# Questions tagged [enthalpy]

A thermodynamic state function describing the total energy content of a system.

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### Calculating ΔH with non-integer coefficients in the balanced equation

I am working a practice problem out Ebbing's General Chemistry and for part of the problem I needed to calculate $ΔH.$ The problem considers the burning of ethane in oxygen to yield carbon dioxide and ...
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### Enthalpy Changes [closed]

0.50 g of Mg is added to a 50 mL HCl solution. The temperature increased by 5.2 degree Celsius. Calculate the enthalpy change for the reaction per mole of Mg that reacted.
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### What does higher electron gain enthalpy mean here?

While talking about ionic bonds my book states : Higher the value of electron gain enthalpy of the atom, greater the ease of formation of the anion from it, i.e., other atom should have high value ...
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### How to get the enthalpy of a reaction from the enthalpy of formations with Hess' law?

Let's consider a generic reaction: $$\sum_{i=0}^{i=I}n_{i}A_{i} \rightarrow \sum_{j=0}^{j=J}m_{j}B_{j}$$ where $n$ and $m$ are the stoichiometric coefficients, while $A$ and $B$ are reagents and ...
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### Thermochemical data for thiocyanatoiron(III) ion

I am currently writing a lab report about the formation constant of $\ce{FeSCN^2+}.$ All I could find online was a formation constant at $\pu{25 °C}$ $(890),$ which was 70% higher than the ...
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### Why when deriving the Clapeyron equation can you assume that dH = dq, as surely the pressure is not constant?

Part of the Clapeyron equation involves replacing $\Delta S$ with $\Delta H/T$. I can see the step from $\Delta S$ to $\Delta q/T$ but I'm not sure why you can replace $\Delta q$ with $\Delta H$. From ...
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### I can't find reaction enthalpy ∆H for water formation reaction

$$\ce{1/2 O2(g) + H2(g) → H2O (l)}$$ The tabulated value is $\Delta H = \pu{−285.8 kJ/mol}$ I'm using the bond energies values for each molecule and for some reason, I am getting a different result, ...
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### Change in heat of photosynthesis

Consider a plant that uses the energy it receives from the sun to do work (to undergo photosynthesis) to produce glucose. The minimum amount of work this plant can do to produce 1 mole of glucose is ...
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### Heat and work of glucose combustion

$$\ce{C6H12O6(s) + 6 O2(g) -> 6 CO2(g) + 6 H2O(g)}$$ When looking at glucose combustion I found that the change in Gibbs free energy is greater than the change in enthalpy. If we assume the process ...
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### Is the enthalpy of a molecule determined by the energy of the electrons? [closed]

I understand that the strength of the bond of a molecule is determined by the potential and kinetic energy of the electrons. I also understand that a reaction where the bond strength of the products ...
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### why is white phosphorous given to have ZERO standard heat of formation [duplicate]

why is white phosphorous given to have ZERO standard heat of formation?? while it is well known fact that white phosphorous is highly reactive and is obviously less stable than red and black ...
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### What is meant by electrons moving to lower potential energy?

I am currently learning about chemical bonds in chemistry, and came across somebody who wrote this (source): "Chemical bonds certainly "contain" potential energy, and the atoms want to move to a ...