miércoles, 30 de octubre de 2013

This table represents the data we obtained from the experiment:




Why do ionic compounds dissolve in water?
The H2O and the ionic compounds have oppositely charged ions so they are attracted between them. Another reason why they dissolve in water is that H2Ois a polar compound and ionic compounds are attracted to it.

Why do covalent compounds dissolve in acetone(a covalent compound)?
Covalent compounds dissolve in other covalent compounds because they share the same properties, especially polarity. When a covalent compound is polar, it will be soluble in acetone because acetone is a polar covalent compound. The solution occurs as a result of hydrogen bonding between the compounds.


Why do metals conduct electricity?
The outer electrons of metal atoms are not tied to any atom, they are valence electrons. When electrical current is applied, the electrons can move freely to conduct electricity.


Why do covalent compounds NOT conduct electricity?
The reason why this happens is because in covalent compounds there are no ions, this means that they haven’t got an electrical charge (positive or negative) through which the electricity can’t pass through.


Why do ionic compounds have such high boiling points?Why do metals have such high boiling points?
Ionic compounds form very strong bonds, and the energy required to break these bonds is much higher than seen in most other bonds. The energy required for an ionic solid to melt (temperature at melting point) is therefore high, and even higher for the boiling point of course.







Schlenk Tube


Introduction:

A Schlenk tube is a reaction vessel typically usedd in air sensitive chemistry. It was an invention of Wilhelm Schlenk. These tubes are made of borosilicate glass such as Pyrex.
There a several types of Schlenk tubes;

  • Schlenk flasks are round bottomed
  • Schlenk tubes are elongated 
Schlenk tubes are used to work out the pressure of gases. Also by connecting the Schlenk tube to Schlenk Schlenk lines we can fill and evacuate the tube or flask with gases like nitrogen or argon.

Method step by step:

  1. Make the rubber band double (fold it)
  2. Put it through the bottom and stretch
  3. Pass the rubber band throught the top
  4. Twist the rubber band before repeating the last step. Repeat the last step.
  5. Repeat step 4.
  6. After having put the rubber band through the top of the Schlenk tube, stretch and pass it to the bottom of the tube. (the fianl result should look simetrical)

miércoles, 9 de octubre de 2013

This is a blog to learn how to make a Schlenk tube made by Alejandro Fito, Elisa Hidalgo e Isabel Aceituno