Questions tagged [heat]

For questions about heat - a form of transfer of energy from one body to another or from one body to its surroundings. Also see these tags: [thermodynamics], [enthalpy], [energy], [temperature].

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Cinnabar decomposition by heating optional method?

Is it possible to decompose cinnabar into $\ce{Hg}$ and $\ce{S}$ instead of $\ce{Hg + SO2}$ with roasting and heating. What conditions need to be satisfied in the new method?
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In a heating curve, when it is plateau, where does all the energy go since the temperature does not get higher? [closed]

So between the change of phases within the matter(solid liquid gas), the temperature reaches a plateau, no matter how much heat you add to it, it just stays the same. Where did all those energy go?
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Why does higher temperature affect the rate of electrolysis?

I understand that more heat energy= higher rate of electrolysis, but can someone explain using higher-level terms why this occurs and if there are any theories or rules that explain this?
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What is non toxic to fish, has a low freezing point, and floats on water?

I am looking for a liquid that floats on water that will prevent the water from freezing (or at least slow it down). The application would be a small area (less than a square foot). It has to be non-...
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866 views

Why is the sum of two inexact differentials exact?

From the first law of thermodynamics, $\mathrm{d}U = đQ + đW$, where $\mathrm{d}$ represents an exact differential and $đ$ an inexact differential. Exact differentials correspond to state functions ...
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Any examples of reactions where simpler molecules are combined into more complex ones and are endothermic at the same time? [closed]

Can you name examples of reactions that are endothermic and simple molecules are combined into more complex ones at the same time? Like what plants do they take heat and sunlight and they synthetize ...
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1answer
32 views

Is incineration of a solid fuel complete or incomplete?

If I have some solid material like biomass and incinerate it at 1000 Celsius degrees for 15 minutes in an oxidized atmosphere within an incineration oven. As an output it gives me ash. Is the ...
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56 views

Why does water splash if you put it into a hot pan? [closed]

I had kept my tea pan on the stove (At high)for about 30seconds . I was making tea and getting the water to put in the tea pan. There was nothing in it before that .After that , I quickly poured some ...
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Verify heat produced by flame using enthalpy of fomation

I'm simulating using a CFD solver a pure oxygen/methane flame. However, I doubt that the combustion model does not produce enough heat. The heat from reaction is defined by $S_h=-\sum_{j} \frac{h_j^0}{...
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1answer
420 views

What factors promote honey's crystallisation?

Honey is a complex mixture containing, probably, more than hundred compounds. I understand that the % of those components will affect the crystallisation. However, I am wondering what factors may ...
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What causes little spikes in a flame? [closed]

I have a lighter at home which everytime I use it, generates little spikes (see picture below) which eventually disappear. The Spikes are not an effect generated by the camera. I can confirm that ...
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1answer
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A lot of confusion in 1st law of thermodynamics [closed]

My sir told me that Total energy of system = K.E + P.E in starting. Then Change in energy = F(External force on body ) * displacement of walls. Then from here , change in energy = W+q. (Don’t ...
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Help in understanding first way of changing the state of system

There is a statement in my book: THERMODYNAMICS One way: We do some mechanical work, say $\pu{1 kJ},$ by rotating a set of small paddles and thereby churning water. Let the new state be called $\...
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1answer
46 views

Is there an actual specific heat for aluminum in its gaseous state? [closed]

I've scourged the internet and I can't seem to find it anywhere although I've found the specific heat values for aluminum in both solid and liquid states. I'm trying to construct a heating curve and I ...
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2answers
57 views

Oxygen generator, heat driven, from air

What chemical can be used to absorb $\ce{O2}$ from the air at normal temperature and pressure, then release the $\ce{O2}$ at normal pressure and elevated temperature, below $\pu{900 ^\circ C}$ ($\pu{...
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Searching for a fireproof sponge?

(I know this is a bit off topic, but I don't know where else to ask. If you know a better StackExchange site, please tell me) I'm working on a project, and I want to basically create a "flaming ...
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1answer
60 views

How to break bonds of tea on a curtain? [closed]

If I throw tea on my curtain , it looks as if the curtain has absorbed tea molecules but is it true to say that since matter has spaces between them.So these tea molecules go into that space and stick ...
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1answer
24 views

Energy loss in the process for exothermic reactions

Some chemical reactions while producing the product molecules releases heat to the surroundings and such reactions are called “exothermic reactions”. Is it true that such systems must be showing ...
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38 views

Question to find increment in total energy of a sample of He gas? [closed]

If a closed rigid wall container filled with 20 gram of Helium gas moving at a constant speed of 10 m/sec is stopped abruptly to stand still, find the increment in temperature of this He sample. Way I ...
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115 views

How does heat transfer between molecules happen in deep?

Inside the container is cold water and outside the container is hot water. B is the microscopic view of container walls .W is water And A is hot water. What I have shown is the microscopic view of ...
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56 views

Which has more internal energy, a bucket of hot water or a bucket of cold water

Online answer I found : The bucket of hot water has more internal energy. Internal energy depends on the amount (mass) of substance and the kinetic energy of the molecules of the substance. My ...
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3answers
79 views

What is the difference between fire and warm body? [closed]

A burning body has flames (Candle flame)whereas a hot or warm body (warm utensil or body being hot but doesn’t burn )is just very hot. Keeping hand near a burning body makes you feel hot but not ...
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51 views

Does hot water dissolve Copper more than cold water?

I read from WA state dept health https://www.doh.wa.gov/portals/1/Documents/pubs/331-178.pdf that hot water disolves copper more copper than cold water. Use cold water for drinking and cooking. ...
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What is the most exothermic reaction with water? [closed]

What substance reacting with water at room temperature and atmospheric pressure produces the most heat (per mole)? Does anything beat fluoroantimonic acid?
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1answer
65 views

Thermodynamics heat, enthalpy, Gibbs

We know the basic Thermodynamic equations are: $$ dU=-PdV+ TdS + \mu dN$$ $$ dH=dU+d(PV)= TdS+ \mu dN + VdP$$ we typically assume constant Pressure for a reaction carried out in air and neglect the dP ...
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Good Hess's Law experiment [closed]

I am doing an Internal Assessment for my IB chemistry class, and I want to do something on Hess's Law, and I'll be doing it simulation based, using this website. With the solutions and equipment on ...
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99 views

Specific Heat Derivation

The specific heat capacity at constant volume and the specific heat capacity at constant pressure are intensive properties defined for pure, simple compressible substances as partial derivatives of ...
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37 views

Is heat a form of energy or is it just a transport of energy, not energy itself?

In every textbook I read, it says that heat is a form/type of energy... but in lecture, my professor said, that there is no such energy as heat and that heat is just a method by which we can transport ...
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How is pumping “Air” into a bicycle make dW (delta work )negative , when in fact there is a increase in pressure and a slight increase in volume? [closed]

Considering that it's an adiabatic process hence $\mathrm dQ=0$, and $\mathrm dU=\mathrm dW$. And since the work is done on the system then $\mathrm dW$ must be positive. (The answer which is in the ...
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Does heating potato starch destroy its resistant starch?

Resistant starch, as found in potato starch, is supposed to have health benefits. There are differing opinions on whether or not heating potato starch destroys the resistant starch in it and thereby ...
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Strange Distillation Behavior

I was attempting a fractional distillation with 1mL water and 1mL propylene glycol, and I’ve been encountering strange behavior with the heating of the mixture. The heating curve shows strange “spikes”...
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Can single molecules of C and O2 react in isolation, and if so how will momentum be conserved?

I am trying to figure out how is it possible to reconcile the reality of exothermic reactions, which means that kinetic energy is transferred to (heats) the surrounding matter, with the principle of ...
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2answers
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How does the calorimeter affect heat released by the system (q)? [closed]

Here are the 2 questions I am pondering about How would the calculated quantity of heat (q) released by a system differ if the calorimeter's heat capacity was taken into account? My thought process ...
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Does fractionation use enough heat to destroy nutrients in Coconut Oils when seperating the MCT oils?

We have recently been giving MCT (medium-chain triglyceride) oil to our dogs in place of Coconut Oil as from what I understand the majority of the benefits of Coconut Oil comes from the MCT's ...
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Can carbon dioxide be reduced to carbon monoxide and oxygen to produce energy?

There are lots of questions about reducing or burning CO2 to carbon and oxygen to solve climate change, but of course that wouldn't work because it takes a lot of energy. But carbon monoxide is more ...
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How does a change in pH affect the colour of a leuco dye in a thermal paper?

I am investigating the way that a leuco dye is released in thermal paper once heated. I have understood that leuco dyes, when in their colourless state are encapsulated in an acid developer in the ...
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38 views

Why does branching increase stability? [duplicate]

The heat of combustion of neo- pentane is lower than n-pentane.This clearly means that neo-pentane is more stable than n-pentane.What is the reason for this?
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200 views

Latent heat of vaporization/evaporation

It's the amount of heat required for liquid ---> gas phase change of a substance at it's Boiling point. But my question is, does providing energy equivalent to latent heat of vaporization to a ...
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2answers
205 views

Internal energy for Phase Transitions

Can we justify that "For sublimation of a solid at 1 atm $\Delta U>0$ at low temperature and $\Delta U<0$ at high temperature?" I read several answers and came to know that $U=f(T)$ ...
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Thermochemistry questions regarding enthalpy [closed]

I have a few questions about heat of combustion. I have two different scenarios that I was to present: Scenario 1: Given heat of combustion in the equation $\ce{CH4 + 2O2 -> CO2 + H2O}$ and $\Delta ...
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Boilling colloidal silver?

I have some colloidal silver that i bought from a shop. It is 18ppm, however, I need a higher PPM and I can't seem to buy it anywhere where I live. If I boil this colloidal silver, would it make the ...
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Re-Fusing (Unsplit) Cracked Glassware

If I heat up cracked glassware (wherein a crack has gone through part of the glass without any glass splitting away) will it cleanly refuse together before the whole piece loses its shape? If so, ...
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302 views

When can you use the direct flame of a Bunsen burner, and when must you boil a beaker of water first?

I'd like to ask when you would do the following: use the direct Bunsen flame to heat a substance; place the substance in a test tube, which is placed in a beaker of water, then boil the water with the ...
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133 views

Heat Transfer Coefficient Problem

The Problem An unusual reference gives the formula below for the heat transfer coefficient of an emulsion. $$H = 0.0061\left(X^{0.6} + 0.038T\right)\cdot V^{0.35}$$ In the formula $T$ is the ...
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How can a thermometer ever show the actual temperature of an object if the object loses heat to the thermometer?

We know that when two objects are placed in contact with each other, after a period of time, the two objects will have the same temperature. Thus, if a hot body comes into contact with a relatively ...
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Latent Heat, Vapor pressure and Equilibrium [duplicate]

So after reading about this topic i wanted to share what i learned and i wanted you guys to tell me if what i am writting is correct: A pressure vessel has propane inside and it is pressurized. The ...
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Cis-Trans Isomers Heat of Combustion

Consider the 4 cis-trans isomers for the above compound. In what way would the cis-trans isomers affect their heat of combustion. I think that if the substituents are on alternating sides of the ...
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1answer
52 views

Gibbs–Helmholtz equation

The Gibbs–Helmholtz equation was developed in the 1870's, while Nernst's heat theorem was developed in the early $20^{th}$ century (according to google/wikipedia). Nernst's heat theorem tells us that ...
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1answer
203 views

Confusion on when to use mass of entire solution when performing q=mc∆T

I hope you are having a good day. I am studying for the AP Chemistry exam in May 2020. While studying, I encountered a doubt. In Problem 1 (the question on the top), the educator saw that the ...
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Change in temperature if salt is dissolved in water with different initial temperatures

I will mix a salt with room-temperature water and 8 degree Celsius water. Then I will compare the heat of solution with each other. Does the initial temperature of the water affect how much the heat ...

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