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An entity of a material system which is uniform in chemical composition and physical state. This tag should be applied to question regarding chemical and physical properties of phases, systems of phases and also phase transition processes.

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1answer
22 views

Depression of freezing point [on hold]

Recently, I learnt that by adding a non-volatile solute to a solvent, the vapour pressure of the solution is decreased and consequently its boiling point. Also consider the definition of the ...
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0answers
26 views

Using lever rule [duplicate]

How do I find fraction of phases at $800^{\circ}$ (using lever rule)? In an alloy with two phases, α and β, which themselves contain two elements, A and B, the lever rule states that the weight ...
2
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1answer
48 views

What is the topology of a phase diagram?

This question is cross-posted from phys Looking at various two-variable phase diagrams I was struck by that on every one I have seen so far all the phases formed simple connected regions; see, for ...
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0answers
30 views

How much urea will separate out?

I have a question of solution chapter and I m having problem in both in solving as well as understanding that problem . The problem is: "One hundred grams of a $\pu{5m}$ urea solution is cooled to $...
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0answers
25 views

Why are Txy diagrams curved for dew point and bubble point?

What is the reason behind drawing dew point curve and bubble point curve as curved (and dew point curved outwards and bubble point curved inwards) for Temperature vs Composition Phase Diagram as per ...
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0answers
34 views

Freezing water droplets with liquid nitrogen vapor

I have an idea for a device but I'm not sure about the thermodynamics. Would liquid nitrogen vapor (not liquid) be cold enough to instantly freeze a spray or mist of water? I know water freezes at 0 °...
2
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0answers
47 views

How to without calculations understand the liquid-liquid extraction efficiency?

I'm asking myself this question for a very long time and I haven't found a simple an good explanation yet for the fact that it's better (if you want to clean them) to wash your hands two times with ...
3
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1answer
33 views

carbon dioxide in liquid and gaseous phase with liquid water

What are the differences between carbon dioxide solubility (miscibility, reaction) in liquid water when in gaseous ($\pu{<38 bar}$) and liquid ($>\pu{38 bar}$) phase? The temperature in my ...
0
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1answer
26 views

Will a container made of ice hold an alcoholic beverage that is below freezing in an environment that is also below freezing? [closed]

This very specific question that came after saw I a travel episode where they served alcoholic beverages in ice glasses in an ice bar. I wondered if the drink contents would stay in the glass (of ice) ...
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2answers
57 views

Why do we use the word phase and state of matter so interchangeably? [closed]

I would be happy if someone explains me why the word "phase" and "state of matter" is used so interchangeably.Lets say we have HBr and another compound in the system both gases.Then am I to take two ...
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0answers
38 views

How to calculate the enthalpy of fusion at a different temperature?

The heat capacity of liquid iodine is $80.7$ $\ce{J*K^{-1}*mol^{-1}}$, and its enthalpy of vaporization is $41.96$ kJ $\ce{*mol^{-1}}$ at its boiling point ($184.3$ $\ce{^oC}$). Furthermore, the ...
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0answers
32 views

Which phase offers resistance when oxygen is being absorbed in strong alkaline pyrogallate solution?

While solving a few questions from interphase mass transfer I came across this question. The question stated that when oxygen is being absorbed from air to water it is a liquid phase resistance ...
0
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1answer
53 views

Relative magnitudes of intermolecular forces from phase diagrams

Is it possible to say whether or not a system A or B has stronger intermolecular forces from a phase diagram according to which: The $T_{\text{b}}$ of A is lower than the $T_{\text{b}}$ of B. The $T_{...
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1answer
28 views

Reaction direction change based on phase of reactants and products

I am curious specifically how the entropy of a reaction will change if the phases of the reactants and products at different conditions change. For instance, a reaction $$\ce{O2(g) + C(s) -> CO2(...
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0answers
22 views

How many components and phases are in an equilibrium system comprising lead sulfate, lead ions, and sulfate ions?

I am going to calculate the degrees of freedom ($F = C-P+2$) on the following system, but I can't figure out whether we have to take $\ce{PbSO4}$, $\ce{Pb^2+}$ and $\ce{SO4^2-}$ as a single component ...
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2answers
84 views

Why are temperature and pressure represented as the number 2 in Gibbs' Phase Rule?

In our class we are learning about Gibbs' Phase Rule; $F=C-P+2$, in which $F$ stands for degree of freedom, $C$ for number of components, and $P$ for number of phases in the system. Our professor told ...
4
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1answer
102 views

Which invariant reactions are congruent?

I am studying the concept of incongruent melting and invariant reactions. I was wondering, would all the invariant reactions that I show below be incongruent? As I understand it, we can only have ...
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2answers
86 views

Formation of strontium peroxide

Wikipedia states: Strontium peroxide is produced by passing oxygen over heated strontium oxide. Upon heating in the absence of $\ce{O2}$, it degrades to $\ce{SrO}$ and $\ce{O2}$. I found some ...
2
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1answer
71 views

How long does a wine sauce need to simmer for to reduce the alcohol to less than one percent [closed]

Perhaps you can shed some light on this topic for me. I've recently researched the topic of boiling off alcohol while cooking--specifically how long one needs to simmer alcohol to boil it off. I'd ...
1
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0answers
41 views

What's the density of a frozen ethanol or ethanol solutions?

How can we know what's the density of ice (water), but there's no data on how much is the density of frozen ethanol? (as far as I know)
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1answer
77 views

Why hot water freezes faster than cold water? [closed]

When we put cold water in the fridge it takes time to freeze but hot water is fast in freezing.Why?
-1
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1answer
133 views

What is the difference between air and evaporated water (steam)?

I was thinking about the difference between air and water, and how water evaporates as steam and becomes air. This led me to believe that air is just evaporated water. However when I read about air it ...
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0answers
35 views

How to determine the phases in a complex phase diagram?

In my school notes, we have the following phase diagram that shows an example of how complex things can get when we have intermediate phases. I tried filling in phases, but I have no idea how to check ...
4
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0answers
41 views

Form ice from water in a non-deformable, completely sealed box [duplicate]

Suppose that I put some water in a non-deformable, completely sealed box, in a way that all the space is occupied by water, and reduce the temperature to transform water to ice. Since ice takes more ...
8
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5answers
3k views

Why does the distance between molecules increase when the temperature is raised?

I have learnt that when we heat ice-like substances it changes to water and when I asked my teacher she said that the distance between molecules increases. When I thought about it a bit more a ...
2
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1answer
52 views

What are some examples of pure substances with no liquid state? [closed]

For example, A molecular substance that decomposes before melting, and under pressure can only assume a liquid state that doesn't contain the same molecules, for example a mixture of the elements of ...
1
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1answer
58 views

How do phase transitions occur in the solid phase? [closed]

For example, how does graphite transform into diamond as pressure increases at a certain (adequate) temperature? I'm not sure if this is a great example to look at the bigger picture, so another ...
5
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1answer
162 views
+50

How to simulate phase separation in a discrete system using LAMMPS?

I would like to simulate phase separation in LAMMPS. I am looking for advice what kind of 2 atom system and interaction will experience a phase separation. A continuous phase flow model governed by ...
0
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0answers
63 views

What causes both components of a binary gas mix to condensate at the same time for a given composition

Okay, so recently I encountered the temperature - mole fraction diagrams for binary vapour-liquid equilibrium. For now, I only consider two-component systems where the components are very similar and ...
1
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1answer
145 views

Material that changes color when changing phase from solid to liquid [closed]

I was asked and am wondering myself, what are materials that change color when molten? I could not find any examples online, but it really interests me. I would to get some examples which have one ...
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1answer
38 views

What is the definition of a component in a phase diagram?

I have been trying to understand the concept of a component in relation to phase diagrams in my materials class. I have tried searching online and found that the definition is supposed to be that a ...
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0answers
196 views

Freezing of alcohol water mixtures below the triple point pressure of water

What happens when you try to lower the pressure of an alcohol-water mixture below the triple point of water? To give a specific example, the freezing temperature of a 50-50 (by mass) ethanol-water ...
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0answers
26 views

Why do frozen whipped cream remain “frozen” when thawed?

I froze some pastry with whipped cream on the other day (by mistake, I placed it on my balcony and expected it to be a few degrees above zero, but it wasn't). When I unfroze it again I was expecting ...
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2answers
492 views

What are the degrees of freedom (from Gibbs phase rule) for an azeotropic mixture?

For an azeotropic binary mixture, the number of phases is 2 and number of components are 2. So, according to Gibbs phase rule, the number of degrees of freedom should be 2. But, the right answer is 1. ...
3
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1answer
154 views

What changes does zinc chloride undergo when ‘fusing’ on an atomic level? How does this influence reactivity?

I have been using a reaction with an organozincate starting material. This zincate is freshly prepared from zinc chloride and a Grignard reagent. The experimental procedure ‘handed down’ from more ...
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1answer
44 views

How do they come up with a freezing point of ~-60F for CaCl2 & H20?

What am I missing? I cannot reconcile the difference between what the internet says the freezing point of CaCl2 is vs the calculation, which means my calculation must be off, but I am not sure how. ...
4
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2answers
124 views

Ice Crystal Matrix measurements of H2O molecules?

I want a mathematically generated 3D STL copy of this image, however it's represent algorithmically. If I do all the H2O's as individual pieces with female connections prepared for chopped bike ...
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0answers
82 views

Can every liquid pure substance be compressed to solid?

Apart form the fact that liquid are often misleadingly considered incompressible, fact that I recently find out to be true only as an approximation in specific circumstances. I was curious to know if ...
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2answers
479 views

If melting points and freezing points are the same, what state is pure equilibrium?

If melting points and freezing points are the same, what state is pure equilibrium? I understand melting points and freezing points are the same; adding or removing temperature of melting points for ...
3
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2answers
52 views

Effect of doubling kinetic energy on phase transitions

The kinetic energy of the molecules in a sample of $\ce{H2O}$ in its stable state at $ \pu{–10 ˚C}$ and $\pu{1 atm}$ is doubled. What are the initial and final phases? [US National Chemistry ...
4
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1answer
65 views

Colloids and Ions

Suppose I have this reaction: $$\ce{3NaOH(aq) + FeCl3(aq) → 3NaCl(aq) + Fe(OH)3}$$ My questions: $\ce{Fe(OH)3}$ doesn't have the (aq) suffix because it isn't separated in water as opposed to $\ce{...
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0answers
83 views

Why does CO2 only exist in gaseous and solid state under STP/SATP?

Why does carbon dioxide only exist in gas and solid state under STP/SATP conditions? $\ce{CO2}$ pressurized to $\pu{5.1 atm}$ can exist in all 3 states: solid, gas, and liquid. However, why couldn't ...
2
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1answer
143 views

Interpreting from phase diagram whether O2 will float or sink

The normal melting and boiling points of $\ce{O2}$ are $\pu{-218 ^\circ C}$ and $\pu{-183 ^\circ C}$, respectively. Its triple point is at $\pu{-219 ^\circ C}$ and $\pu{1.14 Torr}$, and it's critical ...
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1answer
67 views

Can I supercool and solidify a liquid multiple times?

Let's say that I supercool a bottle of beer and then tap it so it freezes and solidifies. If I were to allow the frozen beer to melt completely, and then freeze the same bottle again, would it still ...
3
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1answer
37 views

Is supercriticality dependent on partial presssure, or total pressure?

Supercritical CO2 is commonly used as a solvent in organic chemistry (notably in industrial processes like decaffeination). I presume that in such cases, the CO2 is typically pure, or very close to it....
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2answers
204 views

Water cooling by evaporation

For many years of drinking water has been cooled in hot climates by evaporating it from the surfaces of canvas bags or porous clay pots. How many grams of water can be cooled from $\pu{35 ^\circ C}$ ...
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1answer
108 views

Lever rule confusion

At point a3, I know the ratio of the liquid phase to the solid phase, but I don't get the highlighted statement which says b3 gives the composition. I thought a3 already gave the composition? Do I ...
2
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1answer
125 views

Given this liquid-liquid phase diagram, is the green line the nitrobenzene-rich phase?

The temperature-composition diagram for hexane and nitrobenzene at 1atm. The region below the curve corresponds to the compositions and temperatures at which the liquids form two phases. The upper ...
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3answers
535 views

If hydrogen bonds are chemical bonds, and these bonds are broken when water changes phases, why doesn't this classify as a “chemical” change?

This is more of a terminology question. How are phase changes considered a physical property, not a chemical property when hydrogen bonds break. A chemical property can only be observed during a ...
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0answers
167 views

Why droplets of water and ethyl alcohol solution freeze weirdly? [closed]

I'm doing a project where I freeze water drops and solutions with water and ethyl alcohol. It's a phenomena where drops create a conical shape at the end of their freezing. But with ethyl drops, with ...