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

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What kind of equilibrium constant we use for Gibbs free energy and Van't Hoff equation?

We know that Gibbs free energy is same as negative of 8.314 times temperature in Kelvin times natural logarithm of equilibrium constant, or: Then, we also know Van't Hoff equation, like: (R in ...
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1answer
18 views

Why is adiabatic process isentropic?

I have read that adiabatic process is isentropic because there is no heat exchange in an adiabatic process and thus no change in entropy. But my question is - Even in adiabatic process, work can be ...
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1answer
14 views

Thermochemistry Delta T?

An equation of heat is s * m * delta T. I know that delta T can be in either Celsius or Kelvin. However, one thing that confuses me is how the units cancel if delta T is in Celsius. How does this ...
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1answer
20 views

Change in pressure or volume of molten salt

I am doing a project in which I fill a cylinder with a volume of $636cm^2$ (made of stainless steel) with molten salt: 60% Sodium Nitrate ($NaNO_3$) and 40% Potassium Nitrate($KNO_3$). The container ...
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2answers
29 views

Heat capacity question

The specific heat capacity of liquid water is $4.18 \, \text{J} \, \text{K}^{-1} \, \text{g}^{-1}$. Calculate the energy required to heat $1.0 \, \text{mol}$ of water from $298 \, \text{K}$ to $363 \, ...
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31 views

Does covalent character increase or decrease bond strength?

I am a bit confused on one hand covalent character increases the bond dissociation enthalpy (i.e. more energy is needed to be put in) and on the other it lowers the melting point of Al2O3 to a value ...
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26 views

What happens to water under high pressures without possibility of escape?

Knowing very little about the nature of water, wondering how it might behave at the centre of a planet or centre of an another massive gravitational body. Could water take such pressures or might it ...
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1answer
20 views

How to estimate the dielectric constant of a liquid?

Are there any approximate relationships between the (static) dielectric constant of a liquid and properties of the individual molecules? For example, suppose I know the polarizability and dipole ...
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1answer
24 views

What is the energy change of ethene reacting with hydrogen gas?

$\ce{CH2CH2(g) + H2(g) -> CH3CH3(g)}$ Using this table, source: http://www.kentchemistry.com/images/links/Kinetics/TB08_003.GIF ...
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34 views

Covalent character and ionic dissociation enthalpy?

I am a bit confused does covalent characteristic within a bond increase or decrease its strength as i have found two counter examples: firstly covelent character increases the enthalpy of dissociation ...
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1answer
83 views

Conceptualizing Multiple Equilibria

Take the reaction: $$ (1) \; \ce{A + B <=>X + Y}, \; K_1=\frac{[X][Y]}{[A][B]} $$ Now assume that X isomerizes to Z according to: $$ (2) \; \ce{X <=> Z}, \; K_2=\frac{[Z]}{[X]} $$ We can ...
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1answer
43 views

Why isn't ΔG equal to zero for this equilibrium reaction?

In the reaction $\ce{E(g) <=> P(g)}$ at 25°C, equilibrium is reached when the pressure of the product is 0.100 that of the reactant. What is $\Delta G$ in joules? Using $\Delta G = \text{RT} ln ...
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2answers
82 views

T is the temperature of what?

In equation of gibbs free energy change $\Delta G = \Delta H-T\Delta S$,is T system's or surrounding's temperature? Edit:Oh sorry I am not clear earlier now I get clear question.I know we have to ...
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1answer
89 views

Hess's Law/Enthalpy of Formation problems?

How do I solve problems where I'm asked for $\Delta H^\circ_f$ and given $\Delta H^\circ_f$ values for equations with the involved elements? For example: Find the $\Delta H^\circ_f$ of the following ...
2
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1answer
27 views

How to trace an Energy Time diagram?

I'm looking for data to create a simple graph of an exothermic or endothermic reaction but can't find any. Could someone help me with some enough data to create a Energy(time) simple graph.
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2answers
186 views

Approximate time for pure water pH to equilibrate in open air?

I'm a complete non-chemist, so I don't know how to calculate this, or even what to google for (my searches yielded esoteric research papers). I'm doing some hobby experiments, and I'd like to know ...
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2answers
53 views

What is the heat required to melt this ice cube?

I am need of help with this question: 18 g is one mole. (a) I guess you meant to 0 degrees C? So, 70.391 x 20 = 1408 J (b) 6.01 kJ (c) 180 g is 10 moles. It would take about 15kJ to cool all of ...
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1answer
48 views

Why does the equilibrium constant depend on the temperature but not on pressure and concentration?

According to my textbook (and intuitively) certain changes when the aforementioned 3 variables are altered occur in accordance with Le Chatelier's Principle. However, what I don't understand is what ...
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1answer
35 views

Standard reference for thermodynamic properties for octane

where can I find thermodynamics properties for octane at saturated Temp.$T_s$? I need this properties or where can i find all ? $$liquid-density=\rho_l=?$$ $$vapor-density=\rho_v=?$$ ...
3
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1answer
37 views

problem with partial pressures

This is a question I solved in class: At 35 degrees, $\ce{N_2O_4}$ is 15% dissociated in a flask at a pressure of 1.2 atm. Calculate $K_p$ Equation: $$\ce{N_2O_4(g)<=>2NO_2 (g)}$$ ...
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25 views

Equations to Support Argument in Protein Physics

I'm studying for a test in Protein Physics and my lecturer says we should know why proline and glycine are not seen in alpha helices and that we should use equations in order to support our arguments. ...
2
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1answer
36 views

Why is ionization energy measured in gaseous phase?

When I looked up the definition of ionization energy, it says:- it is the energy required to remove one electron from the shell to infinity in an atom in gaseous state. Why is it measured in ...
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4answers
129 views

How could I create a machine that as rapidly as possible creates greenhouse gases from air?

For a very large-scale project, I am trying to create a greenhouse gas demonstration device, which rapidly produces greenhouse gases from atmospheric air using only electricity, or any chemical ...
3
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1answer
63 views

Thermodynamic stability of benzene ring

In learned that when benzene undergoes hydrogenation, $208KJ$ of energy is given off and thus $152KJ$ less energy than what would be given off if Kekule's structure was correct. My confusion is that ...
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30 views

Is there a function for finding the pressure of an explosion? [duplicate]

Is there a function $P(t)$ that lets you calculate the pressure of an explosion: $\ce{2H2 + O2 -> 2H2O}$ given these variables? $V \text{ (volume)}$ $n \text{ (moles of hydrogen and oxygen ...
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48 views

About the T-S diagram

Suppose we have a T-S diagram of some vapor thermodynamic cycle , say the rankine cycle , and we are interested for example in the composition of the liquid and the vapor in the middle of the ...
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1answer
55 views

Chemical Potential of Idea gas?

Let's say we have a mixture of different ideal gases. I found that the chemical potential of a single component of the mixture is $$\mu_{i}=g_{i}^{0}+Ln(\frac{f_{i}}{P_{ref}})$$ where $f_{i}$ is the ...
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1answer
30 views

Polymers with no molecular mass distribution?

What sort of ideal conditions are required - theoretically - to conduct polymerization reactions to make all the macromolecules end up with exactly the same molecular mass, just like the products in ...
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1answer
53 views

Enthalpy of Zinc and Sulfur Reaction

I was working on my homework which was to write a description of what would occur if zinc and sulfur reacted and what steps would a scientist have to make in order to make them react. When I ...
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1answer
48 views

Thermal decomposition of calcium carbonate

Thermal decomposition of calcium carbonate. In general, we heat $\ce{CaCO3}$ to temperature of approximately 825°C it decomposes into calcium oxide and liberates carbon dioxide gas:* $$\ce{CaCO3} ...
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1answer
23 views

Relation between c and compressibility

We know that $c^2=\frac{\partial p}{\partial ρ}$ The adiabatic compressibility is defined as: $\beta_S=-\frac{1}{V}\frac{\partial V}{\partial p}$ such that the subscript "S" stands for "adiabatic" ...
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1answer
53 views

How to calculate ring strain energy

Series A and B below can be viewed in two different ways to annulate an ethano bridge onto four-, five-, and six-membered rings. Using the $\Delta H_f^\circ$ values given (in kcal/mol), how can one ...
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1answer
58 views

cooling/refrigeration essentiality for carbonated softdrinks

How does cooling/refrigeration help in maintaining the taste and shelf life of food products, especially CSD (Carbonated Soft Drinks)? For example, chilled drinks have a nicer taste than a normal ...
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2answers
70 views

How well (or poorly) does natural leather insulate?

What is the general thermal conductivity of animal skin leather? I understand there are many different animal's skins (cow, sheep, buffalo, deer, pig), but in general, does natural leather insulate ...
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1answer
67 views

Thermodynamics Problems!

A cylinder, 0.5m long and of cross section S, closed at each end is fitted with a smooth thermally insulating piston, so as to contain gas in each end A and B. Initially, the piston is in equilibrium ...
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1answer
52 views

Ideal gas derivations

For an ideal gas, how can someone obtain this: $$ \bar{V}dP = RdT- P \bar{dV}$$ from which it can de deducted, that for a constant temperature $$ \frac{dP}{\bar{dV}} = -RT $$
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1answer
41 views

Thermodynamics and equilibrium constant

I just wanted to make sure how we can know whether it is $K_c$ (equilibrium constant of concentrations) or $K_p$ (equilibrium constant of pressures) which "comes out" of the equation, $\Delta G^o= -RT ...
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1answer
53 views

Which of these thermodynamic relationships is true for a system at equilibrium?

Which of the following is true at equilibrium $$T \Delta{S} = \Delta{H}$$ $$T \Delta{s} = \Delta {G}$$ I think it's the first one but I just wanted to be sure.
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2answers
78 views

How do I distinguish internal energy and enthalpy?

I am finding it hard to distinguish between the two. Can someone explain the two terms and the difference between them? I tried learning from Wikipedia, but it said for both the above terms that it ...
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0answers
43 views

How to estimate reaction products of competitive binding?

I have an two reactions, $A + C \rightleftharpoons AC$ $B + C \rightleftharpoons BC$ I'd like to estimate relative steady state proportions $\frac{[BC]_{SS}}{[AC]_{SS}+[BC]_{SS}}$ and ...
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1answer
833 views

Is the reaction thermodynamically favored or not?

$\ce{CO(g) + 2H2(g) +O2(g) <=> 2CH3OH(g)}$, $\Delta H=-128 kJ/mol$ $\Delta S=-409.2 J/mol*K$ Determine if the reaction if thermodynamically favored. I just wanted someone to see if my logic ...
2
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1answer
828 views

Enthalpy change in an adiabatic system

This is a Chemistry GRE Question. Which of the following must be true for adiabatic processes? $C_v = C_p$ $\Delta H = 0$ $\Delta U = 0$ $\Delta S = 0$ $q = 0$ The answer is q = 0. From what I ...
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113 views

Is there a general consensus on the causes of the $\alpha$-effect?

There have been various explanations posited for the $\alpha$-effect. It is currently in the list of unsolved problems in chemistry on Wikipedia, but, due to a lack of references to that effect, I'm ...
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1answer
146 views

how is the relation between Gibbs free energy and cell potential?

First of all what is exactly Gibbs free energy in regards to an electrochemical process? How can we visualise it? How does Gibbs free energy change in an electrochemical reaction? How is it related to ...
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1answer
47 views

Styrofoam cup calorimeter? [closed]

50.14 g of HCl react with 0.50 g of MgO. The formula of the reaction is: 2HCl + MgO -> MgCl2 + H2O Ti of HCl = 20.6 degrees C. It's in a styrofoam cup. Then MgO is added. Tf = 27.3 (after the ...
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26 views

Calculating photolysis time of AgF

How can I theoretically predict the time needed to photolyze n moles of AgF? (with UV) (this is not a homework question) The photolysis of AgF requires UV light - but I don't know which wavelength ...
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1answer
109 views

Is it possible to make liquid nitrogen with a bottle of CO2 gas and a freezer?

I really want to make liquid nitrogen(or oxygen) without using dry ice, a specially made freezer, or other chemicals. I have a mixture of some sponges, rotten grass, sugar and water, which makes ...
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1answer
83 views

How do I determine the temperature at which a dissolved substance evaporates?

I would like to understand the temperature at which a substance will vaporize when dissolved in a liquid. I have researched this online for hours, but haven't found a conclusive answer. Is it the ...
2
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1answer
95 views

A chemistry approach to environmentally friendly yoga mats… NBR, NR, TPE, PER [closed]

I'm currently seeking your expertise while creating a line of environmentally friendly yoga mats, and I apologize in advance if any chemistry knowledge of mine has been absent since college and I lack ...
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0answers
24 views

What are the products formed by a typical wood fire? [duplicate]

What are the products formed by a typical wood fire? I tested the ash from my fireplace and found it to be on the acid side. While this question has been partially answered in answers to another ...