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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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 ...
8
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1answer
51 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 ...
2
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1answer
75 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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198 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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1answer
33 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
24 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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1answer
82 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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2answers
45 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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0answers
39 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
22 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 ...
2
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2answers
105 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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1answer
26 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 ...
2
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1answer
72 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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0answers
13 views

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, ...
3
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2answers
80 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 ...
2
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1answer
72 views

Help identifying a compound?

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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0answers
60 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 ...
3
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1answer
47 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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2answers
58 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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1answer
32 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 ...
3
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1answer
72 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
43 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
109 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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2answers
86 views

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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1answer
117 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 ...
2
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2answers
97 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, ...
2
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1answer
126 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
45 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
99 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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1answer
150 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
67 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
500 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
97 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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2answers
140 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
181 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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1answer
238 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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1answer
70 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?
3
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1answer
221 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
205 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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0answers
77 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 ...
4
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1answer
89 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. ...
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1answer
1k views

What is the effect of adding salt to ice?

What will happen to the melting point temperature of ice if some common salt is added to it? How to justfy the answer?
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2answers
857 views

Can you heat water with additives?

I have been curious about this question for a while. If you want to warm up a large amount of water, is it feasible to do this by adding a substance that has an exothermic reaction with the water? ...
3
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4answers
5k views

How do I chill water without a refrigerator?

How can we chill water in a plastic bottle without a freezer or refrigerator? Scenario: I'm in the office and I have two plastic bottles of water (brought from home). I'm in the office for 3 to 4 ...
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1answer
195 views

Specific latent heat of fusion of a noble gas

Could someone explain to me where the additional energy goes when applied to an object in the state of melting (such as water) so that the temperature of the object does not increase, and could ...
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2answers
129 views

Egg-Detection in Pastries: An Analysis in Heat-Alterated Molecule Identification

I would like to know if anybody here knows of a method to detect the presence of ovalbumin--or any unique, egg-related molecule, in a baked good. Here I am anticipating that the "unique egg-related ...
2
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2answers
236 views

Better understanding the pyrolysis reaction

I'm no chemist, but much of my work revolves around biochar. I've always understood it with the following rough approximation: $$CH_2O + heat \rightarrow BC + H_2 + CO + CH_4 + HC's$$ where the ...
2
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1answer
557 views

Is the activation barrier of a reaction related to the free energy or heat of formation of its reactants?

The energy barrier for activation appears in the derivation of a bimolecular reaction through collision or transition state theory, but it seems that from looking at diagram such as this one it seems ...
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1answer
90 views

Why do we need to incubate this system for 18 hours at 60 degrees Celsius?

I am conducting a bio-chemistry related experiment and I have been unable to understand a step which is commonly performed. The procedure that is confusing me is outlined in the supporting ...