Monday, April 19, 2010
Global warming awareness
The earth is sick.Why?We only have ourselves to blame. Human activities have destroyed our planet. The burning of coal, oil and fuels have created so much greenhouse gases the average temperature of the earth has increased drastically. There are many causes to greenhousw gases. Wasting electricity at home contributes to global warming. Whenever we waste electricity,more fuel has to be burned to supply electricity to the appliances. The releases unwanted greenhouse gases. Some other causes are areosol sprays that contain chlorofluorocarbons or CFC which destroys the ozone layer, allowing the radiative rays of the sun to harm us and also heating the earth. Deforestation also contribute a lot as when the people burn down the forest to build buildings, carbon dioxide is produced and it will rise up into the atmosphere and it will trap the heat in the earth, heating it up. To conclude, global warming can affect our lives very much just that we do not feel it now yet so let us save the earth before it is too late.
Why does fire create smoke
If you now toss a piece of wood, or even a sheet of paper, onto this fire, what you will notice is that the new fuel produces a lot of smoke as it heats up. Then, all of a sudden (often with a small pop), it bursts into flame and the smoke disappears. There are four things that you find in any piece of wood:
1.Water - Freshly cut wood contains a lot of water (sometimes more than half of its weight is water). Seasoned wood (wood that has been allowed to sit for a year or two) or kiln-dried wood contains a lot less water, but it still contains some.
2.Volatile organic compounds - When the tree was alive, it contained sap and a wide variety of volatile hydrocarbons in its cells. If you have read How Food Works, you know that cellulose (a chief component of wood) is a carbohydrate, meaning it is made of glucose. A compound is "volatile" if it evaporates when heated. These compounds are all combustible (gasoline and alcohol are, after all, hydrocarbons -- the volatile hydrocarbons in wood burn the same way).
3.Carbon
4.Ash - Ash is the non-burnable minerals in the tree's cells, like calcium, potassium and magnesium.
When you put the fresh piece of wood or paper on a hot fire, the smoke you see is those volatile hydrocarbons evaporating from the wood. They start vaporizing at high temperatures. If the temperature gets high enough, these compounds burst into flame. Once they start burning, there is no smoke because the hydrocarbons are turned into carbon dioxide and water (both invisible) when they burn.
This explains why you see no smoke from a charcoal fire (or a fire that has burned down to embers). Charcoal is created by heating wood to high temperatures in the absence of oxygen.
1.Water - Freshly cut wood contains a lot of water (sometimes more than half of its weight is water). Seasoned wood (wood that has been allowed to sit for a year or two) or kiln-dried wood contains a lot less water, but it still contains some.
2.Volatile organic compounds - When the tree was alive, it contained sap and a wide variety of volatile hydrocarbons in its cells. If you have read How Food Works, you know that cellulose (a chief component of wood) is a carbohydrate, meaning it is made of glucose. A compound is "volatile" if it evaporates when heated. These compounds are all combustible (gasoline and alcohol are, after all, hydrocarbons -- the volatile hydrocarbons in wood burn the same way).
3.Carbon
4.Ash - Ash is the non-burnable minerals in the tree's cells, like calcium, potassium and magnesium.
When you put the fresh piece of wood or paper on a hot fire, the smoke you see is those volatile hydrocarbons evaporating from the wood. They start vaporizing at high temperatures. If the temperature gets high enough, these compounds burst into flame. Once they start burning, there is no smoke because the hydrocarbons are turned into carbon dioxide and water (both invisible) when they burn.
This explains why you see no smoke from a charcoal fire (or a fire that has burned down to embers). Charcoal is created by heating wood to high temperatures in the absence of oxygen.
Diamond vs Graphite
Diamond and Graphite, the most interesting elements. How are they similar?They are both carbons, just of different crystal structures are called polymorphs. Another important physical difference is their hardness. The hardness of minerals is compared using the Mohs Hardness Scale, a relative scale numbered 1 (softest) to 10 (hardest). Graphite is very soft and has a hardness of 1 to 2 on this scale. Diamonds are the hardest known natural substance and have a hardness of 10. No other naturally occurring substance has a hardness of 10. The crystal structure of graphite yields physical properties that permit the use of graphite as a lubricant and as pencil lead. The gem and industrial properties of diamond, physical properties that we cherish and exploit, are also a result of diamond's crystal structure.
Conclusion:
Diamonds and graphites are both carbons, just of different polymorphs, or structures of the atoms.
Conclusion:
Diamonds and graphites are both carbons, just of different polymorphs, or structures of the atoms.
Why does ice float on water?
Have you ever wondered why does ice float on water?
A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way, or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.
Water reaches its maximum density at 4°C . As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid state than in their liquid state.
Why?
I found out that water is different because of hydrogen bonding.A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.
Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a litre of ice weighs less than a litre water. The heavier water displaces the lighter ice, so ice floats to the top.
If water floats on ice,that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.
A substance floats if it is less dense, or has less mass per unit volume, than other components in a mixture. For example, if you toss a handful of rocks into a bucket of water, the rocks, which are dense compared to the water, will sink. The water, which is less dense than the rocks, will float. Basically, the rocks push the water out of the way, or displace it. For an object to be able to float, it has to displace a weight of fluid equal to its own weight.
Water reaches its maximum density at 4°C . As it cools further and freezes into ice, it actually becomes less dense. On the other hand, most substances are most dense in their solid state than in their liquid state.
Why?
I found out that water is different because of hydrogen bonding.A water molecule is made from one oxygen atom and two hydrogen atoms, strongly joined to each other with covalent bonds. Water molecules are also attracted to each other by weaker chemical bonds (hydrogen bonds) between the positively-charged hydrogen atoms and the negatively-charged oxygen atoms of neighboring water molecules. As water cools below 4°C, the hydrogen bonds adjust to hold the negatively charged oxygen atoms apart. This produces a crystal lattice, which is commonly known as 'ice'.
Ice floats because it is about 9% less dense than liquid water. In other words, ice takes up about 9% more space than water, so a litre of ice weighs less than a litre water. The heavier water displaces the lighter ice, so ice floats to the top.
If water floats on ice,that lakes and rivers freeze from top to bottom, allowing fish to survive even when the surface of a lake has frozen over. If ice sank, the water would be displaced to the top and exposed to the colder temperature, forcing rivers and lakes to fill with ice and freeze solid.
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