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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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Is it possible my housemate broke our washing machine washing her labcoat? [closed]

I have a housemate that studies moleculair chemistry at the University. I'm not that big of a chemist myself as i'm more into programming. The problem: My housemate washed her labcoat in our ...
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1answer
20 views

Heat generation in exothermic reactions [duplicate]

Im thinking specifically of N2 + 3 H2 ⇌ 2 NH3. Its an exothermic reaction, therefore heat is generated. Im trying to understand how Chateliers principle interacts with this reaction. I understand that ...
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1answer
29 views

Heat transfer problem

For this problem, I'm wondering if the thermos should be involved in the heat transfer because right we have an equation in calorimetry: $q_\text{warm} =-(q_\text{cold} + q_\text{cal})$ A 125 g ...
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1answer
23 views

Specific heat problems [closed]

I am in need of help for my understanding in specific heat capacity. To be honest, I understand the lesson effectively, However, just a few days ago, I've encountered two similar yet different-in-...
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58 views

distillation of aqueous CAN solution for the purpose of a reversible and strong endothermic reaction in cool packs

I know calcium ammonium nitrate (CAN) is used for cold packs. By bending a small metal plate the salt gets dissolved in water (separated pack) and this process is endothermic. I would like to heat ...
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1answer
1k views

Why would a ~1 cm thick layer of argon be a significantly poorer conductor of heat than air?

In yesterday's new Periodic Video, Argon (new) - Periodic Table of Videos, after about 07 min 00 sec, Sir Martyn Poliakoff says: The final, and I have to admit perhaps slightly boring application ...
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1answer
36 views

Flexible & thermally conductive materials? [closed]

Quick question: Are there any common or easily obtainable materials that are thermal conductors, but also flexible? By flexible, I mean along the lines of a plastic bag, with similar or greater ...
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19 views

What is the specific heat and latent heat of an ethanol-water mixture?

How do I find the specific heat and latent heat of ethanol-water mixture? Let’s say the mole fraction of water is 0.3 and ethanol is 0.7. I am working on a project and needed values for these and ...
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31 views

Extraparticle transport limitations in het. catalysis: Varying Damköhler without affecting the external prater number (and vice versa)

Solving a question for exam preparation; In the lecture script it is asked: 1. When both external MT and HT limitations exist, derive a solution from the general mass and energy balances in terms ...
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1answer
48 views

Heat of Combustion

Methanol ($\ce{CH3OH}$) is regarded by many chemists as a possible liquid fuel for the future. The combustion of methanol occurs according to the equation: $$\ce{2CH3OH(g) + 3O2(g) -> 2CO2(g) +...
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23 views

Are there alternatives to sodium acetate?

I am wondering if there are any non poisoning alternatives to sodium acetate, which is used in those self-heating pads, that reaction can be kicked off by clicking a small metal plate? Specifically ...
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2answers
49 views

Why do aluminum and air have low specific heats?

According to Wikipedia, ...specific heat capacity is a function of the structure of the substance itself. In particular, it depends on the number of degrees of freedom that are available to the ...
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3answers
63 views

Why are calorimeters often made of materials with low specific heats?

When building calorimeters, a material with a low specific heat is often used (such as Styrofoam, aluminum, etc.). However, why would a material with a low specific heat be preferred? My thought ...
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1answer
24 views

Where can I find the total enthalpy and heat of dissolution in water of a given components?

I don't really have a background in chemistry but I'm actually studying in aerospace engineering, sorry if this question may seem trivial. I am interested in the decomposition process of the hydrogen ...
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1answer
34 views

Predicting the temperature of an object using the heat of its surroundings after a certain amount of time?

how would you predict what the temperature of something would be if it spends a certain amount of time exposed to heat from its surroundings? is this possible? ex. what temperature would a hot ...
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1answer
67 views

Calculate Heat of Atomisation [closed]

What is heat of atomisation of P4O6(s) Given heat of sublimation of P4O6 is x kJ/mol & P–O bond energy is y kJ/mol. What is heat of atomisation of P4O6(s) Given heat of sublimation of P4O6 is x ...
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1answer
33 views

Can air inside a high temperature (1300C) Kiln cause an explosion?

I saw many kiln designs that lack an opening for hot\pressurized air to come out , or any pressure valve. But when air is heated to such a high temperature (1300C) inside a closed chamber (the kiln), ...
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2answers
45 views

Sign of work done by the system in first law of thermodynamics equation

In the equation, $\Delta E = q - W$, according to my book, $W$ is positive when it is done by the system and negative when it is done on the system. But in this problem: $\pu{3600 kJ}$ heat is ...
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51 views

The sign of enthalpy of formation of magnesium oxide

I'm currently doing a lab to calculate the enthalpy of formation for $\ce{MgO}$. However at the moment me and my lab partner are having a disagreement. We've both calculated and agreed upon the same ...
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1answer
47 views

Is there any difference between “autoignition temperature” and “ignition temperature”? [closed]

Is there any difference between the "autoignition temperature" and the "ignition temperature" of a substance?
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30 views

Is there a direct relationship between specific heat and either thermal conductivity or heat transfer?

I am currently teaching high school chemistry, but my background is in physics. Our curriculum states that specific heat capacity is the amount of thermal energy required (or released) per 1 gram of a ...
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2answers
51 views

Fried potatoes absorbing oil [closed]

Suppose we bring a pan and put in it some oil and turn on the heat, before the oil could get very hot and nearly boiling, we put on the potatoes that start frying. Someone told me that if the ...
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1answer
33 views

What would happen if you heat volatile/flammable material in a vacuum? [closed]

Fire is an oxidizing chemical reaction, in the simplest sense it needs oxygen and fuel to burn in order to stay alight. But what reaction would you observe from a flammable substance like gasoline or ...
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1answer
57 views

Can heat capacity at constant volume for a gas decrease as temperature increases? [closed]

I found a function for the $C_V$ of a gas which is being heated under constant volume,but the function shows that the $C_V$ is decreasing. I was wondering if this is possible for any gas since I know ...
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1answer
48 views

slow down ice melting in water

Having to separate freshwater crabs for commercial fisherman while on the boat, we dump the crabs in ice water, as crabs aren't as aggressive and bite less when cold. There's only so much room on the ...
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2answers
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Why don't we consider VΔP when we define Q?

We only define $Q = \Delta U + W_\text{exp}$ (expansion work = $-P\Delta V$). If heat can cause $\Delta U$ and work, why work is defined only as expansion work in the first place where there are other ...
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1answer
50 views

Thermodynamics energy balance question help

I made the following attempt to solve this question.However I don't know how to find final pressure.I don't know how to find final temperature for both sides.Can you give me a hint?
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1answer
47 views

Enthalpy of formaton [closed]

today I was doing a set of HW problems regarding enthalpy and stumble upon one problem that I found confusing.It was the standard enthalpy of formation for CaCO3 is -1207.6 kJ mol when 30.7 g of ...
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0answers
36 views

Does specific heat capacity of the container have an effect on the exactitude of a calorimetre?

I'm doing a lab on what is the best material for a calorimetre. I chose glass, aluminum, styrofoam cup, paper/cardboard cup and a plastic cup. I've found that the cardboard cup was the best followed ...
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1answer
94 views

Why might copper have a lower heat capacity than lithium according to the Shomate Equation?

I've learned that according to Condensed phase thermochemistry data, according to NIST, the functions of heat capacity, enthalpy, and entropy can be predicted by the Shomate Equation: $$\begin{align} ...
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1answer
82 views

Material that changes color when changing phase from solid to liquid [closed]

I was asked and am wondering myself, what are materials that change color when molten? I could not find any examples online, but it really interests me. I would to get some examples which have one ...
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2answers
90 views

Can the change in the entropy of the surroundings always be obtained by dividing heat transferred by the temperature at which the transfer occurs?

Consider $\pu{1 mol}$ of an ideal monoatomic gas going through reversible isochoric heating from $\pu{100 K}$ to $\pu{1000 K}$. Calculate $\Delta S_\pu{sys}, \Delta S_\pu{surr}.$ $$\Delta S_\pu{...
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Why 'Enthalpy change' (Delta H) is equal to 'Heat transfer at constant pressure' (Qp)? [closed]

Why 'Enthalpy change' (∆H) is equal to 'Heat transfer at constant pressure' (Qp)? ∆H = ∆U + ∆pV, here only expansion work done by the sustem is added. If non expansion work is done on the system then ...
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If a reactor made up of alloy has ceramic coating inside, can the temperature inside be raised to 500C?

I would like to get a reactor fabricated for plastic pyrolysis. The temperature would maintained around 520C. The material processed would be Waste Polypropylene and Polyethylene. With the ceramic ...
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1answer
53 views

When boiling a liquid, how vapour pressure and ambient pressure get equal? [duplicate]

When boiling a liquid, how vapour pressure and ambient pressure get equal? As vapour pressure will increase, it will lead to increase in ambient pressure also. let, Initially there would be some ...
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1answer
26 views

Heat capacity determination

Since heat capacities are determined in a calorimeter taking advantage of the known heat capacity of water, how was the heat capacity of water originally determined?
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59 views

dq/T vs. CdT/T for measuring absolute entropy

In principal one could determine absolute entropy for a substance by integrating dq/T from 0K to the temperature of interest. However, I've seen this done using heat capacities, integrating CdT/T ...
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1answer
228 views

Thermochemistry - zero heat energy

We were just wondering in our chemistry class: is there any reaction which is neither exothermic nor endothermic?
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1answer
26 views

Won't gas thermometers break on using fixed volume of gas?

From the ideal gas equation, PV is proportional to T. Now if V is kept constant, we'll get Gay-Lussac's law. Now my question is: According to observations, we know that substances undergo a change ...
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22 views

Entropy and heat capacity [duplicate]

I’ve seen the entropy change for the surrounding in an exothermic reaction given as simply: ∆H/T However, entropy change depends on heat capacity and ∆H/T doesn’t take that into account. Wouldn’t the ...
3
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1answer
107 views

Am I Using the Correct Number of Significant Figures (Heat Problem)?

The question is: A patient arrives in the emergency room with a burn caused by steam. Calculate the heat, in kilocalories, that is released when $\pu{18.0 g}$ of steam at $\pu{100 °C}$ hits the ...
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Calculate work done by burning benzoic acid exposed to the free air

I'm self-studying and can't solve this problem in Ball's Physical Chemistry. Now, the errata shows that the answer in the book is not correct; still, I can not make sense of it. $(2.55)$ Benzoic ...
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1answer
64 views

How to know whether to add latent heat when calculating final temperature?

From the examples in my textbook, it is usually very easy to see whether you need to account for the latent heat when calculating the final temperature. For example, if you add 2 x 13 gram ice blocks ...
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Most optimum way to chill a gallon of beverage using liquid nitrogen? [duplicate]

What is the most optimum way to chill a beverage / sugar water (about 1.5 gallons at room temperature to +1 or 0 degree Celsius) using liquid nitrogen?
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38 views

Are there any dielectric fluids that have low viscosity, high specific heat capacity, are safe, non-reactive, and are relatively cheap?

I am looking for a dielectric fluid that fits the following conditions: Non-conductive (dielectric): Resistivity greater than $\pu{1 x 10^6 Ω*m}$ (or a conductivity less than $\pu{1 x 10^-7 S/m}$). ...
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368 views

Effect of temperature on vitamin c

We conducted an experiment in a laboratory: titrating tomato juice with an iodine solution. The indication was a freshly prepared solution of starch, which turns bluish black from reddish orange. ...
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50 views

Plastic contaminant in the kitchen (from a heated PP bag) - toxicity, cleaning up

In short, a pot of hot soup traveled in a PP bag and landed onto the kitchen table with a vivid unpleasant smell of plastic contamination. Based on the specifics provided below, I seek to identify ...
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1answer
120 views

What are common or reasonable values for a calorimeter constant? [closed]

In my lab class today we calculated the calorimeter constant for 2 styrofoam cups with a lid and a thermometer. I tried looking up on the internet an accepted value to see my error, but couldn't find ...
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2answers
317 views

Difference between Enthalpy and Heat transferred in a reaction?

We know at const pressure change in enthalpy is change in internal energy plus work done. Here by taking enthalpy as heat i can easily think the situation in mind that heat absorbed is due to the two ...
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33 views

Need help finding heat of calorimeter and reaction

We did a lab where we mixed $\ce{NaOH}$, water, and $\ce{HCl}$ together in different quantities, this is from trial 1: Results from my lab: We mixed $\pu{40ml}$ of water with $\pu{10ml}$ of $\ce{HCl}$...