Heat is a form to transfer energy from one body to another or from one body to its surroundings. It is closely connected to thermodynamics, enthalpy, free energy, change in the state of matter, temperature.

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Problems with calorimetry

So, I just learned about calorimetry and am doing an equation to find the amount of heat released when carbon reacts with hydrogen to form methane. The equation I am using is $$ΔH=smΔt$$ I have m and ...
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How to calculate enthalpy change of neutralisation - what mass?

How to calculate enthalpy change of neutralisation - what mass? I made an experiment where I reacted 100ml HCL 2M with 100ml NaOH 2M in 1300ml Water, and got a temperature change dT. My question is ...
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40 views

Which is the specific heat of human body?

I'm studying about heat transfer and I wanted to know if there exists a specific heat of the human body or how one studies the human body's heat transfer.
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62 views

Heat transfer of sodium sulfate decahydrate assuming complete reaction [closed]

To make use of ionic hydrates for storing solar energy you place 136 kg of sodium sulfate decahydrate on your house roof. Assuming complete reaction and 100% efficiency of heat transfer, how much heat ...
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31 views

What temperature is required to burn graphite?

I tried to burn a bunch of 8B pencil lead in a gas flame the other day. None of it actually caught fire, but being made of carbon (in the form of graphite) should cause it to burn, as graphite is ...
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22 views

Why are hydrogenation reactions exothermic?

I learnt that all reactions that yield hydrogen are endothermic (such has reforming) and reactions, that use up hydrogen, are exothermic (FCC cracking, hydrogenation, etc.). But why is this so? I know ...
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36 views

Resultant temperature of mixture

**Question: ** There are 2 flasks of equal volume, connected by a narrow tube of negligible volume, filled with nitrogen gas. When both are immersed in boiling water, the gas pressure inside the ...
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1answer
25 views

Positive vs. negative heat of solution confusion

Given that I have absolutely zero formal (or informal) education in chemistry (sorry about that), I'm struggling to get my head around what appears to be repeated confusions of the term "heat of ...
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46 views

What is the meaning when it is said “Temperature of an Oxyacetylene Torch is 3500 degrees Celsius”?

I don't think flame is anything but the product at that temperature but I am not sure. What exactly is flame? And I think the correct statement should be that the exothermic reaction here produces ...
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19 views

Estimate inflammability of ABS?

I am studying some electrical components and particularly Raspberry Pi 2 official cases. Their manufacturer says that they consists of ABS (Acrylonitrile butadiene styrene) when I ask if their ...
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1answer
71 views

Heat of combustion of stereoisomers of 1-tert-butyl-2,4-dimethylcyclohexane

Which of the compounds below has the smallest heat of combustion? I know that the heat of combustion is indirectly proportional to the stability of a molecule. And here both $\ce{CH3}$ and ...
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1answer
81 views

Calculating Final Temperature and Volume of Adiabatic Expansion

A $\mathrm{5.00\ L}$ sample of $\ce{CO2}$ at $800 \ \mathrm{kPa}$ underwent a one-step (irreversible) adiabatic expansion against a constant external pressure of $100\ \mathrm{kPa}$. The initial ...
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40 views

Calculating entropy change of surroundings

I have seen many similar questions but have not found my answer. Why do we use the actual heat involved in the process to calculate entropy change of surrounding? The only answer I can think of is ...
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43 views

Product of lead and tin alloying

It is common knowledge that tin melts at $449.5~\rm^{\circ}F$ and Lead at $621.5\rm~^\circ F$, and that when these are melted together you simply have an alloy. What happens, or what product occurs, ...
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34 views

Hess' Law, Finding Heat of Solution

I am taking an online Physical Science 20 course and my teacher enjoys throwing labs on me before explaining the actual unit. I am given these two following reactions: ...
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1answer
87 views

How to calculate the heat released when Sodium Hydroxide is dissolved in Hydrochloric acid solution?

I need to understand how to calculate the heat released when sodium hydroxide is dissolved in hydrochloric acid solution. Here is the data I gathered from a lab experiment: $50\ \mathrm{mL}$ of ...
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2answers
54 views

How can the thermal conductivity of a binary gas mixture be estimated?

Recently, I am seeking for a simple but relatively accurate method to estimate the thermal conductivity of a binary gas mixture, say ethanol vapor + nitrogen. I assume the mixture as ideal gas. The ...
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31 views

Heat capacity during state change

I read that the heat capacity of water when it is at 100 °C or 0 °C is infinite because all the heat given to it will not be used to increase temperature but to change the state. I am unable to ...
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150 views

Does Gibbs free energy of formation always equal zero for elements in standard state?

I was looking through the appendix in my chemistry textbook when I noticed that every compound that had a $\Delta H_f$ of zero also had a $\Delta G_f$ of zero. So of course the compounds that have a ...
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1answer
31 views

Heating paper to a yellowish smoke

I put some papers into a biscuit tin and put it over fire and baked it. Then I made a small hole at the top and saw yellowish smoke coming out. Any idea what the smoke could be?
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1answer
45 views

Why can mercury oxide be decomposed into mercury and oxygen upon heating?

As I am a grade 9 student, please use simple English that does not involve many technical words in Chemistry. Thank you. I have learnt from my teachers' handout that physical methods of separation ...
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1answer
74 views

Do I need to include lattice energy when calculating the energy required to vaporize NaCl?

I understand that the lattice energy is the energy released when a crystal forms and that's the reason it takes the negative sign. But do we need to add this energy again when we are trying to ...
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1answer
44 views

Difference between thermodynamic terms heat and enthalphy [closed]

What is the difference between heat and enthalphy?
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2answers
32 views

Which phase is more efficient for temperature changes?

In the case of attempting to heat and cool down an object of different states, if you in some case managed to achieve the same temperature of a solid, liquid and gas what state would scientifically ...
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24 views

Entropy change of surroundings

The entropy change of a system is given by $dS=\frac{dq_{rev}}{T}$, which at constant temperature is $\Delta S=\frac{q_{rev}}{T}$. I also learned that the entropy change of the surroundings is $\Delta ...
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1answer
68 views

Irreversible process (Isothermal and Adiabatic)

How exactly would we define an irreversible change for an isothermal process? Why can we say what the external pressure will remain constant? Please give an example. Also, why can we not define both ...
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1answer
49 views

Difference between calcination and pyrolysis

What is the difference between calcination and pyrolysis? I have polymeric materials in mind specifically I understand they both involve heat treatment but each under a different type of atmosphere, ...
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1answer
51 views

Problem on determining the Calorimeter Constant from its heat capacity

A bomb calorimeter contains $600\;\mathrm{mL}$ of water. The calorimeter is calibrated electrically. The heat capacity of the calorimeter is $785\;\mathrm{J\,K^{-1}}$. The calorimeter ...
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Electrode/solution interface : What's the difference between the electrochemical Peltier heat and the heat caused from the overpotential?

In principle heat effects caused by the passage of an electric current might arise from: electronic peltier effect at the junction of electrode/solution level, Joule effect due to solution resistance, ...
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1answer
22 views

Spectroscopy and Excitation of Electrons

As metals are heated, they glow white and then blue. How might you explain this change in color as the temperature of the metal is increased? My answer consist of the idea that with increased thermal ...
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1answer
137 views

Calculate the mass of butane gas that would be needed to heat 724 cm³ of water from an initial temperature of 7.44 °C to 50.7 °C

The thermochemical equation for the combustion of butane is: $$\ce{2C4H10(g) + 13O2(g) -> 8CO2(g) + 10H2O(l)} , \quad\Delta H = -5748 \ \mathrm{kJ\cdot mol^{−1}}$$ So far, I've calculated the heat ...
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1answer
57 views

Calculate the amount of energy released when 500 cm³ of methane gas at STP reacts with excess air according to the equation:

$$\ce{CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l)} \qquad \Delta H = -890\ \mathrm{kJ\ mol^{−1}}$$ I am not totally sure how to work this out. What I did, though, was: $\ce{CH4}$ $M = 16\ ...
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2answers
167 views

Minimum amount of water in pressure cooker

When cooking I would like to know the minimum amount of water I can add to my 6.2 L pressure cooker, worst case, so without any food. At second ring cooking the pressure is 0.8 bar. I assume I need ...
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1k views

Burns from boiling water and steam

Why is a burn to the skin caused by steam more serious than a burn caused by the same amount of boiling water at the same temperature? The temperature is the same, which implies that the kinetic ...
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108 views

Bond Energy Calculation

Dichlorine monoxide (which has the skeleton $\ce{Cl‐O‐Cl}$) is an unstable molecule and explodes readily to form chlorine gas and oxygen gas. The heat of the reaction $\Delta ...
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82 views

How quickly will steel lose structural strength from a heat flash?

I want to know if a sustained jet fuel burn around steel has the ability to make the steel structurally unsound. It seems like any applied heat that effects steel will be a kind of "heat flash": a ...
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1answer
74 views

Is there a way to make a liquid cold by a chemical reaction?

I'm looking for a way that 2 substances make a chemical reaction that uses a lot of energy, therefor use heat, and get a substance cold. I'm thinking about a 2 chamber thermos that in the middle ...
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1answer
30 views

How to light a candle with small amounts of safe to use chemicals?

Already saw some youtube video where they lit a camp fire with glycerol and potassium permanganate and tried those but the amount of the stuff you need to create enough heat is just too much. So is ...
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3answers
538 views

How to evaluate the heat of formation with computational chemistry?

I'm sorry if this is a stupid question, but since I'm a beginner with computational chemistry, please, be patient. Let's consider the reaction of formation of water: $$\ce{1/2 O2(g) + H2(g) -> ...
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1answer
613 views

What is the difference between convection and conduction?

I was having a conversation with my dad the other day and he described something as happening due to convection, and it dawned on me that I have no real clue what the difference between and convection ...
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1answer
52 views

Does Photoelectric effect occur in a micro-oven while heating food? [closed]

Does the photoelectric effect occur while heating food on a metal plate in a microwave oven? If not, then why doesn't it occur?
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1answer
88 views

Paper Towel Soaked with Isopropanol/Water Mixture Burns without Damaging the Paper. Why?

Video: https://www.youtube.com/watch?v=_qFN1hDZwp8 If you choose not to view the video, in the first demonstration a paper towel is soaked in isopropanol. As expected, the paper towel burns. However, ...
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3answers
129 views

Mixing 1 cubic meter of HCl and NaOH: Temperature rise of a metal container?

Say I (perfectly) mix $1\ \mathrm{m^3}$ of 1 M $\ce{HCl}$ with $1\ \mathrm{m^3}$ of 1 M $\ce{NaOH}$ at standard air pressure and room temperature within a metal vessel. Heat of neutralization for ...
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1answer
48 views

What is a food-safe level of exposure of plastic containers to heat?

There are many articles about how heat can trigger the release of potentially harmful carcinogens from plastic containers into the food or liquid they contain. Specifics they fail to mention, though, ...
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0answers
9 views

Evaporating water from a combination of dietary minerals: will it work safely or react?

I've combined multiple minerals dissolved in water into a preferred ratio, but would like to evaporate some of it to heighten the concentration (let's say at 200 $^{\circ}\mathrm{C}$ in the oven). The ...
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1answer
1k views

What is Enthalpy?

At school, they teach the following two formulas: $$\Delta H = -mc\Delta T$$ and $$q= mc\Delta T$$ What i am not sure is that my teacher says that q and $\Delta H$ are the same thing but to think of q ...
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1answer
249 views

Does sodium produce water when it reacts with water?

My 10th grade chemistry book states that: "Metals react with water and produce a metal oxide and hydrogen gas. Metal oxides that are soluble in water dissolve in it to further form metal ...
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1answer
352 views

What causes the difference in heat energy released by combustion for the butanol isomers?

I am currently working on an investigation where I am burning isomers of butanol to test for the heat of combustion values to see which fuel is most efficient. The fuels I am testing are 1-butanol, ...
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Why does solvation release energy? [duplicate]

Whether dissolving acids and salts is exothermic or endothermic, depends on the lattice and solvation energy. Breaking bonds in the lattice requires energy and is endothermic - that is clear. However, ...
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3answers
160 views

How can I light a fire in this case?

Is there any gas that contains oxygen so that it doesn't require oxygen from the environment in order to burn? What I am trying to do is use LPG gas, which is fed through a pipe to a burner that is ...