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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2k views

When can a molecule be considered freely rotating at room temperature?

This question sparked from a long discussion in chat about the nature of $\ce{H2O2}$ and whether that molecule can be considered to rotate around the $\ce{O-O}$ axis (and hence display axial chirality)...
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Reversible and Irreversible adiabatic expansion

A $\mathrm{200.0\ m^3}$ balloon at $253.0\ \mathrm K$ ascends to a higher altitude. If the initial pressure inside the balloon is $325$ millibar, and it ascends to a latitude with a pressure of $7.45$ ...
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How can decreasing in temperature indicate an endothermic reaction?

I’m really wondering how can decreasing the temperature refer to an endothermic reaction. I faced this when I was calculating the heat of a reaction Q in a constant-pressure calorimeter. What I ...
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At which temperature does carbon monoxide explode?

I had doubt whether carbon monoxide explodes or not. I checked out this resource and found out that carbon monoxide explodes when heated. But they didn't mention the temperature at which it explodes. ...
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Why does water evaporate at room temperature?

When water temperature reaches $100\ ^\circ \mathrm{C}$, the molecules get so excited that the hydrogen atoms lose the bonds to the oxygen atom and therefore the water starts to become gas. I get that,...
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How is Negative Temperature Hotter than Infinite Temperature?

Recently I have read articles stating that negative Kelvin has been achieved. I was a bit speculative at first as I though how can you get cold than 0 Kelvin, but after doing some research it makes ...
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Prove that a 10-Degree Temperature Increase Doubles the Rate Constant (k), when the Activation Energy is Approximately 50 kJ/mol

I read that increasing the temperature by $10~^\circ\mathrm C$ will double the rate constant ($k$), when the activation energy for the reaction is relatively close to $50~\mathrm{kJ/mol}$. However, ...
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Does the Maxwell-Boltzmann distribution apply to gases only?

The Maxwell-Boltzmann distribution can be used to determine the fraction of particles with sufficient energy to react. I know that the curve applies to gaseous reactants and would like to know whether ...
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Negative Kelvin Temperature

I remember my Physical Chemistry Professor saying that very tiny negative Kelvin temperatures have been achieved on the quantum level. Is this true?
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Can paper burn without oxygen or air?

If you put a paper inside an oven vacuum packed and go beyond $250~\mathrm{^\circ C}$, will it burn? There's no oxidizer. If not, what will happen?
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Why do some solid chemicals dissolve better in colder water?

I just discovered that some solid chemicals, such as $\ce{Na2SO4}$, dissolve better in cold water than hot water from here and would like to know if there is any particular reason as to why. Is it ...
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Is sublimation caused by an environmental difference or an element's composition?

I was having a conversation when the topic of sublimation came up. Prior to the discussion, I had always thought that sublimation was caused by a great pressure/temperature difference, but another ...
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Why won't increasing the temperature increase the solubility of a gas in a liquid solvent?

If I raise the temperature of a solution of a gas in a liquid solvent, why won't the solubility increase? Increasing the pressure will increase the solubility, but increasing the pressure doesn't ...
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Does the initial rate in the reaction of magnesium powder with nitric acid depend on the volume or the concentration of the acid?

For the question regarding the initial reaction rate, I don't quite understand why the answer is D. If I calculated the number of moles from the volume and conc, I would get A=0.4 moles; B=0.2 moles;...
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Why is absolute zero unattainable?

We were dealing with the Third Law of Thermodynamics in class, and my teacher mentioned something that we found quite fascinating: It is physically impossible to attain a temperature of zero ...
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Are complex ions thermochromic?

Does raising the temperature of a complex ion (formed from a transition metal ion and ligand(s)) affect its color? For example, if the temperature of $\ce{[Cr(H2O)6]^3+}$ is raised, will its color ...
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Why is the Haber process carried out at such high temperatures?

On a large scale, ammonia is prepared via the Haber process: $$\ce{N2(g) + 3H2(g)->2NH3(g)} \qquad \Delta _\mathrm{f}H^\circ = -46.1~\mathrm{kJ \cdot mol^{-1}}$$ The optimum conditions for the ...
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How do I control the negative temperature in an experiment?

If one were to adjust the positive temperature in an experiment, they would use a heating plate, or a stovetop. How would one adjust negative temperatures in an experiment? (Not keeping the ...
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Chemical Equilibrium - Why does changing the temperature shift the equilibrium?

I know that raising the temperature in a reversible chemical reaction causes the equilibrium to shift to the endothermic side. I know that $\Delta G = \Delta H − T\Delta S $ but I don't know how to ...
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At what temperature (in kelvin) are most of the elements on the periodic table liquids?

This question is out of pure curiosity. At what temperature are a majority of the elements on the periodic table in a liquid state/phase of matter? For the purpose of this question, assume the ...
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Why is so different the temperatures of a compressed gas compared to a liquid/gas mixture of the same fluid and they are both at the same pressure?

Why does $\ce{C3H6}$ gas when compressed (in a centrifugal compressor) comes out with a pressure of $\pu{16 bar}$ and $\pu{90 °C},$ and when it is a mixture of $\ce{C3H6}$ liquid/gas stored inside of ...
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Henry's Law with varying temperature

I am trying to determine what the derived partial pressure would be for CO2 in the global atmosphere from historical inconstant temperatures and CO2 concentrations of the global atmosphere: Is it ...
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Temperature measurement

Consider some liquid in a beaker. I am measuring its temperature using a thermometer. When i put my thermometer's bulb in the liquid, the particles of the bulb gain the same kinetic energy as of the ...
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Why is −78 °C a magic temperature for organic reactions?

In many organic reactions that I have seen, running the reaction at $\mathrm{-78\ ^\circ C}$ seems to be quite a popular choice, but I've never seen any explanation for this. What makes this ...
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What is the reason for anomalous expansion of water?

What is the reason for anomalous expansion of water? Why doesn’t it simply expand on heating or contract on cooling? Why it shows anomalous behavior at 4 degrees Celsius? Why not on 4.6 or 10 (or ...
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What are the degrees of freedom that define the temperature of an ionic solid (such as sodium azide)?

Degrees of freedom describe the different ways atoms move in a sample. For a pure ideal gas made of non-linear molecules, there are 3N degrees of freedom (N is the number of atoms in the molecule), 3N-...
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What is an example of a very low temperature endothermic reaction?

Shakashiri describes the reaction of solid Ammonium Thiocyanate and solid Barium Hydroxide Octahydrate resulting in an endothermic reaction leading to subzero temperatures. I've performed this ...
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Why does heating transform the aquacomples of slightly acidified cobalt(II) chloride solution to the chlorido complex?

There is a famous demonstration where, if you mix a $\ce{CoCl2}$-solution with the right amount of $\ce{HCl}$ you will end up with the pink $\ce{[Co(H2O)6]^2+}$ complex but when heating it to boiling ...
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Safe endothermic reaction that gets below freezing?

I have a project/idea I am working on but I am only 14 years old and I need some help. I'm looking for an endothermic reaction that gets below freezing, but the chemicals before the reaction and ...
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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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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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Has a concept of temperature ever been defined in the context of a single atom?

I wonder if this answer to What would happen if we supercool and then superheat an atom very abruptly? goes far enough. I almost wrote the comment: I don't think we can even talk about the ...
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How could I find the solubility of hydrocarbons such as iso- and n-Butane in liquid Methane?

I am trying to figure out the dissolution capacity of iso and normal butane in methane at very low temperatures (110K). This would allow me to make compositions that prevent freeze out of these ...
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Density of water and temperature

Is there a formula that shows how the density of water is affected by temperature? For example, with the speed of sound it can be shown how temperature will affect the speed: $$V = 331\ \mathrm{m/...
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Does the density of a liquid and gas phase of a substance(nitrogen or water) converge when reaching critical point

I know that the there is no difference in density in a liquid and a gas phase of a substance after the critical point. But I do want to know if this difference in density is more continuous or if it ...
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Evaporation Rate of Water

In AP Chem we did a lab investigating the relationship between vapor pressure and water temperature. The relationship is linear and as the vapor pressure approaches atmospheric pressure, it begins to ...
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Kc only effected by temperature?

This makes little sense to me, with a lot of contradictory statements I have learnt. For example: $$\ce{N2 + 3H2. <--> 2NH3}$$ ($\mathrm{\Delta h = -46.2~kJ~mol^{-1}}$) I have been told a ...
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Can formaldehyde be stored at a higher temperature than room temperature?

I have studied that formaldehyde stored at temperature lower than room temperature convert into 1,3,5-oxane. So, it's not stored at colder temperatures. But my question is - Can a similar degrading ...
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What is the reason for mpemba effect? [duplicate]

Under some circumstances, warmer water can freeze faster than colder water.
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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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Will heavy gases sink in a closed refrigerator?

Let's assume there is no air movement in the refrigerator. Is this enough for sinking of nitrogen? If not in what (low) temperatures we will start to see evident distinction between the composition of ...
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Determining boiling point on a created temperature scale

1.Assume that you construct a thermometer using gallium as the fluid instead of mercury, and that you define the melting point of gallium as 0 °G and the boiling point of gallium as 1000 °G. What is ...