This lab is about Sublimation and specifically purification of Camphor by Sublim

Question

This lab is about Sublimation and specifically purification of Camphor by Sublimation. The questions are as follows:

1. Why was a filter flask used instead of an Erlenmeyer flask?

2. Why was the ice-water removed from the cold finger before lifting the colf finger out of the filter flask?

3. Why were the melting-point capillary tubes sealed before the melting points were determined?

4. An organic compound has a melting-point range of 156-157 degrees Celsius. Its vapor pressure at that temperature range is 231 mm. how can it be sublimed?

Thank you so so much!!!

Explanation / Answer

1)the reason for the shape of an Erlenmeyer flask is that any liquid that is splashed up on the sides of the flask will run down the angled walls of the flask back into the solution in the bottom. The angled walls are more efficient at this that the vertical walls of a beaker.

In addition, the shape of an Erlenmeyer flask makes it easier to pick up drops that don't run down the sides. This is handy for "splitting drops" of added titrant.

2)Ha. I've got the same problem as you only it's on the left.
Don't use heat.....try a cold compress instead. This is the only thing working for me right now in addition to a warm shower after the ice and tons of Advil.

As for sleeping....I've been sleeping on my back, or at least trying to without my pillow. To get up in the morning, do the log roll. Roll your legs out first, then your torso...I end up standing on the floor with my head resting on the bed and then slowly rise trying to keep my head aligned with my back. SO much easier than trying to sit upright and then getting out.

3)

the melting-point capillary tubes sealed before the melting points were determined because it dont interfere in measurment

4)This is a great chemistry question. I hope you are interested in studying chemistry!First sugar melts at 146 degrees Celsius (or about 295 degrees Fahrenheit). I hope you are really thinking of melting point and not of sugar dissolving into a liquid, like water, or like putting it on your tongue and it "melts" away. This isn't melting, this is dissolving. These are two different things.When something dissolves it really is making a mixture of two substances that is the same throughout the mixture (a homogenous mixture). Sugar dissolves in water to make a homogenous solution. Sugar dissolves on the tongue in saliva (which has a lot of water in it) to make another type of homogenous solution.Melting point is the change of a substance from its solid state to its liquid state. In order to "melt" something enough energy (heat) has to be put into the substance in order for the attraction(s) between different molecules to be overcome. These attractions are called intermolecular forces and there are a few different types of them. The strongest intermolecular force between sugar molecules is known as hydrogen bonding. It is the strongest of all intermolecular forces. So this phenomenon has a tendency to increase a substances' melting point.Another factor is the overall type of solid it is: there generally are 3 types of crystalline solids (sugar is a crystalline solid) - atomic, ionic, and molecular. Atomic solids are things like sodium metal, pure carbon, and things like that. Atomic solids have melting points all over the place. Hydrogen for instance has a melting point of about -269 degrees centigrade (Celsius).Ionic solids are things like table salt, sodium chloride. Ionic solids tend to have higher melting points than other things.Molecular solids, sugar is one, tend to have lower melting points. Of course when we say lower, it is all relative. If you look at a series of similar solids they usually will have a definite trend in melting points within the series. The trend depends on lots of things.Sugar's melting point isn't really all that low, it depends on what you are comparing it to. Compared to something like elemental hydrogen, it is pretty high. Compared to the melting point of something like chromium it is pretty low. Chromium is an atomic solid that melts at 1,857 degrees C. (or about 3,375 degrees F.)

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.