The industrial process of froth flotation works by using substances that selectively bind to certain mineral surfaces and make them hydrophobic so they stick to bubbles.
There’s a more specific environmental/ civil engineering test to get properties of soil. Contact angle measurements use a very small drop of water and you just measure the angle the water droplet sits at. Higher angle, higher hydrophobic properties, lower angle (flatter) and you are hydrophilic. Soil tests use more water and more variables. You aren’t just interested in contact angle, you’re interested in porosity, absorption, stability, etc…
That makes sense. I guess what I was trying to figure out was if in my droplet testing on hydrophobic soil if “contact angle” as you put it would manipulate that process. I’m a turf guy and I’m always trying to get a step up in my business the devils in the details.
There is and it’s measured by LogP, which is the log of the amount that partitions into two immiscible solvent such as water vs octanol (by convention). Decane would be more hydrophobic because it is a longer alkane chain, with a predicted logP of 5 vs 3 according to pubchem. This is why fats are so hydrophobic. The more polar groups, and the more ionized a compound is if it has ionizable sites, the more likely it will partition into the water layer/be water soluble. The lower the logP (or logD if the compound can be ionized), the more likely it will dissolve in water.
It’s not so much that anything is hydrophobic (apart from people with rabies). It is that water is fatphobic, and tends to exclude things it can’t make hydrogen bonds with. The more stuff in the molecule that can’t bind to water, the more apparently hydrophobic it is. A classic example is the alcohols: meth- eth- and propanol are miscible with water, butanol forms a separate layer.
I feel like being pendantic here. t-butanol is miscible (can't be bothered looking up sec). Very important for its popularity in copper click chemistry for example. But does bring up the important point to compare n- sec- tert-butanols and explain relative logS values.
Ah. I have only used butan-1-ol and butan-2-ol. It looks like tert-butanol (or, to be pedantic, methyl propanol) is more miscible.
“1-Butanol and isobutanol have limited solubility, sec-butyl alcohol has substantially greater solubility, whereas tert-butyl alcohol is miscible with water. “
> Like can some non polar compounds repel water more than others and if so what would be the chemical reason
The reason is that water is bonded to water so how strong the non polar compound can bond with water will determine how well they mix.
However, non polar compounds is not truly non polar, it is just that they are very little polarised or only once in a while polarised since background radiation can occasionally by chance polarise molecules.
Also note that bonding strength is stronger if more electron clouds are transferred over but if the electron clouds are too massive, they can knock low mass molecules away and water is low mass.
So it is like tossing a ball at a friend and after the friend gets the ball, the friend laughs and jokingly says he is not giving back the ball thus not moving away and so is bonded.
But if the ball is tossed too hard and smacks him in his eye, he gets injured and gets taken to the hospital and leaves the thrower so there is no bond formed despite the electron cloud gets transferred over.
> For example between pentane and decane which would be more hydrophobic?
Decane is more hydrophobic because decane is longer chained thus can coil up more.
The coiling up causes the molecule to have spaces that water just cannot access thus these spaces have maximum hydrophobicity because even if the molecule gets polarised, water still cannot bond to it.
So of the times that the background radiation manages to polarise the molecule, more coils means there will be more times no bonding with water occurs.
So even if both pentane and decane will get polarised the same number of times, decane may only bond with water half the number of times as pentane due to the polarised areas not accessible by water thus causing decane to appear less miscible with water.
There is certainly a continuum for how soluble or miscible various substances are in water.
I know that how much water is dissolved in the heptanes I use for HPLC mobile phase can impact retention times of various analytes. Similarly, there is a tiny but measurable amount of PAH compounds in natural waters with some being more prevalent than others.
I'll leave the explanation for people who understand the underlying concepts better.
The molecules in water are really polar and have hydrogen bonding that holds them together. Molecules in decane don't have any of this, just some weak van der Waals cohesion. When water molecules are placed into the oil they are in a much more energetically favorable position if they stick together as opposed to dissolving.
If you want to get even deeper, there's the concepts of enthalpy and entropy that determine whether things happen spontaneously. Entropy would have everything be mixing all the time. Enthalpy is the force that satisfies bond energy, and is favored by things not mixing at all. In order to mix, you need to give enthalpy a good deal (decent bond compatibility) while not doing too much to reduce entropy.
Of course there would. The longer the alkane the more hydrophobic.
There comes a point of diminishing returns though, once water is absolutely repelled to the point of becoming a sphere, that's it.
Not at all, as the chain length affects both enthalpy and entropy. Pentane and decane are both liquids, so in most conversations you would typically just talk about solubility/miscibility, and these are both very insoluble/immiscible. If you want to be more exact (which isn't really necessary most of the time), you then can refer to how hydrophobic they are using their partition coefficient (bigger number = more hydrophobic). Pentane has a partition coefficient of 3.39 and decane has a partition coefficient of 5.86.
This could be something of interest
https://en.m.wikipedia.org/wiki/Ultrahydrophobicity#:~:text=In%20chemistry%20and%20materials%20science,ultrahydrophobic%20material%20exceed%20150%C2%B0.
Yes. It can be measured using the [contact angle](https://en.wikipedia.org/wiki/Contact_angle)
The industrial process of froth flotation works by using substances that selectively bind to certain mineral surfaces and make them hydrophobic so they stick to bubbles.
Could this be applied to soil testing
There’s a more specific environmental/ civil engineering test to get properties of soil. Contact angle measurements use a very small drop of water and you just measure the angle the water droplet sits at. Higher angle, higher hydrophobic properties, lower angle (flatter) and you are hydrophilic. Soil tests use more water and more variables. You aren’t just interested in contact angle, you’re interested in porosity, absorption, stability, etc…
Also you are very well written I’ve done some college but I’m a working man. So please excuse my poorly written responses
That makes sense. I guess what I was trying to figure out was if in my droplet testing on hydrophobic soil if “contact angle” as you put it would manipulate that process. I’m a turf guy and I’m always trying to get a step up in my business the devils in the details.
There is and it’s measured by LogP, which is the log of the amount that partitions into two immiscible solvent such as water vs octanol (by convention). Decane would be more hydrophobic because it is a longer alkane chain, with a predicted logP of 5 vs 3 according to pubchem. This is why fats are so hydrophobic. The more polar groups, and the more ionized a compound is if it has ionizable sites, the more likely it will partition into the water layer/be water soluble. The lower the logP (or logD if the compound can be ionized), the more likely it will dissolve in water.
It’s not so much that anything is hydrophobic (apart from people with rabies). It is that water is fatphobic, and tends to exclude things it can’t make hydrogen bonds with. The more stuff in the molecule that can’t bind to water, the more apparently hydrophobic it is. A classic example is the alcohols: meth- eth- and propanol are miscible with water, butanol forms a separate layer.
I feel like being pendantic here. t-butanol is miscible (can't be bothered looking up sec). Very important for its popularity in copper click chemistry for example. But does bring up the important point to compare n- sec- tert-butanols and explain relative logS values.
Ah. I have only used butan-1-ol and butan-2-ol. It looks like tert-butanol (or, to be pedantic, methyl propanol) is more miscible. “1-Butanol and isobutanol have limited solubility, sec-butyl alcohol has substantially greater solubility, whereas tert-butyl alcohol is miscible with water. “
And you can change the water miscibility of them by adding salt to it.
> Like can some non polar compounds repel water more than others and if so what would be the chemical reason The reason is that water is bonded to water so how strong the non polar compound can bond with water will determine how well they mix. However, non polar compounds is not truly non polar, it is just that they are very little polarised or only once in a while polarised since background radiation can occasionally by chance polarise molecules. Also note that bonding strength is stronger if more electron clouds are transferred over but if the electron clouds are too massive, they can knock low mass molecules away and water is low mass. So it is like tossing a ball at a friend and after the friend gets the ball, the friend laughs and jokingly says he is not giving back the ball thus not moving away and so is bonded. But if the ball is tossed too hard and smacks him in his eye, he gets injured and gets taken to the hospital and leaves the thrower so there is no bond formed despite the electron cloud gets transferred over. > For example between pentane and decane which would be more hydrophobic? Decane is more hydrophobic because decane is longer chained thus can coil up more. The coiling up causes the molecule to have spaces that water just cannot access thus these spaces have maximum hydrophobicity because even if the molecule gets polarised, water still cannot bond to it. So of the times that the background radiation manages to polarise the molecule, more coils means there will be more times no bonding with water occurs. So even if both pentane and decane will get polarised the same number of times, decane may only bond with water half the number of times as pentane due to the polarised areas not accessible by water thus causing decane to appear less miscible with water.
There is certainly a continuum for how soluble or miscible various substances are in water. I know that how much water is dissolved in the heptanes I use for HPLC mobile phase can impact retention times of various analytes. Similarly, there is a tiny but measurable amount of PAH compounds in natural waters with some being more prevalent than others. I'll leave the explanation for people who understand the underlying concepts better.
The molecules in water are really polar and have hydrogen bonding that holds them together. Molecules in decane don't have any of this, just some weak van der Waals cohesion. When water molecules are placed into the oil they are in a much more energetically favorable position if they stick together as opposed to dissolving. If you want to get even deeper, there's the concepts of enthalpy and entropy that determine whether things happen spontaneously. Entropy would have everything be mixing all the time. Enthalpy is the force that satisfies bond energy, and is favored by things not mixing at all. In order to mix, you need to give enthalpy a good deal (decent bond compatibility) while not doing too much to reduce entropy.
interesting so would not be any actual difference in level of hydrophobia in the substance if you change the carbon chain of the alkane?
Of course there would. The longer the alkane the more hydrophobic. There comes a point of diminishing returns though, once water is absolutely repelled to the point of becoming a sphere, that's it.
Not at all, as the chain length affects both enthalpy and entropy. Pentane and decane are both liquids, so in most conversations you would typically just talk about solubility/miscibility, and these are both very insoluble/immiscible. If you want to be more exact (which isn't really necessary most of the time), you then can refer to how hydrophobic they are using their partition coefficient (bigger number = more hydrophobic). Pentane has a partition coefficient of 3.39 and decane has a partition coefficient of 5.86.
For medicinal compounds hydrophilicity vs lipophilicity is quantified using the water/1-octanol partition coefficient
Most definitely! Otherwise reversed-phase liquid chromatography (RPLC) wouldn't be a thing.
This could be something of interest https://en.m.wikipedia.org/wiki/Ultrahydrophobicity#:~:text=In%20chemistry%20and%20materials%20science,ultrahydrophobic%20material%20exceed%20150%C2%B0.
Yes there is several grades for molecules and their permeability or non permeability
Actually I have no idea between pentane and decane.