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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40
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3answers
13k views

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?
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1answer
5k 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 ...
21
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1answer
1k views

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 ...
20
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2answers
961 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....
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6answers
7k 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 °...
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5answers
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 ...
14
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3answers
3k 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 $p = p^*_A + p^*_b$,...
14
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1answer
703 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. ...
13
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3answers
24k views

Are all homogeneous mixtures just solutions?

Or can there be a homogeneous mixture that is not a solution?
13
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2answers
2k 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 ...
11
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3answers
124k 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 ...
10
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2answers
16k 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?
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6answers
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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 ...
8
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1answer
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 ...
8
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1answer
514 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 (...
7
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1answer
255 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 ...
7
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2answers
1k 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. ...
7
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0answers
529 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 ...
6
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3answers
22k 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 ...
6
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1answer
1k 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 ...
6
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2answers
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-...
6
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1answer
116 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 ...
6
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1answer
3k 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 ...
6
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0answers
317 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 ...
5
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1answer
1k 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 ...
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2answers
2k 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 ...
5
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2answers
2k 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 (...
5
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1answer
18k views

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 ...
5
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1answer
32k views

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 ...
5
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1answer
152 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 ...
5
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0answers
119 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 ...
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2answers
5k 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)?
4
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2answers
414 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 ...
4
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3answers
564 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...
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2answers
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 ...
4
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1answer
818 views

Miscibility of Hexane and Ethanol (Anhydrous vs 96%)

In my lab, I mixed 8:2 (mass:mass) of Hexane:Ethanol (Hexane: 0 ppm of water content, ...
4
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1answer
3k 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 ...
4
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2answers
5k views

Strictly speaking, is air homogeneous?

Why would air be considered homogeneous in its gaseous state (by Wikipedia and several other sources) even though its concentration keeps varying with time? A homogeneous fluid as i think of it is as ...
4
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1answer
438 views

Does adsorption occur between liquids?

While reading a paper in a field other than chemistry, the author mentions a phenomena that he labelled "adsorption" and describes it as follows: ...I am told (though I do not know which liquids ...
4
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2answers
480 views

Gold nanoparticles in a water/oil environment

I am currently investigating the assembly of gold nanoparticles in a mixture of water and oil. The thing is the following: If we have gold nanoparticles (35nm diameter) dispersed in water and we put ...
4
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1answer
147 views

Viscosity of two different solutions

Suppose that I have 10 kg of plastic/polymer that is non solvable in water. I then divide the plastic/polymer into two equal parts. Let us name the parts A and B in order to identify them. I then ...
4
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2answers
1k 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 ...
4
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1answer
31 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....
4
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1answer
683 views

Titration to determine the amount of hydrogen peroxide

I have a mixture of sodium carbonate, sodium bicarbonate, ammonium carbonate, copper (II) sulfate, hydrogen peroxide, and sulfuric acid. I'm titrating potassium permanganate against this mixture to ...
4
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1answer
2k views

Total pressure in a chamber calculation

I have a chamber containing two different gases and a liquid which needs to be heated at a certain temperature to bring it to vapor state. I have worked out that we can calculate the total pressure ...
3
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3answers
438 views

What does my textbook mean by saying this about petroleum?

It reads: Petroleum consists of crude oil and natural gas and contains a mixture of up to 300 hydrocarbons, including sulfur and nitrogen compounds. It is formed over thousands of years from the ...
3
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2answers
856 views

Interpretation of miscibility curves

I stumbled across miscibility curves in the section Solubility of Liquids in Liquids (Organic Chemistry, by Wallwork and Grant) today. I'm not sure if my problem is with the way the content was laid ...
3
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2answers
213 views

Is this relation in case of a mixture of ideal gases valid?

I came across the following relation in a book (written as a fact, with no proof), for a mixture of ideal gases both at the same pressure and temperature. The final volume of the mixture of gases ...
3
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1answer
45 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.
3
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2answers
230 views

Calculating the dissociation constant of one acid in a mixture

A solution contains $\pu{0.09 M}~\ce{HCl}, \pu{0.09 M}~\ce{CHCl2COOH}$ and $\pu{0.1 M}~\ce{CH3COOH}$. The $\mathrm{pH}$ of the solution is $1$. Given that the $K_\mathrm{a}$ of acetic acid is $10^{-5}$...