Questions tagged [mixtures]

Questions related to the physical combination of two or more substances on which the identities are retained and are mixed in the form of solutions, suspensions, and colloids.

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Why do impurities lower the melting point of an isolated substance?

It is known that impurities in a desired isolated product lower the melting point of the mixture, even if the impurities' melting point is much higher than the desired product. Why is that so?
LanceLafontaine's user avatar
24 votes
1 answer
6k views

How does oobleck work?

Oobleck is basically a mixture of cornstarch and water. It has the interesting property of going hard when pressure is applied. For example, it feels like a liquid when you swirl your fingers through ...
ManishEarth's user avatar
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Is it possible for a compound to be soluble in a mixture of solvents but not the individual solvents?

Some weeks ago one of my friend needed to use turpentine. As a good but ignorant chemist on that point I did some research about it. I found (at the beginning) in the French wikipedia page of ...
ParaH2's user avatar
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20 votes
2 answers
2k views

Can a stoichiometric mixture of oxygen and methane exist as a liquid at standard pressure and some (low) temperature?

This answer to the question Pre-mixing cryogenic fuels and using only one fuel tank written by a non-chemist (me) begins with: At STP: LOX's boiling point is 90.19 K Methane's freezing point is 90....
uhoh's user avatar
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19 votes
5 answers
14k views

Un-denaturing industrial alcohol

I have a question regarding the denaturation of industrial ethanol with methanol to discourage its consumption. The boiling point of methanol is 64.7 °C, while the boiling point of ethanol is 78.37 °...
René's user avatar
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18 votes
4 answers
3k views

Is enthalpy additive in mixing?

When mixing two fluids of different composition at constant pressure when no heat can escape, is the enthalpy additive? If not, how to compute the enthalpy of the mixture resulting from mixing two ...
Arnold Neumaier's user avatar
15 votes
3 answers
4k views

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 $p = p^*_A + p^*_b$,...
TheLearner's user avatar
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15 votes
2 answers
5k views

Why does the ink on my whiteboard move?

...or at least I thought so, when I saw that the ink that was on my whiteboard last night became really messed up the next day. The image below shows my whiteboard before (on the left) and after (on ...
rhyaeris's user avatar
  • 303
15 votes
1 answer
819 views

Mixing two containers of each water and ethanol to varying degrees of purity

In the following question, the water/wine mixing problem was recast in chemical terms. However, partial molar volumes can make this a much more challenging problem than it appears on the surface. ...
Ben Norris's user avatar
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14 votes
3 answers
29k views

Are all homogeneous mixtures just solutions?

Or can there be a homogeneous mixture that is not a solution?
la.vie.en.rose's user avatar
13 votes
3 answers
147k views

What is the carbon dioxide content of a soda can or bottle?

I sort of know how carbonated beverages are carbonated: a lot of $\ce{CO2}$ gets pushed into the liquid, and the container is sealed. There are at least two things I don't know. First, how much carbon ...
Colin McFaul's user avatar
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13 votes
2 answers
693 views

Do azeotropic mixtures evaporate proportionally?

Do azeotropes evaporate, without boiling, in proportionate amounts, or does this property describe their behaviour only at boiling point? Concretely, if 91% isopropyl alcohol/water (by volume, i.e. an ...
OJFord's user avatar
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12 votes
3 answers
20k views

How does dimethylsulfoxide serve as a cryoprotectant?

In cell culture, dimethylsulfoxide (DMSO) is added to prevent the formation of ice crystals which may lyse the cells. Exactly how does dimethylsulfoxide act as a cryoprotectant?
bobthejoe's user avatar
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11 votes
2 answers
1k views

Why would there be a non-zero Gibbs energy of mixing for ideal gases?

When two ideal gases $\ce{A}$ and $\ce{B}$ mix, they don't interact. The chemical potential of each gas is independent of the other, e.g. for $\ce{A}$: $$\mu_\ce{A} = \mu_\ce{A}^\circ + R T \ln \frac{...
Karsten's user avatar
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9 votes
6 answers
5k views

A quick method for separating liquids?

I'm looking for a way to take 3 separate liquids (liquids which function as paint -- they will all be different colors), put them together into a container, and then rapidly separate them back to ...
temporary_user_name's user avatar
8 votes
1 answer
1k views

How to separate paracetamol and caffeine?

How do you separate paracetamol and caffeine using high-school laboratory equipment? I was thinking about using the fact that paracetamol has a lower melting point (169 °C) compared to caffeine (...
Jingjie Yang's user avatar
7 votes
1 answer
2k views

Is the density of a two-component mixture always between the densities of its individual components?

There exist eutectic mixtures, in which the freezing point of the mixture is below those of either component of the mixture, i.e., the freezing point of the mixture is not intermediate between that of ...
TheEnvironmentalist's user avatar
7 votes
1 answer
4k views

Shortcut for calculating pH of mixtures

My teacher gave me a shortcut to calculate the resultant pH if 2 or 3 solutions are mixed, which are relevant only if the difference between the pH of individual solutions is 1. If there are two ...
Rohinb97's user avatar
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7 votes
1 answer
3k views

Why does tea dissolve better when put in water rather than milk?

I sometimes drink tea with or without milk. What I have noticed is that when I dip the bag in water the tea spreads out evenly and I have a cup of tea in like 5 minutes. But when I do the same with ...
Anarach's user avatar
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7 votes
1 answer
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Heat capacity of mixtures

After reading this recent question I was interested in how to calculate the specific heat capacity of a mixture based on the specific heat capacities of its components. According to this website the ...
bon's user avatar
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7 votes
2 answers
2k views

Miscibility of Molten Metals

While reading about the size of atoms and ions of the Group 1 elements in the textbook "Concise Inorganic Chemistry" by JD Lee, I came across this line: The Li+ is much smaller than the other ions. ...
tkhanna42's user avatar
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7 votes
0 answers
655 views

Dry water using graphite

Dry water or "powdered water" is essentially a bunch of extremely small water droplets surrounded by $\ce{SiO2}$. Some time ago, I was messing around and mixed some powdered graphite with water. (The ...
sadljkfhalskdjfh's user avatar
6 votes
3 answers
1k views

Does stoichiometric gas mixture produce the highest explosion pressure (or energy) compared with other explosive limit mixture?

I understand that a stoichiometric mixture contains a balanced mixture of air and fuel and both fuel and air are completed consumed. For example, the ideal stoichiometric mixture for propane is ...
William Chao's user avatar
6 votes
3 answers
3k views

Why does Coca-Cola Zero Sugar Contain Sodium Despite no Sodium Ingredients?

According to the Coca-Cola website and every label I read, Coca-Cola Zero Sugar is a mixture of organic compounds: CARBONATED WATER (OC(OH)₂), CARAMEL COLOR (Various sugars), PHOSPHORIC ACID (H₃PO₄...
Rob Perkins's user avatar
6 votes
2 answers
3k views

Reactions between enantiomers in a racemic mixture

As a follow up to this question I started thinking about another question. During racemization, enantiomers are mixed in a equal ratios to form an optically inactive mixture. What type of reactions ...
tkhanna42's user avatar
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6 votes
1 answer
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What is the solvent and what is the solute?

This question is and I am learning about mixtures, solutions, solutes, solvents, and other terms related to these words. I know that a solute is the substance being mixed with or dissolved into the ...
ShadowWolf's user avatar
6 votes
1 answer
966 views

What is 'spray foam' or 'expanding foam'?

At the wikipedia are: Spray foam (expanding foam in the UK) is a chemical product created by two materials, isocyanate and polyol resin, which react when mixed with each other and expand up to 30-60 ...
Imyaf's user avatar
  • 71
6 votes
3 answers
26k views

Determining weight-percent methanol in water from specific gravity and temperature

The company I'm working with uses a fuel mixture of methanol and water. We use a hydrometer to measure specific gravity, in order to test the composition of fuel received from our suppliers. To ...
nhinkle's user avatar
  • 161
6 votes
1 answer
2k views

What household substances could be distilled

I'm looking to experiment with distillation to have a basis for understanding the theory slightly better, and get a better feel for it. I'm hoping for some suggestions as to what I could try ...
Jodes's user avatar
  • 461
6 votes
2 answers
2k views

How to determine the vapor pressure of a glycerine and propylene glycol mixture?

I am looking to calculate the minimum heat needed to create vapor from a specific mixture. I have a mixture of 60 % $\ce{C3H8O3}$ (glycerine) and 40 % $\ce{C3H8O2} $ (propylene glycol, propane-1,2-...
brandon-estrella-dev's user avatar
6 votes
1 answer
376 views

How Would A Vast Mixture (Like an Ocean) of Ammonia-Water Behave in Terms of Evaporation and Freezing?

First, I'll go ahead and say I'm not very versed in chemistry. My question comes from my interest in planetary-sciences, specifically the speculation that there are likely exoplanets and moons with ...
n_bandit's user avatar
  • 247
6 votes
1 answer
4k views

Chemical potential of mixtures

I feel that there are very few textbooks that treat the chemical potential of mixtures in an understandable clear way, which is why I wanted to ask here about certain things. Although I do not have a ...
Xin Wang's user avatar
  • 161
6 votes
0 answers
404 views

Density of non-ideal vapor mixtures

I'm looking for a reasonably accurate density of a mixture of two gases that act quite unlike ideal gases (generally steam and water-miscible solvents). We can get a first order estimate by taking a ...
ericksonla's user avatar
  • 1,690
5 votes
1 answer
2k views

Strong exothermic mixing of two 'safe' liquids

I have read (thanks to Stack Exchange) that mixing water and sulfuric acid is exothermic, as is NaOH and HCl. Are there two 'safe' liquids that can be mixed and produce anywhere near the same amount ...
fennex's user avatar
  • 69
5 votes
2 answers
787 views

Name of particles in a suspension

What is the proper name given to the particles in a suspension? Suspensae perhaps? When these particles are brought out of suspension, and precipitate down to the bottom of the mixture, what is that ...
hotmeatballsoup's user avatar
5 votes
3 answers
10k views

What is the entropy of mixing of two ideal gases starting out with different pressures?

The entropy of mixing of ideal gas is given by this equation: $\Delta S_{mix} = -nR(x_1\ln x_1 + x_2\ln x_2)$ Does this equation works only when the initial conditions of both compartments are at ...
t.c's user avatar
  • 1,305
5 votes
2 answers
3k views

How to determine a Reynolds number for mixture of 2 liquids

I'm experimenting with synthesis in microreactors and I'm using 2 reactants. I'd like to estimate the Reynolds number of the flow containing two miscible fluids. I have the values of their properties (...
Ezze's user avatar
  • 53
5 votes
2 answers
2k views

A solution is cloudy at lower concentration and becomes clear at higher concentration. Why?

This might be just an "everyday life science" question. I am a university professor but not in chemistry so please educate me. Today I was adding some floor cleaner formula to water as ...
max sim's user avatar
  • 59
5 votes
3 answers
5k views

How to Make Ferrofluid in a Bottle

I am trying to accomplish the very famous magnetic Ferrofluid in a bottle aka office desk toy. Before anyone suggest to buy online, I would like to make it myself and learn the whole process VS store ...
aj Saini's user avatar
5 votes
1 answer
5k views

Is there anything that doesn't mix with water or oil?

It's well known that water and oil don't mix, and if you put them together, the oil will float on top of the water in a distinct layer. My understanding is that this is because water is polar due to ...
Zephyr's user avatar
  • 153
5 votes
3 answers
2k views

What is the molecular interpretation of Raoult's law?

I was reading about Raoult's law which states: It states that the partial vapour pressure of each component of an ideal mixture of liquids is equal to the vapour pressure of the pure component ...
user avatar
5 votes
1 answer
190 views

How to quantify amount of pigments in plant leaves?

Using thin-layer chromatography, it is possible to see what pigments plant leaves contain. For example, I can test whether there are chlorophyll a or b, carotenoids, or anthocyanins. What kind of ...
kaea's user avatar
  • 51
5 votes
1 answer
108 views

Combination of polydisperse polymer mixtures

Say I'm given a mixture of batches of polydisperse polymers. I know the weight $w$, the number average $ \bar M_n$, and the weight average $ \bar M_w$ of each batch that was added to the final mixture....
Z. E.'s user avatar
  • 63
5 votes
0 answers
129 views

Raoult's law: is the molar fraction the molar fraction in the entire system?

I have two physical chemistry textbooks, one by Atkins and one by Levine, which seem to differ in their notation used when describing Raoult's law. Atkins talks about the molar fraction term in ...
DLV's user avatar
  • 813
4 votes
2 answers
7k views

Why water can't mix with oil or cooking oil?

Why water can't mix with oil or cooking oil (both saturated and unsaturated)?
lambda23's user avatar
  • 2,510
4 votes
2 answers
584 views

What is the entropy of mixing a gas into the whole atmosphere?

Suppose I release 1 mole of pure argon into the atmosphere. What is the entropy of mixing? The equations I have found seem to only apply to the case of a fixed volume. Should I use an estimate of the ...
Doug McClean's user avatar
4 votes
1 answer
1k views

Why is glass a mixture and not a solution?

While studying mixtures and solutions, I read that glass is a mixture and not a solution. Then I searched over the Internet about it, but I got the same answer that it is a homogenous mixture. But ...
Harjot Dhillon's user avatar
4 votes
1 answer
6k views

Explain volume contraction in mixtures of alcohol and water

Could someone explain why volume contraction occurs when you mix an alcohol such as ethanol with water in relation hydrogen bonding and the dipole-dipole forces?
icin's user avatar
  • 49
4 votes
1 answer
65 views

Which is the suitable process for ball milling?

Why do we mainly choose the wet ball milling process in spite of dry ball milling process? Both processes are used to make a homogeneous mixture of different compounds.
amusing_saha's user avatar
4 votes
2 answers
2k views

How to calculate the partial pressure of oxygen in this mixture of oxygen and argon?

A $\pu{19.3 g}$ mixture of oxygen and argon is found to occupy a volume of $\pu{16.2 L}$ when measured at $\pu{675.9 mmHg}$ and $\pu{43.4 ^\circ{}C}$. What is the partial pressure of oxygen in this ...
Maher's user avatar
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