terminology - What is considered room temperature in Celsius ...
2019年12月12日 · Room temperature is not among these, so ideally, an exact value must be specified alongside, if relevant, e.g. "the parameter has been determined at r.t. $(\pu{20 °C})$ ". German Wikipedia article presents an observation that in physical chemistry and statistical physics in European region the typical value taken for r.t. is $\pu{20 °C ...
How does water evaporate completely when at room temperature?
2017年10月15日 · But in doing so, it drains heat from its surroundings and thus stays at room temperature (or close to it), so there is still some fraction of molecules that can evaporate, and they do so, and more heat is transferred from the surroundings, and so …
Why don't room temperature superconductors exist?
2024年5月1日 · That said, there are higher temperature superconductors, and some do work near room temperature (well, perhaps in Hôtel de Glace, with the caveat at high pressure. For example, $\ce{LaH10}$ , at 170 GPa and -23°C.
What does enthalpy of formation at room temperature mean?
2020年9月11日 · The molar enthalpy of formation at room temperature is not dependent on the reaction effectively happening at the room temperature. It follows the general principle of state variables, being related to the Hess's law, which refers to the fundamental law of energy conservation. The principle says, that the change of enthalpy ( or any other state ...
When are transition state's energy barrier "reasonable" at a certain ...
2018年8月28日 · Using this website, input the activation energy and temperature and it gives half life. A reasonable half-life is up to the user, but more than 1 day is going to be super slow. Usually assume the transmission coefficient is less than 1 (e.g. 0.5). For example, an upper bound at room temperature is usually less than 25 kcal/mol $\approx$ 105 kJ ...
Why does water evaporate at room temperature? - Chemistry …
2013年12月20日 · 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, but at room temperature ($23\ ^\circ \mathrm{C}$), is there no excitation in the atoms or is there?
Energy a system at room temperature can supply?
2015年9月21日 · "This reaction requires XYZ activation energy, therefore it cannot happen at room temperature." is a sentence I find often in organic chemistry textbooks. Activation energies are steadily given in textbooks too.
When can a molecule be considered freely rotating at room …
2015年9月24日 · 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 chiral...
Why is CH4 a gas at room temperature but CH3Cl a liquid?
2015年11月16日 · It is a gas at room temperature with a boiling point $\vartheta_\mathrm{b} = - 23.8~\mathrm{^\circ C}$. Chloroform, which is indeed a liquid at room temperature ($\vartheta_\mathrm{b} = 61.2~\mathrm{^\circ C}$) is $\ce{CHCl3}$ or trichloromethane. You need to substitute three hydrogens with chlorine atoms to create chloroform.
How to determine if a compound is likely to become a solid at …
2015年5月22日 · A more mathematical way to look at this if you have empirical values for a compound is to look at the $\Delta G_\text{fusion}$ at room temperature. $\Delta G_\text{fusion}=\Delta H_\text{fusion}-T\Delta S_\text{fusion}$, where $\Delta H_\text{fusion}$ is negative (since it will free up energy in forming the solid) and $\Delta S_\text{fusion ...