celsius, as the formula remains the same but the temperature must be in Kelvin. It is important to use absolute temperature, such as Kelvin, in calculating change in entropy because it takes into account the molecular motion of a substance, allowing for a more accurate calculation. The change in heat, Q, is directly proportional to the change in entropy, ΔS, meaning that as the amount of heat transferred increases, the change in entropy also increases. Additionally, the change in entropy
  • #1
rmiller70015
110
1

Homework Statement

[/B]
I was given a graph in the PV plane of a cyclic process and asked to find some quantities, one of them is the change in entropy for the system. I just had a question about the units.

Homework Equations


dS = CVln(Tf/Ti)

The Attempt at a Solution


The data was given in Celsius, should I convert to kelvin when I put it into this equation?
 
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  • #2
rmiller70015 said:
should I convert to kelvin
Absolutely.:wink:
 
  • #3
The only time you can use °C is when you calculate a ΔT.
 
  • #4
Thank you everyone.
 

Related to Calculating change in entropy with °C or K.

1. How do I calculate change in entropy with degrees Celsius?

To calculate change in entropy with degrees Celsius, you can use the formula ΔS = Q/T, where ΔS is the change in entropy, Q is the heat transferred, and T is the temperature in degrees Celsius.

2. Can I use Kelvin instead of degrees Celsius to calculate change in entropy?

Yes, you can use Kelvin instead of degrees Celsius to calculate change in entropy. The formula remains the same, ΔS = Q/T, but the temperature must be in Kelvin.

3. What is the importance of using absolute temperature in calculating change in entropy?

Absolute temperature, such as Kelvin, is important in calculating change in entropy because it takes into account the molecular motion of a substance. This allows for a more accurate calculation of entropy since it is directly related to the randomness of molecular motion.

4. How does the change in heat affect the change in entropy?

The change in heat, Q, is directly proportional to the change in entropy, ΔS. This means that as the amount of heat transferred increases, the change in entropy also increases.

5. Can I use the change in entropy to predict the direction of a spontaneous process?

Yes, the change in entropy can be used to predict the direction of a spontaneous process. A positive change in entropy indicates an increase in disorder, and a negative change in entropy indicates a decrease in disorder. In a spontaneous process, the change in entropy is always positive.

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