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Technically, alcohol is the name of a class of organic compounds containing one or several hydroxyl groups. Colloquially, the term "alcohol" is understood as you have described: A solution (of varying degree of purity) of ethanol and water. Pure ethanol is impossible to create via the traditional method of purification (atmospheric distillation) as the ...

31

When you add salt to an ice cube, you end up with an ice cube whose temperature is above its melting point. This ice cube will do what any ice cube above its melting point will do: it will melt. As it melts, it cools down, since energy is being used to break bonds in the solid state. (Note that the above point can be confusing if you're new to thinking ...

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Saturating a liquid with one solute does not mean that the liquid will no longer dissolve another solute. However, you can expect the solubility of the second solute to be different, generally lower, than in the neat solvent. One relevant concept here (though not specifically applicable to sucrose), in the case of ionic solutes, is the common-ion effect. ...

24

You could imagine stirring the sugar enough for the water molecules to be uniformly distributed throughout - it would then be homogeneous. However, even then, to refer to the mixture as a solution of water in sugar is unhelpful, not least because referring to a slightly damp solid as a solution will only confuse. A definition needs to be useful, as well ...

21

As it happens, the enthalpy of solution of $\ce{NaCl}$ in water (that is, the energy change associated with the dissolution of sodium chloride crystals in water) at standard conditions is very slightly positive, i.e., it is an endothermic process. At a constant temperature and pressure, these kinds of thermodynamic processes are dictated by the change in ...

21

The analogy with a proton is actually a good one if you are careful to remember that an electron is nearly 2000 times lighter than a proton. What does that mean? It means that despite the fact that an electron is very "small", the electron is actually going to be very large because lighter particles will tend to spread out and have a much more diffuse ...

20

To directly address where the phrase comes from: Water is called the "universal solvent" because it dissolves more substances than any other liquid. -USGS What are ideal qualities of solvent? The strength of a solvent can be attributed to the strength of its intermolecular forces like london forces, dipole-dipole forces, ion-induced dipole, and hydrogen ...

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TL;DR: Water is incredibly easy to get and work with. In full Water is a good solvent for polar compounds[citation needed], and the reasons for this are laid out pretty well by John Snow, but that's not really what makes it the universal solvent. Instead, a series of other, incidental properties makes it a popular choice: Availability There's a lot of ...

20

I think you are looking at the problem from slightly the wrong angle. The central quantity when dealing with colligative properties is entropy and not solute-solvent or solvent-solvent molecule interactions. Of course the interactions are important in the sense that they affect the entropy but since we are dealing with thermodynamics here the way you think ...

19

This is standard for purifying substances. To wash means to add your product solution to an aqueous solution (or just water, but frequently a saturated solution) to a separatory funnel. After shaking, you drain the lower layer (which is usually aqueous). This process removes water soluble impurities. This is frequently repeated. Drying is accomplished by ...

18

Quoting a reddit post from chemist nallen: The short answer is that the dirt and oils from your hair compete for the surfactants making them less available to form lather, which is small bubbles. To better understand the mode of action, you have to know a bit about the formulation of shampoos and the nature of dirt and oils. Dirts and oils deposit on hair ...

18

I'll try an answer to this question because I watched this video a while back and did a bit of reading on it at the time and I think I understand the big picture. The problem is that these solvated electrons are very complicated things, and do not lend themselves to the traditional ways that chemists would like to think about things. For that reason, there ...

18

When most people think of the term solvent, a liquid medium comes to mind; however, in the technical sense of the definition, this does not have to be the case. Here is the definition of a solution present in the IUPAC gold book: A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the ...

17

This is an example of electrostriction - see, for example, this paper for a full explanation. In short, the solvent molecules become more ordered in the vicinity of dissolved (charged) ions and less ordered as we go further away from the dissolved (charged) ions. The increase of solvent density near the ions is offset by the decrease of bulk density in the ...

17

Both answers are right. In the IUPAC Gold Book it states A liquid or solid phase containing more than one substance, when for convenience one (or more) substance, which is called the solvent, is treated differently from the other substances, which are called solutes. So either way can be used, but it is usually more conventional to call the ...

17

There's a NASA report that looks into this: "ON THE SOLUBILITIES AND RATES OF SOLUTION OF GASES IN LIQUID METHANE", Hibbard and Evans, 1968 and concludes that such mixtures are possible. Starting on page 8: Figure 5(a) presents the curves for oxygen, argon, carbon monoxide, and nitrogen. Also shown are the two experimental values for nitrogen. ...

16

The purification that occurs when an aqueous solution freezes is called Fractional Freezing and is based on the idea that impurities of a solvent (and this can be any solvent, not just water) have a much lower solubility in the solid phase of the solvent relative to the liquid phase. Several techniques for performing fractional freezing for purification ...

16

Just to provide an alternative answer: Consider a solvent miscibility table like the one linked. What is the least miscibile solvent? Water! Water is the worst solvent. Water is immiscible with 17 out of 30 of the other listed solvents. There are 6 solvents in the table which are miscible with all the other solvents: ethanol, acetone, tetrahydrofuran, n-...

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Apart from the methods, Ringo already described, you can do a few other tests. Aluminium This is loosely translated from the German chemgapedia.de. Look at the pretty pictures. Probably the easiest test you can do is reacting it with Morin in ethanoic acidic medium. It forms a yellow-green chelate complex, which has strong fluorescence under UV light. The ...

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Actually, sodium chloride added to water will decrease the volume of the solution, up to around 2% for a saturated solution. Even when fully saturated, that's not a big change, so you may not have been able to observe it without something with a narrow neck like a volumetric flask. If you start with a large volume and carefully mark the level, you should be ...

16

Well, I went and searched for the solubility of oxygen in water and oil, and found this summary paper on the NIST web site: "The Solubility of Oxygen and Ozone in Liquids" by Battino, Rettich and Tominaga, J. Phys. Chem.Ref. Data., vol 12, no. 2, 1983. Conveniently, the paper gives solubility data for oxygen in both water and olive oil. The solubility is ...

16

The short answer is: yes, this is possible. Unfortunately, solubility is a fairly complex phenomenon to explain simply. Let's start with some examples where solubility is higher in a binary mixture than either solvent alone. For a solid-liquid-liquid example: phenanthrene-cyclohexane-diiodomethane.[1] For a liquid-liquid-liquid example like the one you were ...

15

Foreword This topic is treated in most books and sites so I've tried to explain it to you in a more unusual and friendly way to grasp the concept but maybe the canonicals explanations are more suited for exams and serious conversation. First step idealize and simplify the Raoult law You can see Raoult law as the most basic attempt to predict the partial ...

15

In general, salt (particularly NaCl) will increase the rate of corrosion (rusting). To understand why, consider metallic iron $\ce{Fe}$ which rusts (oxidises) to iron(II) oxide $\ce{Fe2O3}$ in the presence of oxygen $\ce{O2}$ and water $\ce{H2O}$. $$\ce{4Fe +3O2 +6H2O->4Fe(OH)3}$$ Corrosion (rust) is a 'redox' reaction, which means it involves ...

15

In the first equation, $\ce{Fe}$ is oxidised to $\ce{Fe^2+}$ by $\ce{H+}$; the $\ce{SO4^2-}$ ions play no role in the reaction. You could replace $\ce{H2SO4}$ with $\ce{HCl}$ and get the same reaction. In the second equation, the same oxidation of $\ce{Fe}$ to $\ce{Fe^2+}$ by $\ce{H+}$ also occurs. However, on top of that, some of the $\ce{SO4^2-}$ ions are ...

14

The keyword is that the salt dissolves. Dissolution entails at least two steps: 1) Overcoming solvent-solvent interactions and bonds. An extreme example: your dinner plate doesn't dissolve in your kitchen table. One reason is that there is an extremely high energy barrier to overcoming the hypothetical solvent's (in this case, the kitchen table's) ...

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This is not a general rule. Much like with acids for some bases we write progressive capture of one proton at a time. It all depends on the nature of the acid/base. In the case of $\ce{Ca(OH)2}$ you don’t have a molecule like $\ce{HO-Ca-OH}$ or something like you can assume for $\ce{HO-SO2-OH}$ (sulfuric acid). Rather, you have an ionic compound composed of ...

14

Can sugars dissolve in liquid ammonia? Yes, according to Ref.1, liquid ammonia is used to extract sugars in sugar-beet chips: 5.88 kilograms of sugar-beet chips having a moisture content of 5.4 percent and a saccharose content of 68 percent (calculated on the dried substance) are treated in an autoclave of 50-litre capacity with 18 kilograms of liquid ...

13

Homogeneous and heterogeneous classifications are scale-dependent. What we mean when we say a mixture is homogeneous is that there are no visible phase differences on the scale of interest. For example, milk (when homogenized) and lotions are both examples of colloidal suspensions. There are no phase differences at the human scale, but neither one is a ...

13

This is a so-called "Pearson's square" or "Box method" of balancing ratios, originally used extensively in dairy industry (at least since 1920s judging from Google Books search). Earlier the similar approach has been used in sugar industry by using "Cobenz diagrams" aka spider diagrams. Widely popularized in Soviet books for analytical chemistry at least ...

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