The study of chemical systems using the laws and concepts of physics. This usually requires the techniques of thermodynamics, statistical mechanics and quantum mechanics.

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Equilibrium Problem Involving Solids: Faulty?

I am convinced that this is a faulty problem: $\ce{2 Cu + S -> Cu2S}$ For the reaction above, $\Delta H$, $\Delta S$, and $\Delta G$ are all negative. Which of the substances would ...
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13 views

Reducing water content of gypsum/plaster powder. I'm having caking problems

I have a gypsum/plaster of paris powder that I need to pass through a mesh filter. However, the powder keeps on caking at the mesh filter due to what I suspect is the high water content. The powder ...
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22 views

Fire a safety matches with solid chemical [on hold]

Is it possible to fire a safety matchstick with any solid chemical kept 3-4 inches away? If possible please tell me the chemical or combination of chemicals Trying to self ignite the match stick, ...
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18 views

A problem from ionic equilbrium [on hold]

The solubility product of Calcium hydroxide at 298 K is 0.0000442.A 500 ml of saturated solution of calcium hydroixde is mixed with equal volume of 0.4 M sodium hydroxide.How much calcium hydroxide in ...
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14 views

Im wondering how to calculate winstrols half life? [on hold]

The reason i ask is because a horse i have had winstrol in its system when tested in serum. The horses level was 315pg/ml. He had 5ccs of 250mg/ml Half life is 24 hours on the substance.
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1answer
36 views

Volcano plots: How is the data fitted?

When studying about catalysts I normally come accross volcano plots like the one shown below: What confuses me is how are the two lines fitted, how do you determine what points to include and what ...
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26 views

Why is ionisation energy defined for gaseous species? [duplicate]

Most high school and college textbooks usually define the first ionisation energy as such: The first ionisation energy is the energy required to remove 1 mole of electrons from one mole of ...
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1answer
27 views

A doubt in chemical equilbrium

say we have a reaction N2O4 reversible 2NO2 for this reaction,if initial number of moles of N2O4 is 'a' can we write t = 0 a - at equilbrium a-x 2x similarly can we do the same for pressure? i.e. ...
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18 views

Crystallisation [on hold]

A tank holds 10,000 kg of a saturated solution of sodium hydrogen carbonate at 60 degrees Celcius. You want to crystallize 500 kg of sodium hydrogen carbonate without any accompanying water from this ...
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46 views

Gibbs Free Energy and entropy of the universe

I'm having a little bit of trouble after putting alot of thought into the relationship between entropy of the universe and Gibbs Free Energy. Both are used to predict spontaneity, but from my ...
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2answers
45 views

A problem from thermodynamics

I am trying to do the following problem: Freezing of water at $273~\mathrm K$ and $1~\mathrm{atm}$ Which of the following is true for the above thermodynamics process? p) $q=0$ q) ...
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13 views

Stoichiometry Question [on hold]

This is a basic stoichiometry question but I still can't figure it out. 50 g of a metal carbonate on heating produces 30 g of its oxide. What is the equivalent mass of the metal? I asked my ...
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1answer
43 views

What is the difference of molar volume between dissolved 35Cl- and 37Cl-?

Im am geochemist, dealing with isotopes such as 35Cl and 37Cl. For some model I'm trying to make I need to be able to estimate what is the difference of partial molar volume between dissolved 35Cl ...
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1answer
74 views

Doubt regarding the second law of thermodynamics [closed]

$$\frac{q_{rev}}{T} = \Delta S$$ Here, what does $\Delta S$ signify? Does it mean the change in entropy of the system or the surroundings? How are the entropies of the system, the surroundings, and ...
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8 views

is it possible to use a luminescent chemical in a refrigeration system to detect small refrigerant leaks?

I know there is a flourescent chemical that can be added into refrigeration systems to identify refrigerant leaks but they have to be large leaks where oil is actually leaking from the system, my ...
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21 views

Alcohol rhodium interaction [closed]

I accidentally used 70% rubbing alcohol to clean earrings that I thought were sterling silver but were actually rhodium. It turned white. I tried to run water on them and run with my finger, but it ...
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1answer
51 views

Understanding effect of ph on solubility of salt

In the following picture why Ksp is not simply S2- ? Why is f included with one species only? Please explain the last part. What does f represent and why it is used in molar solubility?
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26 views

Application of ideal gas law equation [closed]

I'm given this problem Total number of moles of oxygen atoms in 3 litres of $O_2$ (g) at 270°C and $8.21$ atm are: I know that I can simply use PV $=$ nRT and just by plugging the values I can get my ...
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25 views

Unit cell question on determining compound stoichiometry of KCoS?

For 5(a) and 5(c), how are we determining that the answer is K4CoS4? I keep counting it and getting K2CoS2. We know that the K and the S ratio must be 1:1, but how can we count the Cobalt? . ...
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3answers
43 views

How is mean square displacement defined in Brownian motion?

I am trying to calculate mean square displacement (MSD) of water in a simulation to calculate its diffusion coefficient. However I am little confused on its exact form. Can anyone please explain it in ...
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28 views

Question on Mole Concept [closed]

A compound contains 8% oxygen and 4% sulphur. What is the minimum molecular weight of the compound? Please Explain.
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20 views

How to Identify solvent in this problem?

this was the question : "An antifreeze solution is prepared from 222.6 g of ethylene glycol and 200 g water.calculate molality of the solution" I solved it considering ehtylene glycol as solvent as it ...
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28 views

Temperature for certain vapor pressure of diethyl ether [closed]

At what temperature would diethyl ether have a vapor pressure of $250\ \mathrm{mmHg}$, if we are given that at a pressure of $401\ \mathrm{mmHg}$, $T = 18\ \mathrm{^\circ C}$ and $\Delta H = 26\ ...
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31 views

“Reacts most vigorously”

What is meaning of "Reacts most Vigorously" Is it related to Thermodynamic aspect or Kinetic? Like for example if we are given that A reacts with C more vigorously than B reacts with C. Then which ...
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16 views

Doubt on valence factor (n factor) 1

Can n factor be a non-natural number ? Will it be non-natural number in reactions involving non stoichiometric compounds ?
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9 views

A sample of wustile (Fe)xO contain one Fe(III) for every 3 Fe(II) then the value of x will be? [closed]

i know this question involves equalizing charges but still I m not getting a correct answer
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1answer
42 views

Freezing Point Depression Problem

Assuming an ideal solution, which of these 0.10 M solutions would have the least freezing point depression? $\ce{HCl}$ $\ce{NaBr}$ $\ce{KNO_3}$ $\ce{MgSO_4}$ They all produce ...
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13 views

Low temperature evaporation of EtOH in Propylene Glycol / EtOH mixture

If I have a mixture of approximately 90% Ethanol and 10% Propylene Glycol, but I am restricted to not allowing the mixture to reach above 40 degrees C, what is the best method to fully evaporate the ...
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1answer
22 views

Which reactions are more temperature sensitive, the ones with higher Ea or the ones with lower Ea and why?

I wasn't able to find much useful content on googling it, however on doing the math i came to a conclusion that the ones with higher Ea are more sensitive to increase in temperature. But why is it so? ...
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1answer
23 views

Determining the temperature at which 90% of the reactants in a equilibrium have reacted

I have the following problem I am stuck on, specifically the last bit (iii). The first parts are fairly trivial and I have arrived at the following equation to determine the temperature: ...
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13 views

How do you find mass percentage composition based on molality?

You take $20.0~\mathrm{g}$ of a sucrose and $\ce{NaCl}$ mixture and dissolve it in $1.0\ \mathrm{L}$ of water. The freezing point of this solution is found to be $0.426~\mathrm{^\circ C}$. Assuming ...
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20 views

Microarray SPR imaging vs “regular” SPR?

Background: I am taking a biochemistry course, and we have had some basic introduction to surface plasmon resonance (SPR). I don't have a very strong background in biophysical chemistry. Task: I am ...
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11 views

Chemisorption vs Physisorption?

What is the fundamental difference between chemical adsorption and physical adsorption. Why do some compounds chemisorb and others physisorb?
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26 views

Dimerisation effect on distribution ratio?

The question reads: "Carboxylic acids (RCOOH) form dimers in solvents of low polarity such as benzene and carbon tetrachloride. Using suitable equations, explain the effect of association on the ...
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23 views

How do you find mass percent composition based on molality?

You take $20.0~\mathrm{g}$ of a sucrose and $\ce{NaCl}$ mixture and dissolve it in $1.0\ \mathrm{L}$ of water. The freezing point of this solution is found to be $0.426~\mathrm{^\circ C}$. Assuming ...
3
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1answer
61 views

How to calculate pH of a solution when H3PO4,NaH2PO4,Na2HPO4 and Na3PO4 are mixed together in certain amounts to form a solution?

How to calculate pH of a solution when $\ce {H3PO4}$ ,$\ce {NaH2PO4}$,$\ce{Na2HPO4}$ and $\ce {Na_3PO_4}$ are mixed together in certain amounts to form a solution? I know how to calculate pH when ...
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13 views

How to calculate the gas pressure of HCl over a saturated CuCl2 solution

I have a concentrated solution of $\ce{CuCl2}$ ($<200~\mathrm{ml}$, surface area $2100~\mathrm{cm^2}$). I saw a note about protecting metal equipment from $\ce{HCl}$ attack in the room ...
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1answer
117 views
+50

How is the association/ dissociation constant derived?

I came across the following formula to find the association of a solute in particular solvent. Suppose the concentration of the solute given in water (or in some other solvent in which it does not ...
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35 views

Why is the melting point of magnesium anomalous? [duplicate]

The melting and boiling points for the Group II elements are as follows: $$\begin{array}{ccc} \text{Element} & \text{Melting point / }\mathrm{^\circ C} \\ \hline \ce{Be} & 1289 \\ \ce{Mg} ...
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1answer
88 views

Why so few fluid phases?

Taking a look at the phase diagram of water By Cmglee - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=14939155 I see ice phases as much as up to 'Ice XI', but only one ...
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2answers
57 views

Henry's law Numerical

I got very basic doubt. Henry law's Give relation between concentration vs Partial pressure. So here is the Numerical Of my textbook **Now My question is, why concentration is Considered only in ...
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1answer
40 views

why is avagadro's statement true that at STP conditions all matter have same number of atoms or molecules?

As atomic number increases, atomic size, number of electrons and shells also increase. So due to higher atomic size and maximum number of electrons, there should be maximum repulsion forces between ...
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14 views

How to calculate the osmotic pressure of a solution that has two different solutes dissolved in it?

How do I calculate osmotic pressure of a solution that has two different solutes (pectin and sucrose) dissolved in it? The conditions are like this: $1.5\%$ of $\rm100,000~\frac{g}{mol}$ pectin ...
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16 views

structure of an electrochemical cell

in an electric circuit voltmeter is installed parallel , since it has a very big resistance and in the ideal form it s resistance is + infinite, but in chemistry, in electric cells, we install ...
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36 views

Can we make glass by heating Martian Soil

I was puzzled by a very interesting question. Can we heat up Martian sand and produce glass just the way we do here on Earth. (The Basic way) For info, Martian sand consists of the following - ...
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2answers
21 views

Enthalpy and Internal Energy in Constant Volume Calorimeter

It is my understanding that enthalpy differs from internal energy only in that the change in enthalpy takes into account any pressure-volume work done on the system (or by the system) in a reaction, ...
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What is the difference between standard chemical potential (μ standard) and the “pure” chemical potential (μ*)?

I am studying solutions for my thermodynamics course and I am a little confused about the chemical potential of a solute. I found the following from Atkins: For a solute $\ce B$,obeying Henry's ...
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17 views

Can you get oxygen form silica or alumina?

If I had a lot of silica or alumina, like on the moon, would I be able to split the silica or alumina into aluminium and oxygen/ silicon and oxygen? It doesn't matter how unpractical it is. If there ...
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28 views

Solution not passing through filter paper

Is there any reason why a mixture of 2 immiscible solutions, when filtered, separate so that one passes through the filter paper and the other doesn't? I thought that only solids won't pass through ...
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2answers
37 views

How do we find the angular, radial nodes and the quantum numbers when the radial probability distribution curve's equation is given?

I am having serious conceptual issues with the schrodinger equations. Please note that I only have basic school level(11th grade) knowledge of this thing and we are expected to know very little about ...