An alkali is a type of base that is soluble in water, to produce the OH- ion. They have a pH of more than 7, have a bitter taste and feel soapy. They turn the universal indicator blue or violet, depending on the pH level, and turn red litmus blue.
As usual, I got some interesting facts about alkalis off the Internet:
- Caesium and rubidium are used to make atomic clocks. Caesium clocks are known to be the most accurate clock to date.
- Different alkalis burn with different coloured flames (which we already know), including sodium (orange yellow), lithium (red), potassium (lilac), rubidium (red), and caesium (blue or violet)
- All the alkalis metals have odd atomic numbers.
- Alkali is derived from the Arabic word for "ashes".
Source: http://www.ducksters.com/science/chemistry/alkali_metals.php
Many of these have probably been discussed before, but they are still very interesting.
Sunday, 11 May 2014
Acids and Bases
Everyone knows that an acid produces H+ ions in water. That they react with reactive metal to form salt and hydrogen gas. Acids have a pH of less than 7, tun litmus paper red, and turn the universal indicator either red or yellow, depending on the pH level. A base is a metal oxide or hydroxide that reacts with an acid to produce salt and water only.
Well, once again, I got curious, so I went to find out about the strongest acid yet. Made in California (in a lab), the carborane acid is the first 'superacid' that can be stored in a bottle, unlike the others, which are so corrosive that it wuld eat straight through the glass. This is due to the fact that even though it is a million times more potent that the concentrated sulfuric acid, it is one of the least corrosive acids.
Resource:
http://www.nature.com/news/2004/041115/full/news041115-5.html
Well, once again, I got curious, so I went to find out about the strongest acid yet. Made in California (in a lab), the carborane acid is the first 'superacid' that can be stored in a bottle, unlike the others, which are so corrosive that it wuld eat straight through the glass. This is due to the fact that even though it is a million times more potent that the concentrated sulfuric acid, it is one of the least corrosive acids.
Resource:
http://www.nature.com/news/2004/041115/full/news041115-5.html
Saturday, 10 May 2014
Crystallisation (Practical)
Again, another small practical that teaches us the most common method used to purify soluble liquids. And this time, the result wasn't even as satisfying.
At Step 3 and 4, Ruth and I did not fully dissolve all the copper(II) sulfate when we stopped.
Also, at Step 7, where we had to stop heating when about half the solvent had evaporated, we did not do an absolutely good job. When we switched off the bunsen burner, there was still a lot of the solvent remaining, yet to be evaporated.
In the end, we managed to come up with a couple of medium-sized crystals, and the remaining were very small and powdery.
After doing research on the Internet, I found some interesting fun facts about crystals, even though they have nothing to do with the process of crystallisation.
The oldest known crystals on earth are zircon crystals on the Jack Hills of Western Australia, which are around 4.4 billion years old, and in Chihuahua Desert, the largest natural crystal:translucent beams of gypsum as long as 36 feet and softer than human nails. The cave that it is in is known as the Cueva de los Cristales (Cave of Crystals) and have a warm temperature of 58ºC due to a magma chamber about 2.5km away that flows through the mountain, as it is on a set of fault lines (hehe Geography).
Finally, many experts believe that the center of earth is a 2414km wide iron crystal, although it may not be a single solid crystal, but a compound of smaller crystals.
Links:
http://www.myinterestingfacts.com/crystal-facts/
http://www.telegraph.co.uk/news/newstopics/howaboutthat/3269047/Worlds-largest-crystal-discovered-in-Mexican-cave.html
At Step 3 and 4, Ruth and I did not fully dissolve all the copper(II) sulfate when we stopped.
Also, at Step 7, where we had to stop heating when about half the solvent had evaporated, we did not do an absolutely good job. When we switched off the bunsen burner, there was still a lot of the solvent remaining, yet to be evaporated.
In the end, we managed to come up with a couple of medium-sized crystals, and the remaining were very small and powdery.
After doing research on the Internet, I found some interesting fun facts about crystals, even though they have nothing to do with the process of crystallisation.
The oldest known crystals on earth are zircon crystals on the Jack Hills of Western Australia, which are around 4.4 billion years old, and in Chihuahua Desert, the largest natural crystal:translucent beams of gypsum as long as 36 feet and softer than human nails. The cave that it is in is known as the Cueva de los Cristales (Cave of Crystals) and have a warm temperature of 58ºC due to a magma chamber about 2.5km away that flows through the mountain, as it is on a set of fault lines (hehe Geography).
Finally, many experts believe that the center of earth is a 2414km wide iron crystal, although it may not be a single solid crystal, but a compound of smaller crystals.
Links:
http://www.myinterestingfacts.com/crystal-facts/
http://www.telegraph.co.uk/news/newstopics/howaboutthat/3269047/Worlds-largest-crystal-discovered-in-Mexican-cave.html
Paper Chromatography (Practical)
Until now, I still can't resist the thought of dropping all my unwanted worksheets into water, even though I know that's not how it is supposed to be done.
The practical was a very simple and straightforward practical, and it only took a couple of minutes at most, but it is one of the most memorable experiments I had in the chemistry module.
I always like colour combinations, but to think that a blue pen would contain so much red and yellow colours still sets me thinking.
The practical was a very simple and straightforward practical, and it only took a couple of minutes at most, but it is one of the most memorable experiments I had in the chemistry module.
I always like colour combinations, but to think that a blue pen would contain so much red and yellow colours still sets me thinking.
| Component | Distance moved by spot/cm |
Distance moved by solvent/cm |
Rf |
|---|---|---|---|
| Yellow | 5.0 | 10 | 0.50 |
| Red | 1.0 | 10 | 0.10 |
| Purple | 0.5 | 10 | 0.05 |
| Blue | 1.0 | 10 | 1.00 |
After doing more research, I found out that there were different types of paper chromatography, including:
1) Ascending Paper Chromatography
2) Descending Paper Chromatography
3) Ascending-Descending Paper Chromatography
4) Horizontal Paper Chromatography
5) Two-Dimensional Paper Chromatography
Also, I found out that there is also a different type of paper chromatography, known as Thin-Layer Chromatography.
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