Questions tagged [temperature]

A measure of the average kinetic energy of the particles in a sample of matter; may be expressed either in kelvin (symbol K) or in degree Celsius (symbol °C).

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45 views

Detecting trash (plastic) burning smoke with sensors

I’m not a chemist, but a software engineer. I’m trying to build a device that could detect if someone is burning trash (mostly plastics and similar materials) vs wood or diesel. At my disposal I have ...
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Arrhenius equation using concentration

I've been conducting some experiments to determine the temperature dependence of a reaction. To do this, I've been conducting the experiments at different temperatures and generated a graph of $\ln{[\...
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Does cooling a potato change the nature of its carbohydrates?

A talk-show guest of Joe Rogan claimed that cooling a potato after cooking creates "resistant starch" that's better for human consumption https://www.youtube.com/watch?v=niwqfwA2Lb8 The claim is ...
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Gas Law - increasing temperature with constant volume held

I've set up a simple experiment to look at the ideal gas laws. My experiment is relatively simple in that I have a metal tube which is capped on one side. I am then pressurising the tube with air to ...
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How can equilibrium lie to one side ? Surely it’s not at equilibrium anymore? [closed]

Surely they’re not at equilibrium any more? I understand that a favourable condition can make a reaction in one direction go faster, but then surely either the forward or backward reaction is faster ...
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70 views

Why does the rate of the reaction decrease with an increase in temperature?

Why does the following reaction $$\ce{2NO + O_2 -> 2NO_2}$$ have negative reaction coefficient, i.e., why does the rate of the reaction decrease with an increase in temperature ? I have been ...
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Is temperature double-counted in the Gibbs free energy equation?

Complete amateur here. When looking at one form of the equation deriving the change in Gibbs free energy for a given chemical reaction, the terms change in enthalpy, and the negative product of ...
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Derive expression for average heat flux in heat exchanger

The single-tube heat exchanger is used to increase the temperature of fluid I from $T_{b1}$ to $T_{b2}$. The heating oil (fluid II) used for this task enters at temperature $T_{02}$ and leaves at ...
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A formula for the refractive index of a gas dependent on temperature and pressure

I am in search for a formula that gives me the refractive index of a gas at a given temperature and pressure. Does such a formula exist? Ideally the solution should have this form: $n_g(t, p) = \...
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157 views

What emits the least radiation when hot?

What element with a high vapor point the emits to least light or radiation when heated to its vapor pressure point in a vacuum? Ideally I would like to know in 0 gravity and 0 pressure which ...
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How to determine omitted units in a publication

I have found a 1954 paper in J. Am. Chem. Soc. which gives various temperatures in degrees but does not specify units. A snippet of the introduction is: Titanium reacts appreciably with fluorine ...
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Ideal gas constant applied to water, lead, and other non-gases

I've asked a number of chemists why the ideal gas constant is in the equation for Gibbs free energy, and all say the same thing: "The name is a relic of the argon gas chamber used to determine energy ...
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Is heat just a change in temperature?

According to my chemistry textbook, heat is defined as "Energy that is exchanged because of a difference in temperature or a change in phase." My textbook also says, "Heat is a form of energy. ...
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Freezing point lowering for a mixture of many liquids

I have been taught that if I have a solute of molality $m$ mixed with a liquid, the freezing point in lowered by an amount $K_\mathrm{f}\cdot m$ where $K_\mathrm{f}$ is the molal freezing depression ...
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Do endothermic reactions have a higher absolute change in temperature than exothermic reactions? [closed]

or does it depend on the reaction itself. I am conducting an experiment and the endothermic reactions have temperature changes of at least 8 degrees while the exothermic reactions have a change in 1 ...
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What could cause a peak to split into 2 resonances as temperature increases in NMR spectroscopy

I understand that some peaks may coalesce upon an increase in temperature due to an increase in free rotation, this does occur with some peaks in my data. Why might you see a peak split into two other ...
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How to take a sample of a hot salt solution without it precipitating in the cooler glassware due to the difference in solubilities at different temps?

I'm doing an investigation to see the effect of temperature on the solubility product of strontium hydroxide. I made a supersaturated solution left in the oven overnight at 85°C for equilibrium to be ...
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Why does increase in pressure cause a increase in boiling point [closed]

When we increase the atomospheric pressure pressure above the solution , the boiling point of a solution increases. Why does this happen?
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Cerium (CeO) behavior in Glass Polishing?

I am basically working in semiconductor industry and I specifically taking care of CMP (Chemical Mechanical Polishing). We did polish glass (borosilicate type of glass) and we are using slurry (which ...
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How does increasing temperature reduce the efficiency of solar cells?

I've seen several answers and trying to confirm. 1) Does temperature increase the ground state energy of electrons once they reach the positively doped semiconductor, thus reducing the voltage ...
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Why is the auto ignition temperature of petrol higher than that of diesel? [closed]

I can't find any reasonable explanation please help.
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333 views

Decrease in temperature of a aqueous salt solution decreases conductivity

Why does the conductivity of a water solution drop as the temperature decreases? How are these two related?
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109 views

Meaning of red heat

I have two reactions below. What is the difference between red heat and normal heat? Is it related to iron as a catalyst when it is red hot?
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pH change with temperature

I understand that the pH of solutions decreases as the temperature increases but is there a reason as to why some solution's pH decreases more than others even if the temperature change is the same?
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Is there a Material that is High Heat Resistent and soluble?

What i‘m looking for is any sort of material that dissolves, while being able to resist temperatures of up to 1000°C. And it doesn‘t have to resist during dissolution, only while it‘s solid. And the ...
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Are enzymes with superior catalytic properties more sensitive to temperature changes?

I am wondering whether enzymes with superior catalytic properties are more or less temperature sensitive than average enzymes. I know that enzymes lower the activation energy, Ea. So the more ...
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Explanation of phase changing/solid and liquid water existing in the same container at same temp [closed]

I was trying to explain to a friend the other day why when ice and water are in the same container, the water is 32 degrees Fahrenheit or 0 celcius, but not frozen, because the ambient temp is above ...
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Is it safe to heat fluorite (CaF2) to 140 °C?

For the manufacture of the optical system, we need to heat the fluorite ($\ce{CaF2}$) lenses to $\pu{140 °C}$. Is it possible: for some poisonous gas to be emitted? ($\ce{F2, HF}$ or other) for ...
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Why do we use Δ to mean heating?

To express heating, we usually use $\Delta$ over reaction arrows like \begin{align} \ce{CaCO3 ->[\Delta] CaO +O2}. \end{align} Why do we use $\Delta$ to mean heating during chemical reactions? I ...
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239 views

Why do Gas Laws only use Kelvin Temperature? [closed]

I didn't see this in any other question, although it seems to be a fundamental question of the gas laws. I understand that Charles' Law practically has to use Kelvin temperature, because you would end ...
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How is it that earth's inner core is still solid?

Earth's inner core is made up of an alloy of Iron and Nickel. The important note here is that it is solid. The temperature at the inner core is about $5,763K = 5,490\text{ degrees C}$. Now the ...
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Why do higher intermolecular forces lead to a higher change in temperature?

We performed an experiment in chemistry where tissue paper soaked in various chemicals was wrapped around the end of a temperature probe. The chemicals with stronger intermolecular forces had a lower ...
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How does Boudouard reaction influence the temperature?

I've a question that is giving me a lot of troubles: I'm depositing and gasifying Carbon by varying a flow rate of $\ce{CO}$ and $\ce{CO2}$ and by using the Boudouard reaction ($\ce{2CO -> C + CO}$)...
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Why do we still need to know about the Rankine temperature scale?

I am learning process principles in chemical engineering and I was taught various temperature units like Fahrenheit, Celsius, Kelvin, and Rankine. I see the first three being used quite commonly, but ...
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Up to which temperature and pressure can dendrimers (PAMAM) be stable?

I am preparing PAMAM (poly amido-amine) dendrimer and I want to know up to which temperature and pressure can it be stable?
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At what temperature can molecules no longer form?

// hyper simplistic terminology in use for the question - apologies. Molecules are formed by atoms bonding together, and those bonds have an equivalent energy. At what temperature does the thermal ...
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Is there a better model than the Kinetic Theory of Gases [closed]

I'm looking for a better relationship between the Kinetic energy of a gas and it's Temperature, and also how they vary with gravity (not altitude, just gravity!). So is there a model better than the ...
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Which is the cheapest plastic that retains its structure at 85 °C or higher temperature?

In an academic project, I need to protect some electronics components from heat (around 85 °C). I am searching for both a cheap plastic film and a cheap plastic to be used in a injection molding ...
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Process of transferring kinetic energy in regard to photons. [closed]

Now I know that temperature is the average kinetic energy of atoms, molecules and compounds. Photons increase the kinetic energy/temperature of molecules since photons are pure energy. Hence, wouldn't ...
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Reaction direction change based on phase of reactants and products

I am curious specifically how the entropy of a reaction will change if the phases of the reactants and products at different conditions change. For instance, a reaction $$\ce{O2(g) + C(s) -> CO2(...
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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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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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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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Does hydrogen peroxide - urea become more active when illuminated?

Dentists' tooth whitening systems and consumer kits use gels containing carbamide peroxide, also known as hydrogen peroxide - urea. Dentists use a light activator: (image from Wikipedia). Consumer ...
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Will ice be cold or not when formed using pressure? [closed]

We know that ice can be formed either by lowering the temperature of water or by applying more pressure. If we lower the temperature of water the ice so formed will be cool which is obvious. If ice ...
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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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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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Why does the distance between molecules increase when the temperature is raised?

I have learnt that when we heat ice-like substances it changes to water and when I asked my teacher she said that the distance between molecules increases. When I thought about it a bit more a ...
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Equilibrium, temperature change, and prediction in constant volume

When it's constant volume, change of $T$ (Kelvin temperature) in a reaction equilibrium system won't change the volume. Let's say we change the temperature from $T$ to $2T$ of this reaction at ...
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How does water flows through pipes in cold countries?

This question occurred to me when I looked into the fridge, where the water had frozen due to very low temperatures. If the water freezes due to low temperatures (0 degrees Celsius), then how can it ...