Calculating Energy Needed for Change of Phase: Do I Need One More 'mCΔT'?

In summary, the problem is to determine the amount of heat needed to change 50.0g of water at 80.0°C to steam at 110°C. The equations used are Q = mCΔT and Q = mL. The equation set up is Q = mCΔT + mL, but there is uncertainty about whether one more mCΔT is needed to raise the steam from 100°C to 110°C. The specific heat capacity needed may differ in this case.
  • #1
AbsoluteZer0
125
1
I have been given the following problem:

How much heat is needed to change 50.0g of water at 80.0°C to steam at 110°C?

The equations that I have used are the following:


Q = mCΔT
Q = mL


I've set up my equation as such:

Q = mCΔT + mL

However, I am unsure if I should leave it as it is and solve it or if one more 'mCΔT' is needed. I've used the first mCΔT to find the energy that takes the water to 100.0°C and the latent heat of vaporization to find the energy required to change the phase to steam. Do I need one more 'mCΔT?' or do I solve it as it is? If I need to add one more, would the specific heat capacity needed differ in any way?

Thanks,
 
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  • #2
You have to raise the steam from 100 C to 110 C so you require another mCΔT.
 
  • #3
LawrenceC said:
You have to raise the steam from 100 C to 110 C so you require another mCΔT.

Thanks
 

Related to Calculating Energy Needed for Change of Phase: Do I Need One More 'mCΔT'?

1. What is energy in change of phase?

Energy in change of phase refers to the amount of energy required or released when a substance changes from one phase to another, such as from solid to liquid or from liquid to gas. This energy is known as latent heat and is necessary for the molecules of the substance to overcome the attractive forces between them and change their arrangement.

2. How does energy affect the change of phase?

Energy plays a significant role in the change of phase as it determines whether a substance will change phases or not. When energy is added to a substance, it increases the kinetic energy of its molecules, allowing them to overcome the forces holding them together and change phases. On the other hand, when energy is removed, the molecules lose kinetic energy, reducing their ability to break apart and causing the substance to change back to its previous phase.

3. What is the relationship between temperature and energy in change of phase?

Temperature and energy are directly related in the change of phase. As a substance gains energy, its temperature increases, and it changes phase from solid to liquid, and then from liquid to gas. Similarly, as energy is removed, the temperature decreases, and the substance changes phase from gas to liquid, and then from liquid to solid.

4. How does pressure affect the change of phase?

Pressure also plays a role in the change of phase. An increase in pressure can cause a substance to change from a gas to a liquid or a liquid to a solid, as molecules are forced closer together and have less space to move around. Similarly, a decrease in pressure can cause a substance to change from a liquid to a gas or a solid to a liquid, as molecules have more space to move around and can overcome the attractive forces holding them together.

5. Can energy in change of phase be measured?

Yes, energy in change of phase can be measured using a calorimeter, which is a device that measures heat changes in a substance. By measuring the temperature change of a substance during a phase change, the amount of energy required or released can be calculated using the equation Q = mcΔT, where Q is the energy, m is the mass, c is the specific heat capacity, and ΔT is the change in temperature.

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