why the boiling point of tertiary butyl alcohol is lower than normal alcohol?
822453
The boiling point series for short alcohols is dominated by hydrogen bonding.  That's where the H on the hydroxyl group (OH)  on one molecule is attracted to the O on a nearby molecule.\nEven tough "normal alcohol" (I imagine you mean n-butanol from the context of your question) is just as heavy, it will have a higher boiling point because its structure makes hydrogen bonding easier.  It is basically alike to a bunch of strings with the magnets on their ends with nothing to impede the other strings from glomming on.\nTert-butanol, on the other hand, is like a bunch of knotted strings with magnets at the base of the knot.  The hydroxyl group on these molecules are not all that available for their neighboring molecules to find and be attracted to.  This is called "steric hinderance" and is more a physical and spatial consideration than a chemical phenomenon.
229195
When you add a salt to water and the container feels cold, yes, an endothermic reaction is taking place.  The solution is grabbing heat from the surroundings to get the salt to dissolve.  When you add a salt to a pure solvent (say, water), the freezing point will go down and the boiling point will go up.  That's because the vapor pressure of the pure solvent is lowered (this would be easier to explain with a phase diagram).  Remember, the definition of BP is the temp at which the solution's vapor pressure equals the external pressure.  By lowering the vapor pressure, the whole phase diagram shifts...BP to the right (higher), FP to the left (lower).  You may want to check out a intro level chemistry text or at least draw out the phase diagram to see more clearly what gets lost is just words here.  Did you ever try boiling water without heating it?  If you have the means, hook up a vacuum to a flask of water.  You don't change the vapor pressure of the water, but you reduce the external pressure enough so that the water does boil.\n\nOne more thing...  The change in BP and FP is related to how much salt is added to the solvent:  delta T (change in T) = Km  where K is either what's called the molal freezing-point depression constant or molal boiling-point elevation constant;  m is the molality of the solution defined as moles of solute (salt) / kilograms of solvent. By knowing the constant for the solvent, how much solvent you have and how much solute you add, you can predict by how much (in degrees (C) the BP or FP will change.\n\nI would just like to add a couple of more comments... The reaction that is endothermic in this case is  NaCl(s) --> Na+(aq) + Cl-(aq)  ...  The reason that the freezing point is lowered is as J. Schultz said - the vapor pressure is lowered ....  However there is a simple analogy (that may be useful) which gives a simplified picture ... Freezing involves the water molecules becoming very ordered in crystalline lattice...  However when there are foreign particles such as Na+ and Cl- ions in the water they hinder the formation of the crystalline structure because they interfere with the intermolecular forces between the water molecules.  Also, the freezing point depression and boiling point elevation are called colligative properties...  that is, they are properties that depend only on the number of solute particles and not on their chemical properties...  The third famous colligative property is osmotic pressure.
799054
Consider a primary alcohol that has a structure like C--OH\n\nthen consider a tertiary alcohol that has a structure similar to \n          CH3\n           |\nH3C--C--OH\n           |\n          CH3\n\nIn a primary alcohol such as the one shown above, the distribution of charge is relatively polar due to the presence of only one other carbon atom with one very electronegative oxygen atom. In a tertiary alcohol, there are four carbon atoms versus only one electronegative oxygen atom. Therefore, in the tertiary carbon, the polarity is greatly less because the polarity is balanced by the presence of so many carbon atoms around the molecule.
1162703
Higher. Boiling point is reached when the vapour pressure of the liquid is equal to the outside pressure. At sea -level boiling point of water is 100 C. So below sea level, since the air pressure is greater, boiling point is higher than 100 C
837121
Hmmm.. The one affecting the boiling point is the intermolecular force..\nAs you can see, most of the compound here is polar. \n\nTherefore all you have to do is if the compound is consisted only of 2 elements (Group 17), you'll have to calculate the electronegativity difference. The more difference between them, the boiling will increase as well.\n\nIf there is more than 2 atoms in a molecule, you'll have to see the dipole moment magnitude (a.k.a polarity). The higher the magnitude, the higher the boiling point will be.\n\n\npeace\nvixklen
791892
this question may appear ambiguous to the inexperienced. the question asks for an explanation for the decrease, which implies the asker's initial expectation for an increase. the questioner assumed that viscosity increased with ethanol concentration, but facts led to the conclusion that this trend is only obeyed up to the 40% conc level, after which viscosity decreases with ethanol concentration.\n\nwhy the bell curve? that is what you are supposed to answer, Radagast.\n\n40% ethanol (w/w in water, which is the obvious solvent) happens to be the point at which there is a certain ratio of ethanol to water molecules. this special ratio is apparently the point at which there are maximum interactions (H-bonding) between ethanol and water such that the fluid becomes more viscous than water or ethanol alone.\n\nby increasing ethanol conc from 0-40% you will thus see an increase in viscosity. after 40%, the ratio of water molecules apparently increases, so the fluid viscosity will tend toward the viscosity of ethanol (which is still higher than pure water).\n\nusing arbitrary values, viscosity starts at 1 for pure water, increases to 10 for 40% ethanol, then decreases to 2 for 100% ethanol.
355097
Simply it will raise the boiling point and lower the freazing point.  Unless the solute is a liquid with a boiling point bellow that of water when the boiling point will go down.\n\nMore complecatedly. When something disolves in water its molecules bind to the molecules of water creating a solvation shell (a group of water mollecules that move with the solute) for the water to boil you need to strip these molicules away from the solute which takes energy and hence the  boiling point goes up. For a liquid with a lower boiling point than water the molecules of the solute will be lost first (but above its boiling point) and some water will go with them (distilation of alcohol being the classic example). \n\nFor water to freaze the water molecules must bind to each other to form crystals of ice which creates order and gives out energy. If a substance is disolved in the water then again you must break the bonds between the solute and the water to do this. This means you get less energy from forming the water-water bonds in the crystal as you have used it to break the water-solute bond. Now if a process is to create order within a system (the solution) it must make more disorder elsewhere (the rest of the world). This is called the second law of thermodynamics (the law is stated diffrently but this is one consequence of it). So if the energy we given out when the water freazes is reduced so is the amount of disorder it creates. However as the temp goes down the amount of order we create is reduced as the molecules of water move more slowly and so are more "ordered" to start with. So when the amount of order we create is equal to the amount of disorder the energy relased by freazing will produce the water freazes. So as the amount of energy relased is reduced so the tempreature when this is true becomes lower.
15822
It mainly depends on the pressure (if we are talking about pure water). The higher the pressure, the higher the boiling point - it can be much lower (ex. high in the mountains) or much higher than 100 degrees C (the boiling point under normal atmospheric pressure). If we don't talk about pure water, then adding other chemicals (for example, table salt - sodium chloride) can raise the boiling point as well.
417679
alcohols have a hydroxyl group, which the oxygen atom is electronegative and induces polarisation to the O-H bond, that means the oxygen atom is negatively changed and the hydrogen atom is positively charged (in the hydroxyl group). So that hydrogen atom in the hydroxyl group attracts to other negatively charged oxygen atoms on another molecule, so the 2 are held together by what is called hydrogen bonding\n\nalkane molecules only hold on together by Van der Waals forces, which is weak, whereas alcohols hold on together by hydrogen bonding and Van der Waals forces, which is a lot stronger\n\nso with stronger intermolecular forces, molecules hold on to each other stronger and therefore results as a higher boiling and melting point
472294
As a general rule boiling point of substances increase with increase in pressure.\n\nAlkanes of smaller no. of carbon atoms are gases at NTP but if pressure is increased the alkanes will convert to liquids.\n\nAll isomers of Butane (4 C atoms) and Propane (3 C atoms) will easily convert to liquids at high pressure.\nThe role of temperature in converting gases to liquids will be of prime importance.\n\nHigh alkanes under high pressure will gradually become more and more viscuss.
526842
The total vapor pressure of the solution is equal to the sum of the two partial pressures of the components of the solution.\n\nUsing the mole fraction of the solution, find the conbination of methanol and propanol which will give you the desired vapor pressure.\n\npartial pressure of methanol  = vapor pressure of methanol  * mole fraction of methanol\npartial pressure of propanol = Mole fraction of propanol * vapor pressure of propanol\n\npartial pressure of propanol + partial pressure of methanol = total solution vapor pressure
423892
I'm sure that's what you're supposed to determine in the lab you're working on. Good luck.\n\nI've been able to find a value for the heat capacity of n-hexadecanol (cetyl alcohol) in my copy of _Lange's Handbook of Chemistry, 13th Edition_.  When you've come up with your value from the experiment, post it here and I'll check to see if you're close.
874660
This is sort of a guess, so you may wish to verify it for sure.  I know, for sure alcohol, has a much lower freezing point.  So if you put cells in a 50% alcohol solution, the cells would require a lower temperature for freezing.  \n\nYour question is not about freezing cells Per Se, so maybe this extra tidbit will be more helpful:  \n\nI have put cells in 70% alcohol solution and maintained them in a freezer.  I did this because I wanted to preserve the antigens present on the cell membrane.  I believe you would have to do this for an hour or so, in order for best preservation.  But you would probably need to use the cells in the follow-up assay (for me it was flow cytometry) within a 24 hour period.\n\nWhen I have deep freezed cells for long term storage, I did it in DMSO.  That's the standard method.\n\nIn short, keeping cells in 70% ethanol will preserve antigen found on cell surface membrane.\n\nI wish I could speak for chloroform, but nowadays people rarely use it due to its high toxicity and high flash point. \n\nHope this helps.
789425
I think it has to do with the fact that there is a benzene ring on it. The pKa of benzene is around 7 or 8, I believe. So benzene could have a n affect on the level of its acidity. \n\nIt could possibly be harder for a base to pick up a proton off the alcohol on the phenol than on the alcohol on a regular carbon chain, or ring with no double bonds. \n\nbut I'm just guessing.
780518
I'm using the Lewis classification of acids and bases, okay? It's pretty much all that works in this case. I'll try to keep it simple.\n\nIt's more acidic than water because water is neutral (it can't accept any more electrons).\n\nIt's more acidic than other alcohols because the carbon chain is the shortest here. The longer the carbon chain is, the more electrons there are, so the chance of another electron being attracted to the molecule is pretty slim. Since there's only one carbon in methanol, the electronegativity of the oxygen atom prevails and attracts electrons to itself.\n\nI hope that was clear enough. Good luck!
185785
In short chain alchohols the hydrogen bonding is more extensive and in long chain it is less {because of steric hinderance}.Now, when you add alchohols to water ,the already existing h-bonding in water is broken.Now,the short chain alchohols can form h -bonds with water compensating for the broken ones and hence can remain in solution and hence are more soluble.The long chain ones form less amount of h-bonding with water and hence are less soluble .\n\nh-bonding are favourable interactions for forming solutions taking entropy conditions \n\nhope this answered your question
285773
A still works by taking advantage of the different boiling points for various liquids. For instance, alcohol boils at a lower temperature than water; therefore, you can heat a mixture of alcohol and water and the alcohol will tend to boil first. If you then condense the alcohol vapors, you have made a separation.\n\nThis is an over simplification because even with the alcohol as it vaporizes, some of the water also vaporizes. To make a purer product, you must repeat the process many times. A special column called a fractional distillation column permits you to make a nearly perfect separation