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

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Nature of spontaneous reactions

The definition of spontaneous process states that "A spontaneous process is an irreversible process and maybe reversed by some external agency" So, can we say that all spontaneous reactions are ...
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Derivation of a formula

I have a formula for finding the final temperature in an irreversible adiabatic expansion. $$T_2=\left[\frac{C_v+(\frac{P_2}{P_1})}{C_p}\right]T_1$$ where $T_1$ is the initial temperature. $C_v$ and ...
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Can lattice enthalpy only be determined by the Born-Haber cycle?

Since we are able to determine the enthapy of formation experimentally, why it is impossible to determine the lattice enthalpy directly by experiment?
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Correlation between the virial coefficients and a & b in the corresponding Van Der Waals equation of state

I don't know where to begin with this question. A function f(x) can be expressed as a special power series called the Taylor expansion. The common expansion is $(1-x)^{-1}=1+x+x^2$ Note that the ...
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How fast will hydrazine boil out of a tube into a vacuum?

For context I'm talking about ISEE-3 and how long it would take to dump the now useless and hazardous fuel it still carries. Given a heated tank of hydrazine (somewhere near $0~^\circ\mathrm{C}$) ...
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Is sign convention for delta H and enthapy change of a solution different?

I have got some confusion . In the Ncert Chemistry Tb , it is given in bold that $\Delta H$ is negative for exothermic reactions which evolve heat during the reaction and $\Delta H$ is positive for ...
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Why is pressure negative in force and work

The equation to measure work is $$w=F\cdot D$$ However, the equation for force is $$F=(-P \cdot A)$$ Plugging this into the work equation we have: $$w=-P\cdot A\cdot D$$ My question is, why is ...
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Can the thermodynamic information of a compound be calculated or must it be found emperically?

Do attributes such as heat of formation have to be found through experimentation or can they be calculated based on the attributes of the bonds and the atoms involved?
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Why is carbon monoxide the product in reactions that produce high flame temperatures?

I was looking at substances that produce the highest flame temperatures upon combustion. I note that the equations for combustion are producing carbon monoxide rather than carbon dioxide. $\ce{(CN)2 ...
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Calculating amount of ice required for heat loss

Question: Given $400.0\ \mathrm{g}$ of hot tea at $80.0 °\mathrm{C}$, what mass of ice at $0 °\mathrm{C}$ must be added to obtain iced tea at $10.0 °\mathrm{C}$? The specific heat of the tea ...
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76 views

Why is mercury used in thermometers?

I know it expands when hot and grows compact when cool (that's about all I know), but I suppose many other substances do, too. Also, and excuses for my ignorance, what the term used to describe the ...
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Thermodynamic dependency of the rate of reaction

On one hand, the larger is the reduction potential of the chemical reaction and the smaller is its activation energy the larger would be the rate of reaction, on the other hand the rate of a reaction ...
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Is 4-nitrobenzaldehyde or 4-aminobenzaldehyde more likely to be hydrated?

Of 4-nitrobenzaldehyde and 4-aminobenzaldehyde, which has the higher $\ce{K_{eq}}$ of hydration? $\qquad \qquad$ Steric factors can likely be ignored in this problem since we are dealing with ...
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2answers
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Determining if reaction is endothermic or exothermic using equilbrium constant

For the following reaction: $$W_{(s)}+4\,Br_{(g)}\rightleftharpoons WBr_{4(g)}$$ At 900 K, $K_{p}=100$ and at 2800 K, $K_{p}=5$. At higher temperatures, the equilibrium has shifted towards the ...
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71 views

Why are metal oxides generally more stable than their corresponding elemental forms?

Why is the oxidation of certain metals such as iron favorable from a thermodynamic standpoint? What is it about these metal oxides that makes them inherently more thermodynamically stable than their ...
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Moist Chlorine & Hydrogen Psychrometric or Mollier Chart

In our electrolysis of brine, $\ce{Cl2}$ and $\ce{H2}$ are produced as gaseous products along with aqueous $\ce{NaOH}$. In this scenario I require what amount of maximum moisture can $\ce{Cl2}$ and ...
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70 views

The difference between heat of reaction at constant pressure and that at constant volume

If supposing the kp value of a reaction is 10 Atm at 300K and 4atm at 400K. Then how can we say that the difference between the heat of reaction at constant pressure and that at constant volume is RT ...
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What is the cause for thermodynamic reversible and irreversible process?

My book defines Thermodynamic irreversible process is defined as the process in which the changes take place rapidly, instead of occurring in successive stages with infinitesimal changes in ...
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Why is ΔE described as Q-W and Q+W in different contexts?

Depending on the textbooks looked at, the energy change is described as either Q+W or the signage is changed to Q-W. Which is correct? Is it solely context dependent? Could anyone explain the ...
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Can a solid and liquid be miscible?

To be specific, what I mean is: is the following situation possible? At given temperature T, there are two substances, X and Y, such that pure X is a solid, pure Y is a liquid, and X and Y mix to form ...
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How to calculate the heat absorbed by a reversible process?

Given a nonideal substance inside a box with diathermal walls, the pressure is increased reversibly. How do you calculate the heat absorbed? I assume we use dE = dq + dw = dq - pdV => dq = dE + ...
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Problems with thermodynamic derivatives

How is the following true? $$\left ( \frac{∂S}{∂P} \right )_{T}=\frac{-C_{P}}{T}\left ( \frac{∂T}{∂P} \right )_{S}$$ I know that $$C_{P}=T\left ( \frac{∂S}{∂T} \right )_{P}$$ which means the ...
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Is superglue a good thermal insulator?

How good of a thermal insulator is superglue compared to other materials like ceramics, plastics, and metals? I know this might not seem like a chemistry question, but I was hoping someone here could ...
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What is the correct definition of the Gibbs free energy of activation?

Is the following correct? Gibbs free energy of activation is used in energy profiles where the stabilities of the species are expressed as changes in Gibbs energy, while the activation energy Ea ...
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Why is the equilibrium constant given in litre per mole?

At $800\:\mathrm{K}$ a reaction mixture contained $0.5\:\mathrm{mol}$ of $\ce{SO2}$, $0.12\:\mathrm{mol}$ of $\ce{O2}$ and $5\:\mathrm{mol}$ of $\ce{SO3}$ at equilibrium. $K_c$ for the equilibrium ...
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Why is there sulfur in black powder / gun powder?

Black powder is composed of charcoal, sulfur and a nitrate salt. The charcoal and sulfur serve as fuel and the nitrate is the oxidizing agent. However, wouldn't it be cheaper to leave out the ...
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Name the equation $\Delta G=\Delta G^{\circ}+RT \ln Q$

As the title states, what is the name of the equation $$\Delta G=\Delta G^{\circ}+RT \ln Q$$ My textbook does not explicitly state the name and I could not find anything on google.
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3answers
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How do breaking chemical bonds turn into kinetic energy

I’m trying to understand how breaking chemical bonds turn into kinetic energy. If AB is a chemical which breaks into A and B which zip away from each other, is it because when the bond breaks they ...
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1answer
47 views

What can we say about the Gibbs free energy if it decreases or not?

[Sorry if the question looks trivial but I have thought about it for days and red a number of books all with no success.] In almost every thermodynamics book that has something to say about chemical ...
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Calorimetry | Heat produced VS Change of enthalpy

There are two questions on the same test paper. Calculate the amount of heat energy, $q$, produced in the reaction Find the change of heat ($-q$). I'm not sure whether or not they mean the same ...
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Synthetical formation of diamonds

As everyone knows a diamond won't last forever. It will eventually turn into a graphite over a long period of time, as the free energy of graphite is lower than that of diamond, hence making the ...
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How can I find the heat that will be released in kJ per gram for the reaction of Al with Fe2O3?

Find the heat that will be released in kJ per gram when aluminium ($\ce{Al}$) reacts with $\ce{Fe2O3}$ as follows : $\ce{2Al(s) + Fe2O3(s) → Al2O3(s) + 2Fe(l)}$ the information given is: $\Delta H ...
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∆Enthalpy of diatomic molecules

Question: The reaction between hydrogen and oxygen to yield water vapor has $\Delta{}H^\circ = -484~\mathrm{kJ}$. How much $PV$ work is done, and what is the value of $\Delta{}E$ in kilojoules ...
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What is the name of the formula ΔE = q + w?

What is the name of this formula? Google could not provide me with an answer. $$\Delta E=q+w$$
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In what ways does the transfer of heat affect bond stability?

It is to my understanding that certain amount of joules may change an element's/compound's physical state given a certain temperature. How does a certain added number of joules affect the orbital of a ...
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Relating Thermodynamic & Transport Properties to Electrochemical discharge curve

What are the fundamental thermodynamic & transport properties that the discharge cycle of a rechargeable battery with an intercalating cathode (like Li-ion) should depend upon? The few that I ...
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1answer
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Is the activity coefficient always a constant?

The activity of a species $i$ is defined as $a_i = e^\frac{\mu_i-\mu_i^\ominus}{RT}$, with $\mu_i$ the chemical potential, and $\mu_i^\ominus$ the chemical potential under standard conditions. Very ...
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How do you calculate enthalpy for a reaction at non-standard conditions?

I understand how to calculate the change in enthalpy and entropy for a reaction in standard conditions, but is there a way to calculate these values at non-standard conditions? Also, is there any way ...
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129 views

Steric Hindrance and Bronsted Basicity

Does steric hindrance affect Bronsted basicity? I understand that basicity is a thermodynamic quality. Not a kinetic factor. So it doesn't matter if it takes a million years for the proton to reach ...
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calculate the amount of energy in KJ necessary to convert 346 g of liquid water from 0 C to water vapor at 182 C

Calculate the amount of energy in $\mathrm{KJ}$ necessary to convert $346~\mathrm{g}$ of liquid water from $0~^\circ\mathrm{C}$ to water vapor at $182~^\circ\mathrm{C}$. The correct answer is ...
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1answer
574 views

Does ice melt faster when submerged in water?

Suppose you have a container with a drain at the bottom full of frozen H2O which you leave a room temperature to melt. Will the ice melt faster if you drain the water as it melts? I would expect that ...
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Equilibrium Graphs

What if I2 and H2 began at the same concentration - then do we start at the same point? ... or is it acceptable to start at different concentrations...
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Equilibrium Practical Discussion Help

I understand the theory, but am struggling to answer the following discussion questions: (i) Why isn't this represented by: Fe3+ (aq) + 3 SCN- (aq) <-> Fe(SCN)3 (aq) Why do we dilute the ...
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On spontaneity of a redox reaction

Suppose we have a redox reaction and we want to see in what direction the reaction is spontaneous. We do this by comparing the standard reduction potentials of the sub-reactions available in the main ...
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Kinetic and Thermodynamic Stability

My prof noted that if the two components of any ionic compound undergo a large extent reaction with each other, then the substance CANNOT exist as a pure substance. For example, consider ammonium ...
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Does having constant pressure imply a temperature change? Why isn't the volume needed to calculate the final temperature and energy?

Calculate the final temperature and the change in internal energy when $500\:\mathrm{J}$ of energy is transferred as heat to $0.900\:\mathrm{mol}$ $\ce{O2(g)}$ at $298\:\mathrm{K}$ and ...
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Can compressed CO2 sprayed onto a hot mass/liquid be an effective means to cool it?

I thought the answer was obvious, but endless google searching has revealed nothing but speculation and people who have completely conflicting opinions. Some people say CO2 absorbs no heat, others say ...
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Greater entropy: an atom or macromolecule?

A question that appeared on my last chemistry exam was : Which of the following has greater entropy A) An atom B) A macromolecule The question doesn't specify anything else(i.e. type/size ...
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Determine the ΔH for the reaction in kJ/mol of ethanol?

A $1.000~\mathrm{g}$ sample of ethanol, $\ce{C2H5OH}$, was burned in a bomb calorimeter whose heat capacity had been determined to be $2.71~\mathrm{kJ/C}$. The temperature of $3.000~\mathrm{kg}$ of ...
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Why do ionic substances with higher lattice energies tend to be less soluble in water than substances with lower lattice energies

I understand that that energy is required to overcome intermolecular forces holding solute particles together in the crystal but I don't understand how this relates to lattice energies and its ...