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Questions tagged [phase]

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.

2
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1answer
48 views

Freezing trend of water

In this experiment, I used a digital temperature probe to measure the freezing point of water and some other salt solutions. I was just wondering if there was any explanations for 1. The first ...
12
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2answers
4k views

Why does ice crack when a drink is poured on it?

I think most people have experienced this, but while pouring a beverage over ice I noticed the ice cracked. Before After My initial thought was that because the beverage has an antifreeze property ...
0
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0answers
54 views

Freezing point depression of salt solutions

I have recently come across this particular equation which is used to estimate the freezing point depression of a salt solution: $$\theta_\mathrm{B} = \frac{\Delta H^\mathrm{fus}_{0,T_\mathrm{F}} - ...
28
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4answers
1k views

How many molecules does it take to have a phase?

A single molecule can't be solid, liquid or gas. It's just a molecule. A mole of something can be any of the three. So, how many molecules does it take for phases to be meaningful? I realize that ...
5
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1answer
253 views

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

I would like to simulate phase separation in LAMMPS and need advice what kind of two particle systems and interactions will yield phase separation. For example, a meta stable phase separation is ...
0
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1answer
29 views

Impact of Pressure on equilibrium of Tin allotropes

The pressure at the bottom of the Mariana Trench in the Pacific Ocean is $1090$ bar. What temperature will the two allotropes of tin be at equilibrium? Assume that the molar volume, energy, and ...
4
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1answer
26 views

Phase abbreviations for non-aqueous solutions

When writing a chemical equation, how do you indicate that a chemical is dissolved in a non-aqueous solvent? For example, it would be inappropriate to write X (aq) when X is dissolved in benzene, ...
-1
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1answer
35 views

Water vapour pressure in oxygen gas bubble

Suppose we have a source of O$_2$ bubble formation in water at specific nucleation sites, how can we estimate the water vapour pressure inside the O$_2$ bubbles? I know that: (1): $p_\mathrm{O_2}+...
3
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1answer
136 views

Clausius–Clapeyron relation for states of water and vapor

I've seen many questions about this topic on this site, but I still have some issues trying to understand this aspect. Here's what I believe I understood looking at the phase diagram for a pure ...
1
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1answer
4k views

Calculating the mass of water removed by air conditioning condensation

I cannot figure out how to calculate the mass. The question is: "Suppose the percent relative humidity is $\mathrm{80.0\%}$ at $\mathrm{91.4\ ^\circ F}$ ($\mathrm{33.0\ ^\circ C}$) in a house ...
1
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2answers
30 views

How does the process of nucleation work for boiling liquids?

I have a somewhat clear picture how (on the molecular level) a gas turns into a liquids as it cools. When a gas has a certain temperature, its molecules on average have a high enough kinetic energy so ...
1
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0answers
16 views

Explanation of phase changing/solid and liquid water existing in the same container at same temp [closed]

I was trying to explain to a friend the other day why when ice and water are in the same container, the water is 32 degrees Fahrenheit or 0 celcius, but not frozen, because the ambient temp is above ...
2
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1answer
160 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 ...
3
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1answer
44 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 ...
2
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2answers
106 views

Does hydrazine crystallize when freezing?

When discussing problems of keeping hydrazine from freezing on spacecraft we stumbled upon a question: can pure hydrazine separate through fraction-freezing from the stabilizing substances like UDMH? ...
5
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3answers
4k views

Why is ice less dense than water?

I know the traditional explanation, which says that ice has large spaces between $\ce{H2O}$ molecules because hydrogen-bonding gives it an open structure. But what does the open structure have to do ...
-1
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1answer
30 views

How does the theory of thermodynamics account for warm water freezing before cool water?

According to typical sources on thermodynamics, the warmer a liquid is, the longer it will take to freeze it. For example, I recently was reading a book on refrigeration and this book specifically ...
1
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2answers
32 views

Is there a metal for which its gas is necessarily a plasma?

Related to this question: Gaseous metals? The top answer clarifies that even with metals, the gaseous state is distinct from a plasma. However, my question is, is this actually true in all cases? Or ...
4
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1answer
839 views

Structure of a metal in gas phase

If we have a metal in gas phase. Suppose lets say aluminium. aluminium has delocalised electrons. There is Al cation -electron attraction in it. Its easier to visualize Al atomic structure in solid ...
0
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1answer
68 views

Depression of freezing point [closed]

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 ...
13
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4answers
717 views

Room-conditions supercritical fluids?

Are there any reasonably obtainable supercritical fluids that I could, say, run my hand through? Wikipedia makes it sound like there are plenty of room-temperature ones, but no room-pressure fluids.
4
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1answer
3k views

What defines matter's phase at room temperature?

So, a simple question: what makes neon a gas; what makes water liquid; what makes plutonium-238 a solid at room temperature? Of course, the phase is determined by the excitation of the molecules, but ...
4
votes
1answer
154 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 ...
2
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1answer
52 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 ...
1
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2answers
797 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. ...
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5answers
4k 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 ...
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0answers
97 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 ...
2
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1answer
5k views

Freezing of vinegar

Concentrated acetic acid freezes around seventeen degree Celsius. Water freezes at zero degree Celsius. But Vinegar has a very low freezing point , that is around minus two degree celcius. Why is it ...
2
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0answers
82 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 ...
10
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3answers
26k views

Why does small value of van der Waals gas constant “b” ensure easier liquefication?

Larger value of b signifies that the size of the molecules is larger and hence the forces acting should become larger due to increased surface area.This should ensure easier liquefication. But my book ...
5
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1answer
2k views

Why does water become less dense when it cools

Most materials become more dense as they cool, but ice floats in water, meaning that it's less dense. Why is this?
5
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2answers
2k views

Having trouble understanding the iron-carbon phase diagram

At room temperature, alpha and alpha+$\ce{Fe3C}$ are present (depending on carbon content), which is ferrite and pearlite. In the lab we polished and etched samples of carbon steel to observe the ...
36
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6answers
394k views

Why does ice water get colder when salt is added?

It is well known that when you add salt to ice, the ice not only melts but will actually get colder. From chemistry books, I've learned that salt will lower the freezing point of water. But I’m a ...
4
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3answers
817 views

Proof of Dynamic Nature of Equilibrium

Here is how my textbook proves that dissolution of solid in liquid is dynamic in nature. It considers the example of a saturated solution of sugar. It says that, Though the solution is in ...
0
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1answer
31 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) ...
1
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4answers
1k views

Liquification of gas to liquid at critical temperature

The gas that liquifies first, when cooled from 500 K to its critical temperature given in parenthesis is a) $\ce{CO2}$ (304.1 K) b) $\ce{NH3}$ (405.5 K) c) $\ce{O2}$ (154.3 K) d) $\...
0
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2answers
59 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 ...
0
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0answers
85 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 ...
7
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1answer
5k views

Why does color of halogen deepens and the boiling point decreases down the group?

Why does the color of the halogens deepens as we go down the group? also why there is a change in physical state of halogens down the group? \begin{array}{c|c} \mathbf{Gas} & \mathbf{Color} \\\...
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0answers
35 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 ...
4
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1answer
68 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{...
0
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1answer
57 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
426 views

Why does the freezing point of a sample gas occur at a certain temperature? [closed]

From "North Carolina Measures of Student Learning: NC’s Common Exams Chemistry" (Source, Number 20): The graph below shows a cooling curve for a sample of gas that is uniformly cooled from $155~^\...
1
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1answer
29 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(...
0
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0answers
31 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
119 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 ...
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1answer
61k views

What is the melting point of diamond?

Textbooks and the online reference differ about this and there are more than two answers.
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2answers
118 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 ...
5
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2answers
1k views

Why does sodium polyacrylate solidify, on addition of water?

Sodium polyacrylate is a white powder with a characteristic odor. But when we add water to this powder, instead of forming an aqueous solution, it instantaneously solidifies and forms more amount of ...
2
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1answer
74 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 ...