Questions relating to heat and its relation to other forms of energy in chemistry.

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Can a supersaturated solution get cooler during crystallization?

Suppose we have a supersaturated solution that is isolated from the environment. Some of the solutes condense into a crystal in the solution. Is it possible for the solution to get cooler during this ...
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Can carbon subnitride be used as a fuel with similar properties to gasoline?

I am trying to figure out if Dicyanoacetylene, aka carbon subnitride, aka $\ce{C4N2}$, can have a similar reaction with air as gasoline, or if it only creates a lot of heat but not much expansion? As ...
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What are the bubbles and crystals found in sodium acetate hot packs after use and storage in the solid form?

When sodium acetate trihydrate hot packs are regenerated soon after activation, they regenerate to a clear liquid upon boiling (typically with an air bubble that was not present in the new pack) On ...
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1answer
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When is the Assumption that Enthalpy is Constant over Temperature Change Invalid?

In a question, I was asked to integrate the Gibbs-Helmholtz equation to derive some formula. Then the next question asked: Identify one assumption that you have made in deriving the above equation ...
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why is methane and oxygen at room temperature unstable? [duplicate]

A mixture of methane and oxygen at room temperature is said to be thermodynamically unstable with respect to carbon dioxide and water, but kinetically stable. Explain to me what this means, and how ...
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Fe^+2----> Fe^+3 + 1e , for this rxn the oxidation potential which i found on internet is -0.77V. But how can it be negative?

$\ce{Fe^{2+} -> Fe^{3+} + e^-}$ , for this reaction the oxidation potential which I found on internet is $-0.77 \,\mathrm{V}$. But how can it be negative? Negative oxidation potential means ...
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I need help Calculating the added amount of NaOH at each step and plot the titration curve? [closed]

if you can show me an example that would be greatly appreciated with the calculations. Thank you Burette Reading --- VolumeOf NaOH ------ pH 27.41------ ---------0.00------ -------3.39 ...
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Calculate the added amount of NaOH at each step and plot the titration curve? [closed]

if you can show me an example that would be greatly appreciated with the calculations. Thank you Burrete Volume pH reading Of NaOH (ml) added (ml) 27.41 0.00 ...
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27 views

What causes exactly the bubbles in soda eg?

I know that thanks to irregularities (nucleation sites such as tiny scratches) in a glas the molecules can get into that hole and growing bigger and after a certain time a bubble is getting above. ...
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40 views

Which is the specific heat of human body?

I'm studying about heat transfer and I wanted to know if there exists a specific heat of the human body or how one studies the human body's heat transfer.
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1answer
71 views

Deriving an expression for dU as a function of V and T

I'm currently preparing for a physical chemistry exam tomorrow, and was given the following question for practice: Derive an expression for $\mathrm{d}U$ as a function of $\mathrm{d}V$ and ...
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2answers
56 views

Difference between microcanonical and canonical ensemble

I feel a little unclarity about this. Canonical ensemble is pictured as many systems in heat reservoir of infinite capacity having $N$ (number of particles), $V$ (volume) and $T$ (temperature) ...
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Resultant temperature of mixture

**Question: ** There are 2 flasks of equal volume, connected by a narrow tube of negligible volume, filled with nitrogen gas. When both are immersed in boiling water, the gas pressure inside the ...
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1answer
31 views

What is the relation between chemical thermodynamics and chemical kinetics? [closed]

Can one be understood on the basis of the other or are they not interrelated at all? The first thing my kinetics textbook demonstrated was how thermodynamics ignores time taken for a process whereas ...
3
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2answers
72 views

What is the qualitative definition of enthalpy in beginner terms?

So in my coursebook it says enthalpy is a property that accounts for the increase in internal energy and the accompanying work done by the system and that its equal to the sum of the internal energy ...
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28 views

How can be explained why the specific heat of ice is twice as low as liquid water?

To raise the temperature one degree of ice costs about 2000J but for liquid water it is 4000J. The reason for that is that the freedoms of vibrations rotation and translations of ice are lower and the ...
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29 views

Thermochemistry Decomposition of Water to Atoms

Given $ΔH°_f = −241.8 kJ/mol H_2O_{(g)}$, $ΔH°f = −285.8 kJ/mol H_2O_{(l)}$, and $O−H → O + H$ has $ΔH° = 429.91 kJ/mol∙rxn$, how can we determine the $kJ/mol$ required to decompose $H_2O$ into atoms? ...
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26 views

Exothermic reaction and temperature increase

I had to study the oxidation of nickel in a reactor at high temperature. Basically, air at a certain temperature is sent into the reactor to react with the nickel (that was probably used as a catalyst ...
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1answer
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What is the meaning when it is said “Temperature of an Oxyacetylene Torch is 3500 degrees Celsius”?

I don't think flame is anything but the product at that temperature but I am not sure. What exactly is flame? And I think the correct statement should be that the exothermic reaction here produces ...
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1answer
38 views

Temperature change when volume halved

For this multiple question: The correct answer is B. However, I don't understand. You are halving the volume so for the original solution the number of moles of HCl is 0.1 moles and in the ...
3
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1answer
71 views

Free energy of an ideal gas

I want to calculate the Gibbs free energy for an ideal monoatomic gas, i.e. $$U=\frac32nRT.$$ Free energy is defined as $G(T,p)=H-TS$ and using the definition of enthalpy $$G(T,p)=U+pV-TS=U+nRT-TS.$$ ...
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Work done during dissolution of carbides

Question: 1 mole of each $\ce{CaC2}$, $\ce{Mg2C3}$, $\ce{Al4C3}$ react with excess water in separate open flask. Work done during dissolution shows the order ...
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1answer
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Internal energy change during phase change

Ice at $\mathrm{0^\circ C}$ is converted to water at $\mathrm{0^\circ C}$. If $\Delta H$ for the transition of ice to water is $\mathrm{1440~cal}$, calculate the change in internal energy. Since ...
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1answer
66 views

General expression for entropy and free energy

The specific heat capacity of a solid at constant pressure and low temperatures is given by $$c_p=aT+bT^3$$ with $a$ and $b$ are constants. How can I calculate a general expression for the entropy ...
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Liquid nitrogen superheating with a layer of oil?

edit: Thanks Ivan, also further research. Pure water can be superheated to a few degrees above 100 degrees. However I remember reading reading that water can be superheated to even higher ...
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Use of statistics in this field

I am currently pursuing a statistics course and I an interested in knowing how can statistics help this field in future. (I am interested because I love chemistry very much) Specifically, are there ...
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32 views

Chemical potential and it's implications in an open system

Take the fundamental equation for the Gibbs free energy of a system: $$dG=VdP-SdT+\sum_i\mu_idn_i$$ Thus, the chemical potential can be defined in terms of the Gibbs free energy as follows: ...
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1answer
41 views

Utility of Delta G

What is the main utility of delta G? As far as I could understand, if we do not know whether the reaction we are dealing with occurs in nature or not, we would not be able to tell in which direction ...
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How is Gibbs-Donnan equation derived?

Could it be derived from fundamental relations of gibbsian thermodynamics and other relevant physics? Or is the equation solely representing an experimental fact that only approximates the more ...
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1answer
77 views

Calculating Final Temperature and Volume of Adiabatic Expansion

A $\mathrm{5.00\ L}$ sample of $\ce{CO2}$ at $800 \ \mathrm{kPa}$ underwent a one-step (irreversible) adiabatic expansion against a constant external pressure of $100\ \mathrm{kPa}$. The initial ...
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2answers
69 views

Spontaneous/Non-Spontaneous Reactions and Reversible Reactions

my Textbook of chemistry states thus: "Reversible reactions constitute a limiting case between spontaneous and non-spontaneous processes." So what does this mean? That some of the reversible reactions ...
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1answer
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Enthalpy of Reversible Adiabatic Expansion

Suppose an ideal gas undergoes a reversible adiabatic expansion. Explain why the the enthalpy change is given by $\mathrm{\Delta H = c_v\Delta T}$ My Attempt I know that $\mathrm{q = 0}$ and ...
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Endothermic reactions with significant activation energy

Are there any chemical reactions where in order to induce the reaction, you have to heat up a substance but after the reactions happens, the substance is much colder than even before you started ...
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1answer
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Calculating entropy change of surroundings

I have seen many similar questions but have not found my answer. Why do we use the actual heat involved in the process to calculate entropy change of surrounding? The only answer I can think of is ...
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1answer
238 views

Phosphorus standard state

Why is white phosphorus considered to be the standard state of phosphorus although it is only metastable? Red phosphorus is thermodynamically more stable than white phosphorus, yet it is not the ...
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2answers
36 views

Does the change in Gibbs free energy depend on initial and final concentrations?

Suppose there is a decomposition reaction, and by varying different factors, the equilibrium can be disturbed to alter the final concentration of compounds. So, does the value of ∆G here depend upon ...
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1answer
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Heat in Isothermal process

I have a book that contains the following line :- In an isothermal expansion, the gas absorbs heat and does work But , if a gas absorbs heat , then how can its temperature remain constant ?(as ...
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1answer
107 views

Why dynamic equilibrium exists?

We know that at equilibrium Gibbs energy is minimum. We also know that at equilibrium both forward and reverse reactions occur simultaneously, and also we know that for a reaction to be spontaneous ...
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Active mass,Pressure and concentration

The concentration is connected to the activity via $$a(\ce{A})= \gamma_{c,\ce{A}}\cdot{}\frac{c(\ce{A})}{c^\circ},$$ where the standard concentration is $c^\circ = 1\:\mathrm{mol/L}$. At reasonable ...
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1answer
58 views

Why at constant pressure and temperature Gibbs energy change of a process can be negative?

$dG < 0$, for a spontaneous reaction at constant Temperature $T$ and Pressure $P$, this means that at contant $T$ and $P$, $dG$ can be negative $dG = VdP -SdT$, this means that at constant $P$ ...
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1answer
60 views

Can the entropy of the universe be calculated?

If for the combustion of magnesium $\Delta S^\circ = -30~\mathrm{J~K^{-1}}$ and $\Delta H^\circ = -604.94~\mathrm{kJ}$ at a temperature of $25~\mathrm{^\circ C}.$ Then how can we calculate entropy of ...
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1answer
19 views

Calorimeter and bond energy

Why does 1,3-Butadiene has different standard heat of formation value calculated from calorimeter than the one calculated from bond energies?
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Enthalpy of combustion [closed]

If the energy is released as heat when liquid propanone is burned in a bomb calorimeter at $300\rm~K$ is $\rm1788~kJ~mol^{-1}$. Then how can we calculate the enthaply of combustion of propanone? ...
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1answer
149 views

Which has maximum entropy

Which state has a higher entropy — the liquid–gas equilibrium or the gaseous state? I have learned that at equilibrium the entropy is maximised. But I also learned that the gaseous state has the ...
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3answers
62 views

Thermodynamics entropy and temperature

In thermodynamics, whenever heat is released from the system to the surroundings, temperature of surroundings remains unchanged but entropy increases. But entropy is a function of temperature. How is ...
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2answers
53 views

Does adding ice to sparkling mineral water extend the 'fizziness' of the solution before the drink goes flat?

To my understanding the carbonated beverage loses its $\ce{CO2}$ content as gas bubbles which gives the drink its 'fizziness'. The loss of $\ce{CO2}$ occurs due to the low solubility of carbonic acid ...
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Boiling of water does not involve temperature change, so why is there a change in internal energy during the process? [duplicate]

in an isothermal process, the value ΔT = 0 and therefore ΔU = 0 but during boiling if water at constant atmospheric pressure temperature doesn't change so why internal energy changes
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1answer
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Entropy change of a liquid [closed]

If the normal boiling point of a liquid A is $350\ \mathrm K$. $\Delta H$ at the normal boiling point is $35\ \mathrm{kJ/mol}$. Then entropy change at $350\ \mathrm K$ and $0.5\ \mathrm{atm}$ will be ...
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1answer
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VT graph thermodynamics

If we have one mole monoatomic ideal gas was taken through process AB as shown in the figure then ∆ S is positive and work is also positive but how can we find the value of work and heat absorbed as ...
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Thermodynamics PV graph [closed]

If an ideal gas is taken from state A to state B along a straight line path in PV diagram. So the work done by the gas in the process A to B exceeds the work that would be done by it if the system ...