Questions tagged [heat]

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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 ...
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27 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 ...
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3answers
62 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. ...
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1answer
70 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 ...
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3answers
352 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 ...
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1answer
44 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 ...
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1answer
48 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 $CaO + CO_2$ —> $...
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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 ...
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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 ...
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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 ...
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1answer
46 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, ...
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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 ...
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2answers
50 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 ...