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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How do you melt magnesium without causing its combustion?

How do you melt magnesium without causing its combustion? I own a foundry capable of reaching temperatures around 2000 °F, and I recently bought some magnesium for melting before doing my ...
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Chemical reactions in plasma state

I am wondering about chemical reactions when the reactants are in a plasma state. Consider hydrogen and oxygen. Heated, these would react to form water. If hydrogen and oxygen plasma were combined, ...
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Why do helium balloons expand in volume as they go higher?

I realize as balloons go higher, the atmospheric pressure decreases, doing less to counteract the force of the gas particles pushing against the inner walls of the balloon. But at the same time, doesn'...
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Entropy and specific heat capacity

I have seen the equation $S(T_2)=S(T_1)+C_p\ln(T_2/T_1)$ where $C_p$ is the molar heat capacity at a constant pressure. I understand that this assumes that the temperature range is sufficiently small ...
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Super-saturated solutions

If a solution is super-saturated is it possible to add a substance to it without allowing it to crystallise? Does a change in temperature have to happen and reduce it's saturation if I want to add ...
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The effect of temperature on equilibrium

If the forward reaction is exothermic, and the reverse is obviously endothermic. I getting rather confused. If the temperature is increased the equilibrium will want to decrease the temperature. ...
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Why is the plateau on a heating curve in equilibrium?

From the interval of 100 to 140 minutes, why is the substance in equilibrium? I believe it's because at this interval, freezing and melting begin to occur at the same rate and, when two opposing ...
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Negative temperature as limiting case for two-level system

For N particles in a two-energy-level system, with energy levels being 0 and $\Delta$, the internal energy tends to $N \Delta /2$ as temperature tends to infinity. At this point, the occupancy of each ...
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Dissociation constant of molecular dinitrogen as a function of temperature?

I'm looking for the dissociation constant of molecular dinitrogen ($\ce{N2}$) as a function of temperature, $$\ce{N2 <=>[$K$] 2N} \quad K=\frac{[\ce{N}]^2}{[\ce{N2}]}$$ Casas & Bermelo (...
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Why there is no temperature scale tied to normal human body temperature?

Fahrenheit: The lower defining point, 0 °F, was established as the temperature of a solution of brine made from equal parts of ice and salt. Celsius: 0 °C was defined as the freezing point of ...
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537 views

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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Hydration reaction

Currently I'm measuring the rate of completion of a hydration reaction by putting a temperature probe in the middle of a cup full of reagents and measuring the temperature in an isolated box. The main ...
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How does temperature affect buffer capacity?

I am currently leaning towards an experiment on how certain factors affect the capacity of a phosphate buffer, and am wondering if temperature in any way affects the capacity of the buffer. I know ...
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What are the ideal pair of (everyday) elements to pair in a thermocouple

I want to create a thermocouple (to carry out experiments on thermoelectricity). I want to use the pair of everyday* elements (e.g $\ce{CuO}$ and $\ce{Al}$ wires) to create the thermocouple. The ...
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Is there any convenient way to warm water-based products to room temperature at home? [closed]

When it's cold outside, some household water-based products (liquid soaps, wet wipes) become cold to the touch as well. Since these products are used directly on the skin, their coldness may cause ...
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Solubility of NaCl in water [duplicate]

I learned that solubility of substance increases with increase of temperature. But I came to know solubility of NaCl doesn't increase when temperature is increased . So what is the reason for this ...
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Relation between activation energy and temperature sensitivity

In my reaction engineering textbook (Levenspiel), it is stated that reactions with high activation energies are very temperature sensitive, while reactions with low activation energies are relatively ...
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How to determine the specific heat of aluminum?

I have a question from my AP preparation book that I got wrong and do not understand the explanation: A student designs an experiment to determine the specific heat of aluminum. The student heats a ...
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Why is temperature considered as an important factor in deciding chemical reaction kinetics?

According to the Arrhenius equation, the rate of reaction is proportional to $e^{-1/RT}$. Here is a plot of the equation and its derivative with respect to temperature, both with respect to ...
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What is pure oxygen (gas) density as a function of T or P?

I'm looking for a set of data (ideally graphed) of $\ce{O2}$ density as a function of $T$ or $p$ (with constant $p$ or $T$, respectively). The best I've found is this 1948 paper which provides an ...
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Why does the rate of reaction increase less than proportionally to the increase in mass of catalyst?

I conducted an experiment where I wanted to speed up the decomposition of hydrogen peroxide with the use of a catalyst (potassium iodide). I used 5 different test tubes with 5ml of hydrogen peroxide ...
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How to determine parameters range?

I am into running some leaching experiments and wanted to study the effect of different parameters on my dissolution results. But I am confused with determining the parameters range. For example, I ...
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Whose solubility increases with increase in temperature?

Solubility of which among the following substances in water increases slightly with rise in temperature? (a)$\ce{KBr}$ (b)$\ce{KCl}$ (c)$\ce{KNO3}$ (d)$\ce{NaNO3}$ Answer is (b). ...
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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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Can Substances on Titan be Reacted at a Thermodynamic Gain?

Titan, a moon of Saturn, has readily available water ice ($\ce{H2O}$) and methane ($\ce{CH4}$) on its surface, at a frigid $\pu{93.7 K}$. It would be significant if these (or possibly, other ...
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How would you measure the rate of this SN1 reaction?

I am performing the following $\mathrm{S_N1}$ reaction: $$\ce{t-BuOH + HCl -> t-BuCl + H2O}$$ I would also like to measure the rate of this reaction, but I cannot seem to find a way. I initially ...
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Good sources to understand Stat Mech with concepts

I never had a proper course on Statistical Mechanics during my undergrad. I've tried picking up the subject by reading books, but I find that many focus on the mathematical derivations and I get ...
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There's an absolute zero, is there an “absolute hot”?

This might be more of a physics question, but is there a ceiling on how hot things can get? What happens at this temperature?
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Can every chemical compound be melted?

Are there any chemical compounds that disintegrate (without going into other chemical reactions; let's say in a vacuum) before reaching a melting temperature?
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Does temperature affect heat capacity?

My chemistry book says that heat capacity varies with temperature. There is no further discussion. Does the heat capacity of a given amount of substance really vary with temperature? If yes, why is ...
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How to find the temperature change of a solution?

Right now I'm doing a calorimetry lab and for the pre-lab we have been asked to determine the temperature change (in Celsius) of ammonium chloride in water. The question asks for the expected ...
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Reaction rate in terms of temperature change

For exothermic reaction where concentration changed in hard to measure, can I interpret the rate of reaction in terms of temperature change? For example, if the experiment is iron rusting reaction ...
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Enthalpy of a reaction changes with temperature, does this mean bond strengths change with temperature?

During chemical reactions, the bonds between atoms break or form to either absorb or release energy. The result is a change to the potential energy of the system. The heat absorbed or released from a ...
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Can a first order reaction change to a second order reaction under specific temperatures?

I'm studying basic reaction behavior. My question is: Consider a Continuous Stirred Tank Reactor (CSTR) where an exothermic, first-order, irreversible reaction takes place: $$ \ce{A ->[k_1] B} $$ ...
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Will supercritical nitrogen stay supercritical if we raise temperature and pressure high above critical values?

Nitrogen's critical temperature is -146.96 °C and critical pressure 33.96 bar. If we maintain nitrogen at 220 bar and 400 °C, what will be the state of $\ce{N2}$? Will it be still supercritical? I ...
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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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What's with the weird definition for the Calorie? [duplicate]

I came across this definition for the calorie, which I found... strange: "The (15°) calorie is the heat required to raise the temperature of one gram of water from 14.5°C to 15.5°C." Subsequent ...
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Why is the yield of substitution reactions decreased at higher temperatures?

This is according to my text : Increasing temperature favours elimination over substitution. This is because energy of activation for elimination is higher than that of substitution since higher ...
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How many significant figures?

In Brown, Theodore E.; LeMay, H. Eugene; Bursten, Bruce E.; Murphy, Catherine; Woodward, Patrick; Stoltzfus, Matthew E.. Chemistry: The Central Science (Page 35). Pearson Education. Kindle Edition, an ...
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How do I dissolve sodium oleate in distilled water

I wanted to know how to dissolve sodium oleate powder in distilled water? Does it have to be at a certain temp? I need a 2% solution
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What is the difference between fractional freezing and fractional crystallization?

More simply put, what is the difference between freezing and precipitation when considering a mixture? Take two scenarios: First a mineral in water. If the temperature of this solution is lowered, ...
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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 there no standard temperature?

The standard state for a gas is defined at 1 bar of ideal gas. Why isn't there a corresponding standard state temperature?
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Why there is no one scale universal in measuring temperature? [closed]

a) Why we use Fahrenheit scale for measuring body temperature, Celsius scale for whether report, and for no use in daily life of kelvin scale it has importance in scientific calculations or in my ...
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Temperature dependence of molarity and molality

My textbook informs me that Molarity is dependent on temperature, whereas molality is not. I'm aware of the definitions of both molarity and molality, but consider this scenario: A solution of $\...
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The effect of temperature on the caffeine intensity

Does the brewing temperature have an effect on the caffeine level? For instance, coffee with 100*C have higher caffeine level compared to coffee with 50*C?
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Can we freeze water at −1 °C?

Is it possible to freeze water if it is directly exposed to $-1\ \mathrm{^\circ C}$ and not $0\ \mathrm{^\circ C}$? Is freezing point the minimum temperature at which a substance can be froze?
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What is the formula for evaporation rate of water?

I did my own research, and according to The Engineering Toolbox,the formula for the evaporation rate of water is as follows: $g_\mathrm h = \Theta A (x_\mathrm s - x)$ $g_\mathrm h$ = amount of ...
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Liquids that keeps the lowest temperature for the longer time after being frozen

I am working on a personal project, however I know nothing about chemistry and I would like to ask you guys for a quick question. I need to use a liquid for my project, which after being put into a ...
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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 ...