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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Why does lithium move on the surface of water during the reaction?

If someone asks me to number the most notable "textbook experiments" I would definitely name "the comparison of the reactions of alkali metals with water" among the most favorites. We just happened ...
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23 views

Why and how does lycopene absorbance increase with heating?

Lycopene, which is a carotenoid and a phytochemical is the main reason for why tomatoes are radio-protective. Source 1 . Source 2 Let's cut to the chase: I was wondering if this claim of The ...
2
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24 views

Heat energy of phosphoric acid evaporation

Looking at a system in which phosphoric acid is concentrated in an evaporator which uses a constant recycle stream with a heat exchanger in this stream to heat the acid so that water evaporates out of ...
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12 views

Can N-Zorbit absorb wine and then dried while keeping the same alcohol level?

I'm trying to see if you could use the modified starch N-Zorbit, a maltodextrin, to absorb a low sugar wine (pinot noir for example) and then dry it while keeping the alcohol levels the same or close? ...
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15 views

solvent interaction with thermal paper

If you place a piece of paper that prints via a laser eg, fax paper or some receipts, on top of a piece of normal paper you have drawn on with a Bic Marking 2300 permanent marker, the image transfers ...
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70 views

Why is it obligatory to cool down the container of a sample to measure its mass in a lab?

We were doing an experiment about hydrated crystals and more precisely how to determine $n$ in $\ce{CuSO4.nH2O}$. After we heated the crucible we were to cool it down using a Desiccator. Then this ...
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37 views

How does heat and/or boiling remove vitamin C?

The www is full of crackpot claims about how various food treatments alter their nutrition content and it makes finding actual science very difficult. I am specifically interested in the vitamin C ...
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31 views

Why might my limelight experiment have failed and how can I improve it?

I was teaching the lime cycle to some children yesterday. I had a limestone chip (about 10g) held at the tip of a blue bunsen flame for several minutes. It decomposed and disintegrated but only glowed ...
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58 views

What compound can give off heat when it comes in contact with ice?

What compound is able to produce heat when it comes in contact with ice? The compound has to be able to produce heat multiple times. I was thinking of a compound that is similar to Calcium Chloride. ...
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42 views

How does this method of calculating the water equivalent of a calorimeter work?

I am doing a AP Chemistry lab in which we determine the heat capacity of a calorimeter (a concept that seems like it should depend on a lot more than just the calorimeter.) We have to calorimeters ...
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131 views

Is it possible to make broad spectrum light absorbing paint?

Is there such a paint / pigment that absorbs most wavelengths of light (beyond the visible light range) that can be used for solar heat generating applications? If not, would it be possible to make ...
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62 views

Why does the freezing point of a sample gas occur at a certain temperature?

From "North Carolina Measures of Student Learning: NC’s Common Exams Chemistry" (Source, Number 20): The graph below shows a cooling curve for a sample of gas that is uniformly cooled from ...
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28 views

Is the reaction exothermic or endothermic?

Is the following reaction endothermic or exothermic? Please note the following: When heat is removed from the system, the solution turns bright red (the reaction shifts towards the reactants side) ...
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221 views

What is “heating under reflux”?

When dealing with organic reactions, heating under reflux is often required, such as the oxidation of Toluene using acidified $\ce{KMnO4}$ and dilute $\ce{H2SO4}$ to Benzoic acid($\ce{C6H6O2})$ What ...
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38 views

Why do heavier elements have smaller specific heat values.

In the periodic table the trend is that as the mass of each element increase's the specific heat tends to go down. This seems to be counter-intuitive because if I am not mistaken as mass increase's ...
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52 views

Which formula is correct for calculating the heat of dissolution?

I want to calculate the energy change when a solute is dissolved in water. I know that I can achieve this by using the equation $q=mc \Delta T$. My question is does the mass ($m$) change with the ...
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1answer
44 views

Nuclear power: what material is the control rod made from?

My question: What type of material is used in the control rod of a nuclear reactor? (Nuclear power plant)
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23 views

What physical properties are manifested when an electron leaves Na and moves to Cl to form an ionic bond?

When an ionic bond is formed between Na and Cl, the lone electron in Sodium's outer shell leaves, and completes Chlorines outer shell. Are there any physical characteristics that I can use as an ...
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37 views

Can we define a new unit instead of specific heat that is constant with temperature rise?

Specific heat plays an important role in calculating energy and thus, heat, enthalpy and etc. But as I sighted the definition for calorie, I was surprised. A calorie is the amount of heat needed ...
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When will the mass of the reactant increase while being heated up?

There is some kind of system which measures the mass of an unknown solid substance as it heats up, of course for the elemental analysis of the very substance. (didn't really find a good name for that ...
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25 views

What is the specific heat of copper through its phases?

Specific heat is the amount of heat required to change the temperature of 1 gram of a substance by 1 Celsius. For instance, the specific heat of water in the solid phase is 2.059 J/gC and 4.184 J/gC ...
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10 views

How does refrigeration fluid temperature affect reaction efficiency in a plug flow reactor?

This question appeared in some sample exam problems, and I can't seem to figure it out. Some preliminary information: Reaction: Exothermic, irreversible, gaseous phase Reactor: Refrigerated, ...
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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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129 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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49 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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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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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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36 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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99 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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555 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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346 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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89 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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265 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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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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46 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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223 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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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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154 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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35 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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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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44 views

Calculate heat needed to vaporize water

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 ...
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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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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
103 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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91 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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53 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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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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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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148 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 ...