Calculate Heat of Reaction for 50g of Water at 80°C

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Discussion Overview

The discussion revolves around calculating the heat absorbed by room temperature water when mixed with hot water. Participants are exploring the application of the heat transfer equation in a scenario involving two bodies of water at different temperatures. The focus is on understanding the correct mass to use in the calculations.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant proposes using the equation Q = mc(dT) to calculate the heat absorbed, questioning whether to use 50g or 100g as the mass.
  • Several participants clarify that there is 50g of room temperature water, suggesting that this is the mass to use in the heat calculation.
  • Another participant emphasizes that the situation is straightforward, indicating that the mass of the room temperature water is clearly 50g.
  • One participant introduces a hypothetical scenario where the water is isolated but still exchanges heat, reinforcing the idea that only the 50g of room temperature water is absorbing heat.

Areas of Agreement / Disagreement

Participants generally agree that the mass of the room temperature water is 50g. However, there is some confusion regarding the application of the heat transfer equation, leading to repeated questions about which mass to use.

Contextual Notes

There is some ambiguity regarding the application of the heat transfer equation, particularly in how participants interpret the mass involved in the calculation. The discussion does not resolve the confusion fully.

aDVnatgae
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Homework Statement


Hi
Lets say I heat 50g of water to 80°C. I take another 50g of room temperature water and put it in a bowl.

Then I add this 50g of heat water to the bowl, the temperature in the bowl goes from 25°C to 48°C.

What is the amount of heat absorbed by the room temperature water?


Homework Equations



Is it
Q = (50g)(4.18 J/(g*k))(48-25)
or
Q = (100g)(4.18 J/(g*k))(48-25)

The Attempt at a Solution



Do you add the solution of water in the mass or just use 50g=mass in the equation?
 
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aDVnatgae said:
What is the amount of heat absorbed by the room temperature water?

What is the mass of the room temperature water? 50g or 100g?
 
Borek said:
What is the mass of the room temperature water? 50g or 100g?

I add the 50g of hot water to 50g of water in the bowl. Wondering when calculation the
Q=mc(dT)
should the mass be 100 or 50
 
You have 50 g of the room temperature water and 50 g of hot water. What is the mass of the room temperature water?

This is like one of those stupid joke questions kids ask - answer is so obvious nobody sees it.

Yes, it is THAT simple.
 
Borek said:
You have 50 g of the room temperature water and 50 g of hot water. What is the mass of the room temperature water?

This is like one of those stupid joke questions kids ask - answer is so obvious nobody sees it.

Yes, it is THAT simple.

What is the mass of the room temperature water?
answer is 50g
 
Borek said:
You have 50 g of the room temperature water and 50 g of hot water. What is the mass of the room temperature water?

This is like one of those stupid joke questions kids ask - answer is so obvious nobody sees it.

Yes, it is THAT simple.

K. What I am asking to you is when I add hot water in the bowl to temperature of bowl changes from 25°C to 48°C. The total mass of water in the bowl is 100g.

What is the amount of heat absorbed by the room temperature water?
So do I use 50g or 100g as a mass?
 
There is 50 g of the room temperature water, so 50 g of the room temperature water can absorb a heat.

Imagine you have not mixed these samples of water, but they were isolated by a thin metal sheet so that they could not mix, but the heat could easily flow. Final temperature is identical in both cases, but it should be obvious why there is 50 g of the room temperature water absorbing heat.

Note that so far we were all the time discussing exactly the same problem, you just couldn't make a connection. If there is 50 g of the room temperature water there is 50 g of water that can absorb heat.
 

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