We’re rewarding the question askers & reputations are being recalculated! Read more.

Questions tagged [physical-chemistry]

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

Filter by
Sorted by
Tagged with
0
votes
0answers
9 views

How is molefraction of a solution different in vapour state vs in solution vs vapour-liquid equilibrium?

I have this question we are given 'x' grams of benzene and 'y' grams of toulene, it is said that the vapour pressure of benzene is 75mmHG and that of toulene is 22mmHG and we are supposed to find mole ...
0
votes
0answers
15 views

Find m of Na2S04? [on hold]

Can someone help me on this problem. A solution is prepared at 25 °C by mixing 25 g of Na2S04 with 150 cc of water. The density of water at this temperature is 1 g/cc/. What is the m of Na2SO4 in the ...
0
votes
0answers
10 views

Find solute of Molecular Weight [on hold]

Can someone help me on this question. A 0.76 g of an unknown solute, X, is dissolved in 18.5 g of hexane and the solution is found to be 0.25m. What is the MW of solute X?
-1
votes
0answers
16 views

Can an electron of a atom of restricted to 2nd shell be excited to third shell?

If there is an electron in the 2nd shell in the s subshell, can it get excited to the 3rd shell or is it only limited to the p subshell? Like hydrogen has only the 1st shell but I've seen many ...
1
vote
1answer
33 views

What is the relationship between enthalpy of atomisation and enthalpy of sublimation?

We know that we have to first break the metallic lattice to turn the metal into a gas and hence there should be some sort of relation between the two. I am trying to answer this question: The $E^θ(...
0
votes
0answers
19 views

What is the formula for vapor pressure of liquid related to surface tension of liquid?

What is the formula for vapor pressure of liquid related to surface tension of liquid? I know that if the surface tension increases, vapor pressure will decrease. Toluene evaporates faster than ...
0
votes
2answers
77 views

How can I find the Van der Waals constants (a and b) without any critical values?

I'm given a container of gas that is kept at constant temperature, and whose volume is decreased by applying pressure, from A to E, as the graph shows. I am given the temperature, the total moles in ...
-2
votes
0answers
22 views

Can a system be designed which equates reaction rates of endothermic reactions using a single power source? [on hold]

My goal is to use a single source of heat in an experiment with 2 separate endothermic reactions. My hypothesis is that by conducting this experiment under water, the reaction time of both of the ...
-1
votes
1answer
41 views

Why is the rate of effusion of a gas inversely proportional to (absolute) temperature? [duplicate]

(iv) Rate of effusion of a gas: The rate of passing of a gas through an orifice may be given as: $$r = \frac{PA}{\sqrt{2\pi RTm}}$$ where $P = $ Partial pressure of the gas $A = $ Area ...
-3
votes
1answer
46 views

Calculating pressure [on hold]

Calculate the pressure in Pa of a 760mm column of mercury when the density of Hg is 13.5951g/cm^3 at room temperature. P= dgh P=(0.0135951kg/cm^3)(9.81m/s^2)(0.76m) P=0.101 Where did I go wrong? ...
-1
votes
0answers
28 views

Need a container filled with gas phase anions (negatively charged gas molecules/particles) for an experiment [on hold]

Does this even exist? How could I get it? Could I make it? I know that most gas molecules/particles have an overall neutral charge. But I need gas phase molecules with an overall negative charge (i.e ...
-1
votes
1answer
82 views

What happens when Ar and HCl are mixed at 77 K? [on hold]

So our teacher asked us a simple question in the classroom: What happens when Ar and HCl are mixed at 77 K? and no other information was given. We replied various possible answers for that such ...
7
votes
3answers
2k views

Why does radiocarbon dating only work in nonliving creatures? [duplicate]

I understand how carbon dating works, though I do not understand why it doesn't happen while a creature is living. Because while we are alive we still have carbon 14 in us, so shouldn't it work?
-2
votes
0answers
26 views

Mixture Question [on hold]

The extent of ionization of NaCl and MgCl2 in water is 80% and 50% respectively. If a sample of water has 5.85% (w/w) NaCl and 9.5% (w/w) of MgCl2, ( Kb = 0.52Kkg/mol) Does the mixture acts as an ...
-3
votes
0answers
19 views

Application of general binding equation in ITC experiment [on hold]

A hypothetical protein $(\ce{M})$ binds a ligand $(\ce{X})$ with $1:1$ stoichiometry, a dissociation constant, $K_\mathrm{D} = \pu{1 μM},$ and binding enthalpy $ΔH = \pu{-5 kcal/mol}.$ Suppose an ITC ...
-2
votes
0answers
17 views

Order of reaction in adsorption process

(1) $\ce{PH3(g) <=>[W]PH3(adsorption)->[W]P(s) + 3/2 H2(g)}$ The decomposition of phosphine on tungsten surface at low pressure is a pseudo first order reaction. This is because the rate of ...
-3
votes
0answers
38 views

KineticTheoryofGasesquestion [on hold]

More than one correct: The isothermal compressibility is a function defined by Z = -(1/V)(dV/dP). a)Z for ideal gas > Z for real gas when T > a/(bR) b)Z for ideal gas < Z for real gas when T > a/(...
-1
votes
0answers
34 views

Is it possible for the vapour pressure to exceed the boiling point? [on hold]

An unknown molecule has a normal boiling point of $\pu{339.15 K}$ and a vapour pressure of $\pu{2 atm}$ at $\pu{329 K}.$ Determine the pressure, in mmHg, at which this unknown liquid will boil at $\...
1
vote
0answers
15 views

Interpretting relative probabilities based on Boltzmann's probability distribution?

I understand that Boltzmann's probability distribution gives the relative probability of one microscopic state in comparison to the other (P1/P2) but I don't know how exactly to understand this. For ...
2
votes
1answer
70 views

How to calculate the number of protons in a sphere given the volume and the pH?

The spherical radius of a nano-droplet of a solution ($\mathrm{pH}$ of which is $6$) is given as $\pu{20nm}$. I can find the molar concentration of $\ce{H+}$ and subsequently the number of $\ce{H+}$ ...
-1
votes
1answer
18 views

Chemical equilibrium [duplicate]

When calculating equilibrium constant with partial pressures if there is a solid involved should we consider it in the total number of moles in mole fraction?
-1
votes
0answers
12 views

Heat Capacity and Joules [on hold]

I am unsure of how to work out the heat to energy ratio that the problem depends upon. When I look at the first part I see that it is asking me to calculate energy use using the previously given ...
3
votes
2answers
59 views

Giving too much energy to an exothermic reaction [on hold]

What will happen in an exothermic reaction if more than required energy is given? I mean, will it produce even more energy which will be highly dangerous or nothing will happen according to Le ...
1
vote
1answer
37 views

What is a material more easily cut than shattered? [on hold]

I'm currently developing a sci-fi concept for animation which partially involves a typical "the earth has been overrun by XYZ" scenario. One of the ideas for XYZ we're thinking of is a species of ...
0
votes
0answers
43 views

Validity of Maxwell-Boltzmann distribution for solids [duplicate]

Suppose there is a solid made of avogadro number of, say, aluminium atoms. This solid is kept at 273 K. According to Maxwell-Boltzmann distribution, all the particles or atoms will not have the same ...
0
votes
0answers
28 views

Efficiency of liquid–liquid extraction [closed]

I was wondering what could be the main reason that determines the efficiency of separation in a liquid–liquid extraction (LLE) process. I can only think of solvent selection such as the solubility of ...
-1
votes
0answers
16 views

Gain of electron by metals [closed]

Under what condition or situation does metal gain an electron? what kind of bond does it form in such a situation?
-4
votes
0answers
17 views

calculate the enthalpy of solution for ammonnium chloride [closed]

What is the change in temperature when 3.00 grams of ammonium chloride is dissolved in 100 mL of water? change is temp was -1.99 Given the change in the temperature from adding 3.00 grams of ...
0
votes
1answer
36 views

Order of reaction for hydrogen ions being ignored

I have been reading through a case study about calculating the order of reaction for the following reaction: $$\ce{H2O2 + 3 I- + 2 H+ -> I3- + 2 H2O}$$ The paper uses an iodine clock reaction ...
-1
votes
0answers
23 views

Identifying Isotopes [closed]

If the silicon has 3 naturally occurring isotopes Si-28, Si-29, Si-30. Which isotope is most abundant in the world and explain how you know.
1
vote
1answer
96 views

Reaction with tin(IV) iodide and hydrogen peroxide [closed]

Today I reacted tin(IV) iodide $\ce{SnI4}$ (dissolved in water) with hydrogen peroxide. This produced a yellow/brown colour (I'm guessing due to formation of $\ce{I2}?).$ I then added some petroleum ...
0
votes
1answer
19 views

What exactly causes equilibrium to shift when pressure is decreased? [duplicate]

Take the reaction: $$\ce{N2(g) + 3 H2(g) <=> 2 NH3(g)}$$ If pressure is decreased, equilibrium shifts to the left because it has more moles. I understand the basics of why this is, i.e. due to ...
2
votes
2answers
81 views

Why when deriving the Clapeyron equation can you assume that dH = dq, as surely the pressure is not constant?

Part of the Clapeyron equation involves replacing $\Delta S$ with $\Delta H/T$. I can see the step from $\Delta S$ to $\Delta q/T$ but I'm not sure why you can replace $\Delta q$ with $\Delta H$. From ...
4
votes
1answer
64 views

What is the electrochemical reaction of this battery?

I've watched a YouTube video "Soda Can Battery - Power From Trash - DIY Project" by Source Port Services. I understand that the anode can be oxidised, but what is the reduction reaction at the cathode?...
1
vote
1answer
40 views

Feasibility of using ionic liquid fuels in an MHD type reactor

First off I would like to say that my knowledge on chemistry, even general chemistry, is basic if not poor. That said, I have some intuituions on this matter. I haven´t found any paper regarding ...
1
vote
1answer
34 views

Under what circumstances that Liquid-Liquid extraction would be good to use? [closed]

Under what circumstances that LLE would be useful ? Are the 2 top reasons - 1. Difference between the boiling points of the components are very low or similar. 2. For Temperature sensitive compounds ...
0
votes
1answer
51 views

Finding change in activation energy from change in rate constant in catalysis

I need to find by how much the activation energy decreases when the rate constant increases by a '$x$' factor when a catalyst is used in the reaction. I'm just super confused about how to solve this....
3
votes
0answers
127 views

Ground state term symbol, why is $L = |M_L|$, if L must be a maximum?

I'm trying to understand how to predict ground state term symbol of atoms. After finding the biggest S, why the biggest L will be $L = |M_L|$, where $M_L = \sum m_l$? I know this rule works to ...
0
votes
0answers
35 views

Energy of mercury(II) oxide decomposition

Study check 9.11 from [1, p. 298]: Mercury(II) oxide decomposes to mercury and oxygen. $$\ce{2 HgO -> 2Hg + O2}\quad ΔH = \pu{+182 kJ}$$ […] b. How many kilojoules are needed when ...
1
vote
1answer
43 views

Energy required for obtaining required mass of aluminium from alumina via electrolysis

How do I know how much energy I need to obtain 20 g alumunium from alumina with 5 V? I calculated the quantity of electricity is 2.22 F. Any help appreciated!
1
vote
1answer
30 views

Internal energy change for reactions at constant volume vs constant pressure

The reaction of cyanamide, $\ce{NH2CN(s)},$ with dioxygen was carried out in a bomb calorimeter, and $∆U$ was found to be $\pu{–742.7 kJ mol-1}$ at $\pu{298 K}.$ Calculate enthalpy change for the ...
-2
votes
0answers
24 views

Equilibrium Constants [duplicate]

I'm failing to understand Spectroscopic Determinations for equilibrium constants. Would someone be able to elucidate for me? I know we have to use Beer's law, but I can't seem to wrap my mind around ...
0
votes
0answers
15 views

Could I make a lava lamp using diluted oil paint for the blobby part?

So, on a whim I decided to try making a lava lamp for my roommate. I know that lava lamps are made with dyed water/salt water and a trade secret mix of paraffin/wax/dye/heavy solvent that is just ...
2
votes
3answers
157 views

melting and boiling …really equilibrium? [closed]

Why are melting and boiling considered equilibrium processes even though the amount (concentration) of both phases keep changing i.e from solid to liquid and so on?
1
vote
0answers
46 views

Is it possible to create an arbitrary, stable, unique chemical fingerprint? [closed]

Context: I want to be able to hash real-world objects Is it possible to create a substance containing a combination of elements (or isotopes?) in a random and difficult to reproduce (but simple to ...
-1
votes
0answers
14 views

Synthesis of AgI/rgo

Synthesis of AgI/reduced graphine oxide using 80 mg of AgI and 1.25 wt % of RGO. This means we are adding 100mg of RGO(solute) to 80mg of AgI right?
1
vote
1answer
45 views

Decomposition of total Interaction energy with SAPT or EDA-NOCV

I want to perform energy decomposition analysis for some Hydrogen bonded complexes. I came to know that ORCA and Psi4 allows EDA-NOCV an SAPT(0,2,3) respectively. But I do not know which one would be ...
1
vote
0answers
32 views

During solid-solid phase transition, if both solid phases are incompressible, is ΔG independent of p?

Source: Atkins Physical Chemistry, Ninth Edition, page 154, Problem 4.13: Show that, for a transition between two incompressible solid phases, ΔG is independent of the pressure. My attempt: ...
1
vote
0answers
19 views

Carbon Capture Absorption with Henry's Law

Assume the Henry’s coefficient for water at $\pu{20 °C}$ is $\pu{1.6E8 Pa}.$ What is the mole fraction of $\ce{CO2}$ that will be dissolved in water assuming that it is at equilibrium with a flue gas ...
1
vote
1answer
39 views

Intuition for the overlap integral

I want to ask a question about the overlap integral. I was studying about the MO diagram of $\ce{H_2^+}$ and we managed to derive an expression which had the following term: $$\langle \mathrm{1s}_\...