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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.

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287 views

Are allotropes of sulfur two different phases?

Monoclinic sulfur and rhombic sulfur are two allotropes of sulfur. In phase equilibria, part of the system that is having distinct boundary, mechanically separable and different chemical or physical ...
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1answer
4k views

Can a liquid turn to a solid by applying pressure?

When pressure increases, volume decreases. If an extremely high pressure is applied to a liquid, is it possible to reduce it's volume to an extent where the molecules are very tight together, hence ...
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2answers
4k views

Why is the plateau on a heating curve in equilibrium?

From the interval of 100 to 140 minutes, why is the substance in equilibrium? I believe it's because at this interval, freezing and melting begin to occur at the same rate and, when two opposing ...
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1answer
154 views

DSC Metal hysteresis (melt/cryst)

So we were analyzing Polymers using DSC and calibrated the system using Indium. I expected it to be a single transition only as Indium only has 1 known crystal structure and as I never worked with DSC ...
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100 views

Properties of metallic hydrogen

Given the possibility that metallic hydrogen may have recently been produced, and the massive media bloviation that followed, I am curious about some of the "properties" that I heard from multiple ...
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0answers
290 views

Will the DNA in a solution containing DNA and water evaporate?

I understand that water will evaporate as long as the partial pressure of water vapor is lower than equilibrium vapor pressure. But I am not quite sure if DNA in a solution can, like water molecules, ...
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1answer
193 views

Why are there two vertical axes in the iron-carbon diagram? [closed]

More precisely, why do we have two axes that represent the same parameter, which is temperature?
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1k views

Why is phenol a solid at room temperature?

The commonly cited reason is inter-molecular hydrogen bonding. But won't the hydrogen bonding in phenol be weaker than that of most alcohols because of resonance-effect? And yet, alcohols with ...
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1answer
34 views

Is this a homogenous reaction?

$$\ce{HCl(aq) + NaOH(aq) -> NaCl(aq) + H2O(l)}$$ Would this reaction be considered homogenous even though there is a liquid in the products?
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1answer
376 views

Hydrogen Bonding in Water Phase Changes

How is the disparity between the heat of fusion and the heat of vaporization for $\ce{H2O}$ best explained? A) It takes more hydrogen bonds for water to fuse than it does to vaporize. B) Water ...
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2answers
378 views

Phase Diagrams and Equilibrium

In this link http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/phase.php It says (in the latter part ) that for all combinations of Pressure and Temperature along line BC the rate of ...
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1answer
114 views

Does mercury chloride (ii) evaporate at room temperature? [closed]

if you leave mercury chloride (ii) exposed to air in a room does it evaporate to any significant level which can cause toxicity?
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0answers
75 views

Does this freezing point depression problem make sense?

The solvent is water. Pure water has a freezing point of 0 degrees Celsius. How come, in this problem, the addition of solute results in an elevation of the freezing point from 0 to 0.46 degrees C? Is ...
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1answer
190 views

How many particles are necessary to observe a well-defined state of matter?

The three ordinary states of matter $-$ solid, liquid, gas $-$ can usually be distinguished by a function of the strength of interparticular forces and distance. A shorter distance and a stronger ...
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1answer
425 views

What happens when a body of water and a pice of ice are placed in a pricessly controlled zero degree environment

My understanding is, if you put ice into a >0 degrees environment, it will be 0 degrees as it melts and if you put water into a <0 degree environment, it will 0 degrees as it freezes. but what ...
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0answers
56 views

Phase description for a substance dissolved in a solvent other than water?

I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for ...
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0answers
31 views

Melting point of Ammonia at 143 psia

I'm currently working on a theory involving ammonia based life, but I need information about the freezing point of ammonia at high pressure to determine several ecological limitations at hand. I've ...
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1answer
232 views

What is pure oxygen (gas) density as a function of T or P?

I'm looking for a set of data (ideally graphed) of $\ce{O2}$ density as a function of $T$ or $p$ (with constant $p$ or $T$, respectively). The best I've found is this 1948 paper which provides an ...
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0answers
83 views

Thermodynamics - Number Of Component [closed]

$\ce{CaCO3(s) -> CaO(s) + CO2(aq)}$ It is said that the number of constituents for this reaction is three . I think number of constituents refer to the number of different elements in the system ....
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1answer
3k views

Significance of phase of atomic orbitals

I am learning about orbitals and bonding and antibonding MOs. So far, I know that when you combine s orbitals, you form both bonding and antibonding MOs- bonding when the wavefunctions are added in ...
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1answer
1k views

Will fluoride evaporate from tap water at the same rate as chlorine

Chlorine evaporation is an overnight process from standing tap water in a gallon pan. Does fluoride evaporate in the same way/rate?
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0answers
43 views

Calculating relative molecular mass given mass of solute and solvent, as well as freezing point depression, but no cryoscopic constant? [closed]

Find RMM of anthracene given that when 0.813g is dissolved in 45g of benzene. freezing point of depression is 0.51 degrees celsius.
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4answers
5k views

What happens to the molecules of a liquid when it evaporates?

Let's say I spill liquid on some fabric or on a impermeable material like a countertop. Eventually, the liquid stops being a liquid and we say it has "dried", but what happened to the molecules? Did ...
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3answers
2k views

Does naphthalene in moth balls really sublimate or does it evaporate?

The triple point of naphthalene is $\pu{-56 °C}, \pu{1.05 kPa}$ (which is much less than $\pu{1 atm}$). So how can a naphthalene ball sublimate at $\pu{1 atm}$, when considering that its melting point ...
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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 ...
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1answer
329 views

How are bubbles formed when heating water? [closed]

My thinking is that bubbles are formed due to the dissolved gases in water. Consequently, upon heating, bubbles are formed and do not remain intact with water molecules, and thus the bubbles are ...
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1answer
41 views

How do I select a sub-freezing temperature for my experiment that will allow the formation of frost, but not supercooled liquid water (rime)

I once conducted a set of experiments in which I had to form ice by direct vapor deposition (not condensation of liquid water followed by freezing, aka riming) onto a Peltier-cooled glass-coated ...
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0answers
74 views

Why is it impossible to liquefy a gas with only pressure? [duplicate]

Why is it impossible to turn it to liquid by using only pressure after it reaches critical temperature? What happens in the molecular level? If we put enough pressure, the molecules are supposed to ...
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1answer
144 views

Liquid water below freezing temperature

I got in my car this morning and the temperature read 13 F (that's around -10.5 C.) While driving down the road, I noticed a bottle of water in my cup holder was frozen solid as expected. Another ...
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1answer
4k views

At the freezing point, why is the vapor pressure of the liquid phase equal to the vapor pressure of the solid phase?

At the freezing point of a substance, the solid phase is in dynamic equilibrium with the liquid phase. My textbook defines the freezing point of a substance as: "the temperature at which the vapor ...
3
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1answer
635 views

Reaction speed with solids

It seems that reaction rate is defined as change of concentration over time and the speed doesn’t change if you add more solid. But imagine we have a cube (1 kg) of $\ce{CaCO3}$ that yields 1 mole $\...
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1answer
173 views

Reasons for existence of eutectic point for alloy systems

Why does a eutectic point exist for a system of alloy ? Why is it that there is such a definite ratio of composition at which this occurs ?
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1answer
82 views

Can every chemical compound be melted?

Are there any chemical compounds that disintegrate (without going into other chemical reactions; let's say in a vacuum) before reaching a melting temperature?
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52 views

Is it possible to supercool hydrated salts like magnesium nitrate hexahydrate supercool just like for sodium acetate trihydrate?

Recently I stumbled upon the phenomenon of supercooling. I know that you can do this with water as well as with some phase change materials, like sodium acetate trihydrate (from the wintersport ...
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0answers
243 views

Water condensation above dew point

Anyone who stores rust-prone instruments knows that even in temperature-controlled air spaces rust can form on uncoated steel. Since rust requires water, this suggests that water will condense out of ...
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1answer
389 views

Why Does an Area in Phase Diagram Considered as Having Degree Of Freedom=1?

Why did the area in the center are Considered as Having 1 Degree Of Freedom. Aren't we able to change the concentration and the temperature at the sametime without changing the Phase? Here is the ...
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1answer
4k views

What phase of matter is shaving cream? [closed]

Our teacher asked us if shaving cream is a solid, liquid, or gas. She didn't quite know herself.
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1answer
149 views

Validating Phase Diagram of a mixture

In lab I did several different runs to create a phase diagram for the mixture between biphenyl and naphthalene. My phase diagram is attached, just for visual purposes. My question is I'm supposed to ...
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2answers
541 views

Why all objects do not melt and liquefy when heated suficiently?

Certain objects such as metals, glass, plastic, sugar etc. melt when heated above a certain temperature but other materials such as a piece of wood, paper, a piece of rock etc. do not. Why is that?
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1answer
147 views

Nucleation and Phase Equilibrium at the Melting Temperature

I used to think that at the melting point, the solid and liquid phases are in equilibrium. That’s because the Gibbs free energy change for the transformation is 0, as is characteristic of equilibria. ...
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1answer
246 views

Confusion about boiling point and vapor pressure [duplicate]

It is said that a liquid boils when its vapor pressure equals to the external pressure of its environment (e.g. atmospheric pressure). That’s because the bubbles of water vapor that form will be ...
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0answers
66 views

Solid/Liquid/Gas Phase Change Energy

If energy is put into a solid, for example ice, and the phase changes, where does the energy go? Does it change the length between molecular bonds or get absorbed when the crystalline bonds break?
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0answers
675 views

How can I estimate the triple point of a substance given the densities of its liquid and solid phases and its enthalpies of fusion and vaporization?

I am trying to find the triple point of H2O given only the densities of water and ice, the enthalpy of vaporization, and the enthalpy of fusion. I know that I should be able to use some combination ...
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0answers
109 views

Effects of inert gas on heterogenous equilibrium

What is the effect of the presence of an inert gas on a reversible reaction that was in more than one phase, such as a decomposition reaction? If a solid or liquid or compound in aqueous solution ...
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3answers
1k views

Will supercritical nitrogen stay supercritical if we raise temperature and pressure high above critical values?

Nitrogen's critical temperature is -146.96 °C and critical pressure 33.96 bar. If we maintain nitrogen at 220 bar and 400 °C, what will be the state of $\ce{N2}$? Will it be still supercritical? I ...
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1answer
27 views

Is there a T-V or P-V chart relating LiBr temperatures for recovery?

I'm working on a project and would like to consider a LiBr solution to be used as a desiccant. I don't know however the temperature of air vs pressure to recover it. I was thinking of using a nozzle/...
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1answer
92 views

Vacuum at different altitude

I have tried to find this searching the internet and I am not sure if I understand it. I want to turn water from solid to gas without going into the liquid phase - Sublimation. The altitude above sea ...
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1answer
14k views

Why is the boiling point of water and ammonia so different?

Boiling point of water is 100 degrees Celsius, while boiling point of ammonia is minus 33 degrees Celsius, which makes 133 degrees difference. Now when we discuss value of boiling point, we also say ...
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3answers
3k views

Is a liquid in a container always in equilibrium with its vapour?

This is essentially a question about the meaning and significance of the term vapour pressure (or vapor pressure if you're American). From what I understand a liquid in a container will have a certain ...
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1answer
44 views

Can course salt melt into water [closed]

What can cause course salt to melt? If you put it on a flat surface, can it melt on its own into water? What causes this reaction to make the salt melt?