Discussion Topic
Heat and temperature are often used interchangeably in everyday life. It won't come as a surprise to anyone that when you increase the heat of an object, the temperature will go up. But do heat and temperature really mean the same thing? Should the terms be used interchangeably?
We have introduced the concept of heat energy. Heat is the energy that flows into or out of a system because of a difference in temperature between the system and the surroundings. Heat always flows from a hot object to a cooler object. Heat transfer occurs until all objects are the same temperature. If a hot object is put in surroundings that are the same temperature, no heat energy flows, because there is no temperature gradient.
The temperature of an object is due to the internal kinetic energy of the particles in it. When heat flows from a hot object to a cooler object, the particles within the hot object slow down. This means the object's kinetic energy decreases. So temperature reflects the amount of heat energy in the system.
One striking difference between heat energy and temperature is their dependence on the amount of substance in the system. The amount of heat energy required to change the temperature of a substance depends on the amount of substance in the system. Imagine you have a 100 gram sample of pure water at 50
C which has a heat energy of q. If you divide the water into two equal portions, what will the temperature and heat energy of each of the portions be? Consider the definitions of heat and temperature as you formulate your answer, then go online to share your ideas with your classmates.
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Joshua Dos Santos
ReplyDeleteThe temperature will be the same in both of the samples but the heat energy will be half of what it originally was in each sample.
The temperature stays the same because only half of the original heat energy is required to maintain the temperature of half the amount of the substance. Because the substance was divided in half and heat is distributed evenly, the temperature will be the same.
However, the amount of heat energy total will be only half as much in the new sample. It is still enough to maintain that temperature for the new, smaller sample, but it is half the amount of heat that existed in the original.
Andrew Park
ReplyDeleteWell, if the 100 grams of the original sample is split into two separate portions, the portions will have the same temperature, which is 50 degrees Celsius, but they will have half of the energy that was needed in the initial sample.
The reason why the heat energy would be half of the initial sample is because there is only half of the original mass in each of the two portions. Thus, it only takes half of the energy to heat the two portions to 50 degrees Celsius
Andrew Park
ReplyDeleteI agree with everything josh said because the answer for this question should be basically the same...so to liven things up, I'll ask a question. Would the same thing that happened with the water happen with a solution that was other than water, such as gatorade?
Josh Dos Santos
ReplyDeleteYes! Someone else commented!
HMmmmm uhh I'd say that with gatorade it would be the same deal. The temperature would not change, but the amount of heat energy would be half. I think that this is true for any homogenous solution.
But what about a heterogenous mixture?
heterogeneous*
ReplyDeleteMegan Dickson
ReplyDeleteThe temperature in each of the samples formed will be the same. On the other hand, the heat energy will change. If the sample was divided into two, the heat energy in each sample will be half of what it was before.
The reason for the tempertaure remaining the same but the heat energy chaning is that with half as much substance, it takes half as much energy to reach a particular point. It can be related to pushing a ball up a hill. If you are pushing a weight up a hill that weighs 100 kg, but then you divide the weight into two 50 kg samples, it will take about half as much energy to push a 50 kg weight up a hill as it would to push a 100 kg weight. The same is for heat energy.
The same goal is reached, but with less substance so it requires less heat energy.
Megan Dickson
ReplyDeleteAndy: Yes, you are certainly right. When you have half of the mass of an orginal sample of a substance, it only requires half of the energy to heat it to a 50 degress Celcius.
It can all be understand with principles of algebra :)
Dwayne Hahm
ReplyDeleteThe temperatures for these two samples are same, but the heat energy is different. The reason is the heat energy matters with the mass of the substance, but temperature is the characteristic of the substance that does not change in mass. The 100 grams of the sample will need twice times of the heat energy than 50 grams of the sample.
Dwayne Hahm
ReplyDeleteThanks Megan.
Your example really helped me to understand the difference between the temperature and the heat enegy.
Esther Lee
ReplyDeleteAccording to definition, 'the amount of heat energy required to change the temperature of a substance depends on the amount of substance in the system.'
When you divide 100 gram sample of pure water into two equal portions, the temperature will be same for both(50'C). However, since the amount of water decreases, its heat energy required to change the temperature for 50'C sample decreases.
Esther Lee
ReplyDeleteJosh) I think same process is applied for heterogenous solution because the system(heterogenous solution) does not change its substances and its heat capacity. When you divide heterogenous solution into two equal portion, the temperature will be the same but the amount will be decreased. Therefore, the amount of heat energy required to change the temperature of divided solution will be decreased.
Moon Kyu Kim
ReplyDeleteThe temperature of each portion will remain same, but the heat energy will be decreased into half of its original 100g. The reason is that the temprature and heat do not mean same thing. The heat energy is required to heat up the certain amount of the substance. Since the heat energy depends on the amount of the substance, divided water will need less heat energy to maintain 50'C.
So, it has only half amount of heat energy.
I feel like I am just repeating but I suppose I have no choice. Sorry bout the lateness, the blog wouldn't let me on for some reason.
ReplyDeleteWell as stated before me, temperature remains the same in both halves of the split substance since that does not depend on the size of amount of matter of the substance but rather it is the measure of the movement of the particles that make the substance up so even if there were less particles, or molecules, sorry, they would still be moving the same as they were before.
The substance will have half the amount of heat energy due to it's dependance on the amount of matter or substance.
-Allie VanO
Well, I'm not sure how to respond to any of you, but I suppose I can focus on the example stated before by Josh and Andrew with the gatorade, we mentioned another liquid but what about a solid, or a gas? Would the same rules still apply?
ReplyDeleteAllie VanO
Ellen Cho
ReplyDeleteThe temperature of the water will remain equal as 50 degrees celsius, but the heat energy will be divided into half to each portion. The temperature is just a measurement of hot and cold that it will not change even if the water is divided since the water feels same after it is divided. However, the heat is the energy that flows into or out of a system, if the water is divided, since the mass is divided into half, the energy will also divide into half.
Ellen Cho
ReplyDeleteMegan:Your example was great to understand the concept heat energy easily. I also agree with everyone since it seems everyone has same answer for this question.
Haily Oh
ReplyDeleteI think even though it is saparted, the temperature would be constant.Therefore, the temperature of the water would be 50 celcius. However, the heat energy would be divded into two because if the volume of water increases, the heat energy would increases. That follows same here.
Megan's example of pushing a ball helps me to understand better.Also it is great that most of us came up with same answers!
ReplyDeleteDang i'm late....
ReplyDeleteUmm, Okay, so this was actually in our online lecture. The lecture stated that the temperature of the two portions of water would be the same as the original water, but that the heat energy would be different in proportion to the original one. So the half the water of the original will have half the heat energy of the original water.
To maintain certain temperature, the amount of heat proportionate to the mass of the substance is required to keep the temperature same. Which, in other words, means that only half the heat energy is required to maintain the temperature.
In short, since mass and heat energy is proportionate to each other, it is just simple math that one needs to do.
Ehh, it seems like someone has already answered andrew's question, but let me just say it again.
ReplyDeleteThe amount of energy required to raise or keep the temperature of the gatorade will be different from the amount of energy needed for water, because it's specific heat capacity will differ. However, it would not change the fact that you only need half the amount of energy with half the amount of original, because heat energy is relative to the mass than temperature....
Good question that you brought up XD
Nice job, andrew