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

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2answers
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A misunderstanding about the energy profile of reactions with a catalyst involved

All of us are aware of the importance of the catalysts in bio-chemistry. For a high school learner like me, catalysts ,and therefore, enzymes play a bridge-like role that connect high school bio to ...
2
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0answers
26 views

Ratio of MbO2/Mb in a satured solution of dissolved oxygen from dry air

What is the ratio of $\ce{MbO2/Mb}$ if the solution is saturated with air? Details of the question: \begin{align} &&\ce{Mb + O2 (aq) &-> MbO2}\\ &&\Delta G' &= ...
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1answer
20 views

Why is a reaction more favorable if one of the products is not soluble/sparingly soluble?

I have heard people go so far as to say that the "driving force" of a reaction is the formation of the precipitate. Why is this so? Whilst the process is almost certainly exothermic (I think - please ...
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0answers
18 views

Chemical Thermodynamics

In this pic, you can see the report for lab work. I did the labwork, and it is asking -to find delta H pr -? -delta H (theor)-? -error ? Please help me to find those
3
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1answer
36 views

Why is it necessary to consider infinitesimal changes in p,V,T for H,U and G given that they're state functions?

State functions such as $G$ only depend on the state of the system and are not dependent on the "path" that took the system to that state (which would be the case for work, for example, which is not a ...
8
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2answers
58 views

Why does N2 react with O2 to Form NO at high temperatures?

This also raises questions that I have about the Haber Process which produces ammonia ($\ce{NH3}$) from molecular nitrogen ($\ce{N2}$) and hydrogen ($\ce{H2}$). I have heard multiple times that bond ...
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0answers
16 views

Finding the thermodynamics of protein unfolding from temperature and absorbance using fluorescence spectroscopy?

I recently did an experiment on protein unfolding using a Perkin Elmer fluorescence spectrometer. The protein was $\alpha$-chymotrypsin. I was given this paper for my procedure. I am now trying to ...
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0answers
27 views

Determine the free energy when you have present in a 2.00 L flask: 8.0 atm pressure of NH3 (g) and 4.0 atm pressure of N2(g)

I don't know what to do to find the of free energy when you have present in a 2.00 L flask: 8.0 atm pressure of NH3 (g) and 4.0 atm pressure of N2(g). This is the table given: Cu(s) ΔHf° (kJ/mol) = ...
3
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1answer
31 views

How to derive the pressure dependency for the Gibbs free energy?

$$\mathrm{d}G=\left(\frac {\partial G}{\partial p}\right)_T+\left(\frac {\partial G}{\partial T}\right)_p$$ The above is an exact differential. Firstly what does this mean physically? (I hear about ...
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2answers
26 views

Thermochemistry problems?

Question 1: A compound A reacts according to the following hypothetical equation and has a molecular weight of 48.36 g/mol. 3 A (s) +B (aq) ––> 2 C (aq) ∆H° = ? A sample of A, weighing 0.152 g ...
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1answer
37 views

How to calculate the activation energy of diffusion of carbon in iron?

At room temperature, $298~\mathrm{K}$, the diffusivity of carbon in iron is $9.06\cdot 10^{-26}\frac{m^2}{s}$. At $573~\mathrm{K}$ the diffusivity is $1.66\cdot 10^{-15}\frac{m^2}{s}$. What is ...
4
votes
1answer
55 views

Phase diagrams (weird region)

On the left, there is a region for $\ce{MgO(ss)}$. I've been told such regions exist because stuff are not miscible. However, does that mean the composition axis on the bottom is a lie? Namely, ...
6
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1answer
305 views

What Causes there to be a Maximum Amount of Salt which can be Dissolved in Water?

When you add salt to water and stir, after a while the salt will no longer dissolve. Why is this?
4
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1answer
57 views

Do water hybrid cars really exist?

I have heard a few claims about water-fueled cars. Being a student of Engineering I totally understand that water-fueled cars (using electrolysis to generate Hydrogen) are nothing more than a hoax, ...
1
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1answer
21 views

What will happen to the entropy and free energy of the gasses when the partition is removed?

Consider a container of volume $ 5.0$ L that is divided into two compartments of equal size. In the left compartment there is nitrogen at $1.0$ $atm$ and $25 °C$; in the right ...
2
votes
1answer
51 views

Where does this equation for the activity in the gas phase equilibrium between N2, H2 and NH3 come from?

I have a question with Equilibrium Constant. I understand that for a reaction in equilibrium $aA +bB \rightleftharpoons cC +dD$ $$K_c= \frac{[C]^c[D]^d}{[A]^a[B]^b}$$ and $K_p$ is just using the ...
15
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4answers
4k views

Hypothetical: What happens to water as pressure increases to infinity?

I've asked a similar question here but the answer given shows the behaviour of water under general conditions. I'd like to know what the behaviour of water is like as pressures increase towards ...
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0answers
21 views

How can a melting and a freezing point of ice be the same [duplicate]

How can a freezing and a melting point of ice be the same ??
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1answer
30 views

Do liquid O2 and N2 form ideal solutions?

I suspect they do, but could not find data on this. (I mean at temperatures near those used in the distillation of liquid air.)
2
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3answers
164 views

Since the formation of diamond from Graphite is endothermic and the entropy decreases for this process, how is it possible to make diamond?

Surely G would always be positive and thus would make it impossible to make diamond. Clearly this is not the case. But how? Would an increase or decrease in temperature aid it's formation? I think a ...
3
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0answers
35 views

How can -G/T and -A/T be thought of as 'disguised' entropies?

I understand that entropy is defined as $\mathrm{d}S=\mathrm{d}q/T$ for a reversible change but I fail to see why $-G/T$ and $-A/T$ can be thought of as 'disguised' entropies. This is a question on my ...
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1answer
28 views

If $ds>=dq/T$ for a spontaneous change is $ds<=dq/T$ for a non-spontaneous change and is that even possible?

I am struggling with the concept of entropy but might be on the verge of understanding it. The Clausius inequality - $ds>=dq/T$ - is true for all spontaneous changes with the equality for ...
2
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2answers
55 views

What does the Clausius Inequality mean in thermodynamics? (entropy)

$$\delta S\ge\frac{\delta q}T$$ I don't understand how a quantity (the change in entropy in this case) can be greater than the very thing that defines it ($\mathrm{\frac{\delta q}{T}}$). Also ...
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1answer
37 views

Thermodynamics of Solid-Liquid

If you have an ice cube in water and the ice cube does not melt after reaching equilibrium with the water, does the water have temperature 0 degrees C?
2
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1answer
76 views

Difference between internal energy of combustion and enthalpy of combustion?

I am having real trouble understanding the first law of thermodynamics and I think the question, below, highlights most of my issues: 1) (a) A bomb calorimeter was calibrated by igniting a 0.825 g ...
3
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2answers
49 views

Why it is not possible to find absolute value of internal energy?

Today in thermodynamics lecture my teacher told that it is not possible to find absolute value of internal energy so we have to calculate change in internal energy. So my question is Why it is not ...
3
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2answers
65 views

Combustion in a bomb calorimeter: Am I overthinking?

To generalize the problem, I will just say: 5 gram of impure ethanol(or any other type of combustible material) is placed inside a bomb calorimeter where volume is constant, if the combustion ...
3
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1answer
39 views

Transfer of energy

After completing a lab for my chemistry class I am finding it difficult to find the initial temperature of an iron nail after being heated. Procedure of the lab went as follows: heat an iron nail, ...
3
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1answer
36 views

How will liquid nitrogen affect a steel instrument's ability to function?

I want to retrieve cryotubes from the bottom of a liquid nitrogen freezer without taking all the freezer racks out and draining the liquid nitrogen. I think I can accomplish this using a tool like ...
3
votes
2answers
68 views

If the equilibrium constant in a reaction is greater than 1 is it possible that there are more moles of reactants than products?

I'm wondering if this is possible because could there not be a situation in which the reactants were pure solids/liquids and would therefore not contribute to the value of k but still contain more ...
3
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3answers
65 views

Thermodynamics: Is Isolated system possible?

I have just started learning thermodynamics. I have learned that The system which is not able to exchange energy and matter on its own with surrounding is called isolated system. I wanted to know ...
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0answers
19 views

What is the non-ideal equivalent of mass action kinetics?

Starting from the equations of mass action kinetics, one may show that (for suitably chosen numbers $A_i$), the function $\sum_i x_i(A_i + \log x_i)$ is a Lyapunov function, i.e. it decreases over ...
3
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1answer
71 views

Conditions for spontaneity

So the two conditions for a reaction to be spontaneous are: tendency to achieve minimum energy tendency to achieve maximum randomness. Both these things are contrasting and the only way I see them ...
2
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3answers
78 views

Are these statements about change in enthalpy contradictory?

Just going through my thermodynamics chapter I came across 2 contrasting statements: Change in enthalpy=enthalpy of (products-reactants) at constant pressure and temperature. Change in ...
2
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1answer
36 views

Enthalpy(H) formula: what is the pressure volume product

$$\mathrm{H=U+PV}$$ Above is the formula for enthalpy- or, the sum of the internal energy and pressure volume product. $\mathrm{- P\Delta V}$ is work done by or on the system. But $\mathrm{PV}$, ...
0
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1answer
23 views

Bomb calorimeter and heat capacity of calorimeter

Can anyone describe the process through which we determine the heat capacity of calorimeter, for me? The formula is $q_{calorimeter} = C_{calorimeter} \times \Delta T$ The heat of bomb calorimeter ...
2
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1answer
245 views

Validity of Trouton's Rule

I would like to know under what circumstances is Trouton's rule obeyed by liquids and why certain systems i.e. substances may deviate from Trouton's rule. By the way I know what Trouton's rule is ...
2
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1answer
71 views

Why is the Standard enthalpy of formation of O2 and other reference forms of element zero?

Well, from what I know bonding releases energy. And does anybody know a source for finding the reference form of element at standard conditions?
2
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1answer
39 views

Concept of heat of reaction in a isolated system

One description of the concept is that heat of reaction (exothermic) is the quantity of heat that would given off to the surrounding by the product of a reaction if we allow the product to cool down. ...
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0answers
31 views

heat released from combustion of ethane

What will be the heat released when 4.42g of ethane is combusted at 298 K and 1 atm pressure?
2
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1answer
79 views

What is the entropy of mixing of two ideal gases starting out with different pressures?

The entropy of mixing of ideal gas is given by this equation: $\Delta S_{mix} = -nR(x_1\ln x_1 + x_2\ln x_2)$ Does this equation works only when the initial conditions of both compartments are at ...
3
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1answer
194 views

Why do we use dG < 0 to describe a spontaneous process?

With something like a reaction or phase change, all sources use the criterion that $dG < 0$ for the reaction to be spontaneous and then substitute an appropriate expression for $dG$ to the specific ...
3
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1answer
40 views

SI Units for Isothermal Incompressibility and Specific heat capacity at constant volume

I am looking for the SI units of Isothermal Incompressibility and Specific heat capacity at constant volume. What I found was that Isothermal compression was measured in $\frac{m^2}{N}$ so I'm ...
0
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1answer
59 views

Proof of kinetic energy equation

Is there a way to prove that $\frac{1}{2} mv^2 $$= \frac{3}{2}RT$ The first one is kinetic energy and the second is the average kinetic energy. Can this be proved by component of velocity.
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1answer
185 views

A thermos bottle containing milk is shaken vigorously

I have a conceptual physical chemistry question here. A thermos bottle containing milk is shaken vigorously. Consider the milk as the system. Will the temperature rise as a result of the shaking? ...
0
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1answer
66 views

Finding the equilibrium temperature between two substances in a constant pressure calorimeter

I need to find the temperature two things equilibrate to in a constant pressure calorimeter given only their specific heats, masses, and starting temps. The only thing I know for specific heat is ...
3
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1answer
48 views

Relation between thermodynamic reversible process and reversible reaction

I know it seems to be a weird question. But for long I have been thinking whether there is any relation between thermodynamic reversible process and reversible reaction. Do they have any connection ...
2
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1answer
130 views

A contradiction, probably from confusion

All things in nature tells us that high entropy is easier to happen. But then why does it takes energy to break bonds, in order to achieve high entropy. Any thing in gaseous state has higher ...
3
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1answer
52 views

Significance of Kinetic Velocities?

In the concept of Kinetic Molecular Theory we have rms(root mean square), avg(average) and mp(most probable) velocities. I understand the concept well. But my question is why do we have three ...
8
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2answers
132 views

How can a protein folding transition state have zero lifetime?

I'm doing a module on my Biochemistry course looking at protein folding, and in a discussion of [folding] transition states I was a little confused at the thought of a zero-lifetime transition state - ...