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.

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Energy absorbed by a system in isothermic process in which the phase changes from liquid to gas

A system contains $x$ mole of material, with surface area $S$ is pressed by a mass $M_1$ (no fraction and no any other outer forces involves). Let $\Delta H_\mathrm{l\rightarrow g}$ be the transition ...
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Why does ordinary water have a triple point?

Triple points and triple lines for pure substances and mixtures My understanding is that pure substances can have triple points. But mixtures of substances have triple lines, i.e. there isn't a ...
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Freezing point of solution

It's stated in my textbook that at the freezing point, the vapour pressure of the solid phase equals the vapour pressure of the liquid phase. In a mixture, since the vapour pressure of the solution is ...
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1answer
58 views

Boiling point of liquids [closed]

If we can have liquid - vapour equilibrium at any temperature what is the 'point' behind boiling point.Boiling point is just a special case of liquid - vapour equilibrium where partial pressure equals ...
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Determine direction of mass transfer

For part a) I don't really know what to look at. Diffusion occurs from low to high concentrations so by looking at $t_1$ I would say that the direction of the mass transfer is from phase II (organic ...
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Can we estimate if a substance will be in gas state at certain temperature?

Sometimes, by ballparking, we can estimate that a certain substance isn't in the gaseous state at room temperature because it has a large molecular weight. There is a direct relation between ...
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Predicting pressure inside a container based on temperature

I'm a mathematician and computer scientist, and for this particular problem I would benefit from some chemical expertise. Suppose I fill a container up with some liquid propane. I believe this is ...
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Which “exotic salt” can lower water's freezing point by 70 °C?

The Medium.com article Mars Phoenix Lander, 10 Years Later shows several remarkable images and discoveries on Mars by the Mars Phoenix Lander circa 2008. One image (shown below) shows what looks like ...
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When it rains, it puddles. Spilled salt cycles between wet and dry with humidity. Is this akin to a phase change?

I have some spilled un-iodized table salt (NaCl). It is very humid where I live, and when it gets very humid for a few days, the salt absorbs so much water that it becomes a puddle of (probably) ...
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How to calculate dew point of air-water system

I want to calculate the maximum water holding capacity of air at a given temperature (as in $\frac{max\ mass\ of\ water}{mass\ of\ dry\ air} $ vs temperature) I looked up online and there are ...
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What happens when para-water ice is suddenly melted?

Background (hydrogen) In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic ...
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Use a solid or liquid stationary phase in gas chromatography

In my textbook, they mention that the stationary phase used in gas chromatography is a solid, such as silica or an adsorbed high-boiling-point liquid. My question is that what is the advantage of ...
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Can amorphous polymers have a melting temperature as well as their glass transition transition temperature?

Above the Tg, amorphous polymers are described as viscous liquids. What then would they be likened to above their melting point, should they have one?
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Will evaporation from two immiscible liquids blow up a balloon?

Consider the following setup: Two immiscible liquids A and B are placed inside a balloon at a temperature where neither one of them boils. The inside of the balloon contains some argon, and the ...
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Is it possible to boil a liquid by just mixing many immiscible liquids together?

In open air, when vapour pressure reaches 1 atm, boiling takes place. I read that if we add two immiscible liquids together, the total vapour pressure of the 'mixture' is close to $p = p^*_A + p^*_b$,...
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Eutectic Phase Diagram of Al-Si Analysis

Hello, How can I know from this phase diagram: 1. The composition of the alloy Al-Si that allows precipitation to occure? 2. The range of temperatures where the Al-Si is soluble? 3. The range of ...
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Question about liquid-phase in P-T Diagram

Currently, I have been learning about P-T diagrams and vapour pressure and I have a question that seems like it should have a simple explanation yet I am not able to understand it. Taking the P-T ...
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Is liquid water in equilibrium with water vapor at room temperature?

This question was inspired by Why does liquid water form when we exhale on a mirror?. This question is different from Why does water evaporate at room temperature? because it asks about whether an ...
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Why does liquid water form when we exhale on a mirror?

In the descriptions below, I always assume external pressure to be constant at 1 atm, the condition where daily observations are made. 1) When I exhale on a mirror, liquid water forms on the mirror. ...
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Is there any sort of correlation between melting point and the degrees of freedom for the molecules of a substance?

Suppose I had a solid whose molecules did not have rotational freedom. But if I were able to make it so that the molecules had rotational freedom ceteris paribus, is there a way to tell how the ...
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Reaction that will produce a silica coating (glaze)

The normal way to create a coating of pure silicon dioxide glaze is to coat the object to be glazed in a slurry of silica particles and then put it in a kiln. However, if I have an object that is too ...
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Chemical that won't freeze below melting point

I have an organic chemical (can't say due to an NDA) that has a nominal melting point of 28 °C. When I raise it above this temperature, it melts, but then it will stay a liquid indefinitely at lab ...
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Solubility of solids in liquids

How does crystallisation happen and why? I have been told that when a solid is dissolved in a liquid solvent, an equilibrium is set up between processes of dissolution and crystallisation. But if ...
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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 ...
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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 ...
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1answer
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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 ...
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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, ...
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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 ...
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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}+...
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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 ...
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2answers
118 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? ...
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1answer
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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 ...
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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 ...
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1answer
135 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. Facts and definitions freezing point: "The ...
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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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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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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 ...
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1answer
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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 ...
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1answer
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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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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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209 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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1answer
60 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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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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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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225 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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157 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 ...
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1answer
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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 ...
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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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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?
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480 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 ...