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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Are the native starch's structure and properties different from retrograded starch?

Starch gelatinization occurs when native starch is being expose to heat and water. Gelatinized starch then can be retrograded under cool temperature. But the structure and properties of retrograded ...
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123 views

How much heat is needed to break CO2 down to CO?

I have found that because the oxygen is double bonded to carbon, it takes about $\mathrm{1500\ ^\circ C}$ to break it down from $\ce{CO2}$ to $\ce{C}$ and $\ce{O}$. But, I am curious, would it take ...
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30 views

Denaturing of Proteins and Nucleic Acids - Effect of Temperature (Heating VS Cooling)

Heating a protein/nucleic acid will disrupt inter-molecular and intra-molecular forces in the tertiary structure. It will also interfere with the shape of the active site if the protein. Does this ...
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26 views

Calcium chloride + starch desiccant packs inside PPE for ebola workers?

(First question on stackexchange, apologies for any faux pas) Ebola workers get drenched in sweat while working inside their personal protective equipment. There's a discussion happening over on ...
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42 views

why does a glass tube show white bands after being heated with a torch?

When I use a torch to split a glass tube, there's always a hazy white band which appears. Does anyone know what the cause of this is? (FYI, it was a hydrogen-oxygen torch. The glass is fused quartz ...
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1answer
35 views

Is there a heat capacity of an object when it is melting?

Is there a heat capacity of an object when it is melting? I'm questioning it since the temperature doesn't change during phase transitions and the units of heat capacity is Joules/Kelvin.
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1answer
50 views

Finding the equilibrium temperature between two substances in a constant pressure calorimeter

I need to find the temperature two things equilibrate to in a constant pressure calorimeter given only their specific heats, masses, and starting temps. The only thing I know for specific heat is ...
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252 views

Heats of combustion and stability of rings

Can anyone explain why? If you think about it, without having the data of the heat of combustion of each type of bond, you can't really answer this question. I know that cyclopropane has a higher ...
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2answers
189 views

What happens if you autoclave HEPES?

Many molecular biology protocols advice against sterilizing HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) solutions by autoclave. Supposedly, HEPES is heat labile, and the high ...
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67 views

What chemicals are used in receipt paper?

Most "invisible inks" turn brown when heated and they take a while to transform. I would like to make (or obtain) an "ink" that responds to the heat of an iron and permanently turns black or a ...
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1answer
148 views

The difference between heat of reaction at constant pressure and that at constant volume

If supposing the kp value of a reaction is 10 Atm at 300K and 4atm at 400K. Then how can we say that the difference between the heat of reaction at constant pressure and that at constant volume is RT ...
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445 views

How much does water expand when heated, and does salt affect that?

For this question, assume all things not mentioned are perfectly controlled, all at 14.7lbs of atmospheric pressure, and water is 100% pure of anything not mentioned, with no dissolved air. Given a ...
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41 views

Why does lactulose turn dark?

Why does the standard 10gm/15ml lactulose solution turn dark when exposed to heat above 30 degrees Celsius? This is probably a simple question. It is funny that the warnings/important information on ...
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2answers
100 views

How can I find the heat that will be released in kJ per gram for the reaction of Al with Fe2O3?

Find the heat that will be released in kJ per gram when aluminium ($\ce{Al}$) reacts with $\ce{Fe2O3}$ as follows : $\ce{2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l)}$ the information given is: $\Delta H ...
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348 views

calculate the amount of energy in KJ necessary to convert 346 g of liquid water from 0 C to water vapor at 182 C

Calculate the amount of energy in $\mathrm{KJ}$ necessary to convert $346~\mathrm{g}$ of liquid water from $0~^\circ\mathrm{C}$ to water vapor at $182~^\circ\mathrm{C}$. The correct answer is ...
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74 views

What happens when we heat an atom?

Question is simple.. If we take an atom of any element and then supply heat energy to it then what will happen? Acc to me in beginning energy[quanta(due to excitement of electron and then moving ...
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61 views

Neutralisation of HCl with NaOH - generated heat and excess concentration [closed]

If you have $75\:\mathrm{mL}$ of $M(\ce{HCl}) = 4\:\mathrm{M}$ at $25\:\mathrm{^\circ C}$ and $100\:\mathrm{mL}$ of $M(\ce{NaOH})=5\:\mathrm{M}$ at $27\:\mathrm{^\circ C}$ with a final temperature ...
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1answer
28 views

Heating of Enamel coated cooking utensils and health hazards

I've tried to research about the issue of health concerns about enamel coating of cooking utensils (i.e. dutch ovens) and failed. I should prepare a small report about the health concerns if they ...
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2answers
126 views

Does any element have nutritional (caloric) value?

Is there any single element (e.g. possibly carbon) that can be eaten, which has nutritional value in that it provides calories? I found on Wikipedia that http://en.wikipedia.org/wiki/Dietary_element ...
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32 views

Specific Heat Problem

I'm trying to figure out the formula my teacher used to come up with the answer to this question involving specific heat. The question is: The heat of vaporization for water is 540cal/1g. How many ...
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335 views

Why does diamond conduct heat better than graphite?

We were made to accept by our teachers (without any explanation) that diamond conducts heat better than graphite. What is the reason behind this behaviour of diamond.
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Suggestions for research into different fluids in heat pipes

I'm doing some research on heat pipes (check here for wiki). One of the things I'm planning to do is try some different fluids in the pipes. Water (commonly used) has a freezing point that's too high, ...
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94 views

the chemistry of fog machines?

I'm asking this in a chemistry community to learn about possible hazards. There are devices called “foggers” or “fog machines” which create vapor which appears like fog or smoke. It is used in ...
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1answer
84 views

How can I check if this mystery compound is strontium bromide?

Trying to identify a mystery compound, here are some of my notes, I'm trying to get a second opinion on what it might be! Observations Appears as a white powder, some chunks are formed, sticking to ...
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70 views

Taking Castor Oil from room temperature to 300 degrees Celsius

I am doing a project where I heat up a container (around 500ml) filed with castor oil at room temperature. I want to add a pressure/safety valve that opens up when the castor oil reaches around 300 ...
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1answer
50 views

Can water be ignited in an ozone atmosphere?

According to my calculations, the reaction $\ce{H2O + O3 -> H2O2 + O2}$ should be favourable under standard conditions. However I am told that the reaction is probably very slow in solution since ...
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71 views

Which one really determines how people feel. Heat or temperature?

We use water to cool down some machines because water has high heat capacity, which means it takes more energy to increase 1 degree. Heat transfer occurs only when temperature is different. We cool ...
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36 views

Generally available fluid with good heat transport properties

I have designed a container which is heated up and has to heat up some tube-coils of water inside of it. This container is filled with a fluid that can help store and transfer the heat received from ...
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1answer
115 views

What are the physico-chemical processes at play in ironing of clothes?

The process of ironing of clothes removes (to a large extend) the wrinkles that where introduced in the clothes while drying. Obviously this has to be some physico-chemical process that is ...
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1answer
47 views

Change in pressure or volume of molten salt

I am doing a project in which I fill a cylinder with a volume of $636cm^2$ (made of stainless steel) with molten salt: 60% Sodium Nitrate ($NaNO_3$) and 40% Potassium Nitrate($KNO_3$). The container ...
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3answers
158 views

Safety concerns - Heating PMMA (acrylic glass) and fluorinated polymers

I have some plastic optical fiber, which consists of a thin core of PMMA (polymethyl methacrylate), covered by a fluorinated polymer. I would like to heat a bundle of these fibers to ~130 degrees, in ...
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What is the heat required to melt this ice cube?

I am need of help with this question: 18 g is one mole. (a) I guess you meant to 0 degrees C? So, 70.391 x 20 = 1408 J (b) 6.01 kJ (c) 180 g is 10 moles. It would take about 15kJ to cool all of ...
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255 views

How do you calculate the total heat capacity of a reaction

I need help with this one homework question: I am combining $100\,\text{mL}$ of $0.5~\text{M}~\ce{HCl}$ and $100~\text{mL}$ of $0.5~\text{M}~\ce{NaOH}$ to obtain $200~\text{mL}$ of ...
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2answers
145 views

How to determine the vapor pressure of a glycerine and propylene glycol mixture?

I am looking to calculate the minimum heat needed to create vapor from a specific mixture. I have a mixture of 60% $\ce{C3H8O3}$ (glycerine) and 40% $\ce{C3H8O2} $ (propylene glycol, ...
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1answer
147 views

Why does glass shatter when heat is applied to it?

When I poured hot tea into a cup, the cup shattered after about three seconds. The cup was made of glass. It was pretty thin. How did the glass and the tea react in terms of chemicals. This is a bit ...
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1answer
49 views

Finding the final temperature

If $125$ Calories of heat is applied to $60.0\text{g}$ piece of copper at $21.0^\circ\text{C}$, what will the final temperature be? The specific head of copper is $0.0920 \text{ cal/gC}$. All I have ...
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2answers
108 views

Baking Soda + Oil at high temps

My mom while making Potato chips put some Baking Soda in Oil with it. Just curious to know, it was first time Baking Soda in Oil at that high temperature. Is it safe to eat? Answer ASAP before my ...
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346 views

Difficult calorimetry problems?

I figured out how to do all of the calorimetry problems except for the last few, which are the hardest of the bunch. Assume there is no heat exchanged with the environment. A. 1250 kJ of energy are ...
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1answer
76 views

general chemistry 2 heat of vaporization

Question 1. A 20.0 gram sample of n-propanal requires 9.748 kJ of heat to change from the liquid to the gas phase at its boiling point temperature. Show using these measurements a calculation of the ...
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1answer
1k views

Heat Produced when Mg is reacted with HCL

Calculate the heat produced when a strip of $\ce{Mg}$ metal with a mass of $0.0801$ gram is reacted with $50.0$ml of $1.0M$ $\ce{HCl}$ to raise the temperature of water to $7.6^\circ C$ (change in ...
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2answers
159 views

How well (or poorly) does natural leather insulate?

What is the general thermal conductivity of animal skin leather? I understand there are many different animal's skins (cow, sheep, buffalo, deer, pig), but in general, does natural leather insulate ...
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236 views

Is tea powder better dissolved when put in hot water?

I usually make tea by adding two spoons of tea powder to water at room temp. and start to heat it. My friend said it will be better to add the powder once the water starts boiling. She said that it ...
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25 views

Can you heat water with chemical additives? Would it remain safe to drink? [duplicate]

I've been wondering, is there some chemical that reacts with water, causes heat but isn't toxic?
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1answer
236 views

Determine final temperature from acid base neutralization equation and moles

50 ml of 0.2 M solution of HCl is mixed with 75 ml of 0.2 M solution of NaOH in a constant pressure calorimeter. The acid base neutralization which occurs can written as: $\ce{H+_{(aq)} + OH-_{(aq)} ...
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369 views

Is it customary to express heat loss as a negative number?

In my chemistry class, we had a problem akin to the following: If an object with mass bla and specific heat bla is placed into a bla g calorimeter with an initial temperature of bla and a specific ...
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84 views

How do I find the thermal effect of this reaction?

I have graphite turning into diamond.I need to find the thermal effect of this reaction.How would one write that?I'm not sure how to proceed here.The teacher told us to use oxygen?
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299 views

How much heat is required to dehydrate a hydrate?

If I have a hydrate, such as copper (II) sulfate pentahydrate, $\ce{CuSO_4 \cdot 5H_2O}$, what is the amount of heat to required to dehydrate it? I assume that it is equal to or greater than the ...
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2answers
222 views

Why is water evaporation not more commonly used to cool buildings [closed]

Water has a very high heat of vaporization (2260 kJ per kg). Why not just gradually sprinkle water on your roof to keep the building cool in opposed to using air conditioners? It wouldn't take much ...
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89 views

energy efficiency, transformation from chemical to thermal energy, for district heating plants

If I have a system in which I introduce 100e.u.F (energy units) derived from chemical energy (i.e. fuel) and generate thermal energy to heat water what are e.u. absorbed by water? I.e. the efficiency ...
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108 views

What is the heat energy required to perform electrolysis equivalent?

The question may be off-topic here. If my concept is flawed, please poke me in the rib (+: Sources on the internet indicate a minimum 1.2Volts is adequate for electrolysis of water; nominally 6V. ...