Questions tagged [heat]

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16
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5answers
5k views

Why does temperature not increase by putting more logs into the fire

Why does temperature not increase by putting more logs into the fire ? It is a very common observation which I have seen but after some research online I found that it is not completely true. One ...
4
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4answers
506 views

Difference between temperature and heat

It is becoming very difficult for me to understand the difference between temperature and heat. About heat all I have read : Heat exchange is related to as exchange of matter + energy. Heat is ...
2
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3answers
610 views

Mathematical derivation for 1st law of thermodynamics

Mathematical derivation for 1st law of thermodynamics : What I know : 1st law of thermodynamics is known as or derived as the conservation of energy . But how are the terms U , q and W derived from ...
1
vote
3answers
64 views

Why does thermal conductivity of a pipe matter in a double pipe heat exchanger?

My understanding is that thermal conductivity is responsible for the time until something will heat up. For example, if you hold a copper bar over a candle it will quickly become hot at the other end. ...
1
vote
1answer
77 views

In case of solvation , Who converts gaseous ions to aqueous ? Why do we even have gaseous but not solid ions?

We take Nacl and dissolve it in water. There is formation of $Na^+$ and $Cl^-$ gaseous ions along with 2H+ and $Cl^{2-}$ aqueous ions. Then , Na+ is attracted towards $Cl^{2-}$ and 2H+ is attracted ...
1
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2answers
53 views

Difficulty in understanding the scenario for this Q

Q:If a closed rigid wall container filled with 20 gm of He moving at a constant speed of 10 m/sec is stopped abruptly to stand still, find the increment in temperature of this He sample. My question ...
1
vote
1answer
45 views

What does it mean by average kinetic energy of molecules as temperature?

We say kinetic of molecules as a function of temperature from the equipartition theorem. This means that more is the velocity or mass of the body , more the is the temperature. My Q is why does ...
1
vote
1answer
52 views

Difficulty in understand the meaning of standard enthalpy of formation

Standard enthalpy of formation is when one mole of compound is formed from its constituent elements. Example : $H_2$(g) + $O_2$(g) —>$ H_2O$(L). But we don’t say the same for $CaO + CO_2$ —> $...
1
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1answer
49 views

What is heat , chemical energy and thermodynamics laws restrictions

Below is a text over which I have my questions which I have written below this text: Chemical energy stored by molecules can be released as heat during chemical reactions when a fuel like methane, ...
0
votes
1answer
50 views

Why is the carrier block in a winchester rifle made of brass?

In a Winchester 1873, the carrier block is the part that moves a cartridge from the magazine up to the chamber, and that pushes the previously spent shell up out of the top of the rifle. It moves back ...
0
votes
2answers
42 views

What can you coat/seal Gallium with?

If I were to make a sculpture out of Gallium, Ga melts at about 85 °F I think, would I be able to spray it with some sort of solvent based or not solvent based coating to help prevent it from breaking ...
0
votes
1answer
30 views

Can I consider this scenario for the phase change of $H_2O_{(s)}$ to $H_2O_{(L)}$

From a particular topic : Enthalpy changes during phase transformations. It says in my textbook that standard state of a substance at a specified temperature is it’s pure form at 1 bar pressure. Let’s ...
0
votes
0answers
17 views

How to model the kinetics of a reaction while its not being stirred in a batch reactor?

lets consider the following reaction: $$ A + B \rightarrow C $$ Where the rate of reaction ($r$) can be expressed as: $$ r = k*c_a*c_b $$ Where $c_i$ is the concentration of species $i$ and $k$ is the ...
0
votes
0answers
29 views

Air-to-Water Heat Exchanger - Car radiator

I'm looking for a way to keep a liquid under 50°C. This liquid has a thermal conductivity of .1396 and a specific heat of 2.054 both at 40°C. and a constant energy source submerged in it ranging from ...
0
votes
1answer
53 views

Why ΔH has two separate equation in my textbook?

ΔQ = ΔU + Δ(PV) (First law of thermodynamics) which has the same statement as the 1st equation. $Q_p$ or ΔH= ΔU + PΔV which is the heat exchanged at constant pressure. Then why in the image above in ...
-1
votes
1answer
48 views

Minimizing home heating costs [closed]

I live in an old rental house with 12 foot ceilings and zero ceiling fans. I am trying to conserve as much energy as possible as heating costs are expensive. I have placed plastic on all of my windows ...