In this lesson, we learn about Photosynthesis and respiration.
Photosynthesis takes place in the presence of carbon dioxide, water, light and chlorophyll. It is the process which plants do to produce food. Photosynthesis also removes carbon dioxide and provides oxygen.
Aerobic respiration is the process by which glucose and oxygen are broken down into carbon dioxide, water and energy.It is a bit like the reverse of photosynthesis
Friday, September 10, 2010
The magnesium ribbon
In this lesson, we did an experiment on compound. We were told to place the magnesium ribbon over the flame and see what happen next. Yue Heng and i broke the magnesium ribbon into two as we both wanted to try. When the magnesium ribbon was placed over the flame, it glowed so brightly that it could blind us. No wonder the worksheet told us not to stare at it.......
We also discussed about compounds in class. We were also taught how to write a word equation.
We also discussed about compounds in class. We were also taught how to write a word equation.
Tuesday, September 7, 2010
Elements, Compounds and Mixtures!!
This was the coolest experiment that i tried in my whole life!!!!
We were to find out the properties between a mixture and a compound. We learnt that sulpher and iron will become a mixture when mixed and when heated, a compound is formed. Sulfer is yellowish and powderish. We also found out that it could not be attracted to the magnet. After that we observed some iron fillings and found out that it was black, needle-like and that it ATTRACTED to the magnet. Next, we mixed the both items together and formed a mixture. It was yellowish and black and still powderish. Then we heated the two items together and formed a compound. The mixture melts and formed a black solid. The compound could not be attracted to the magnet. T.T! Then we discussed about some facts about the compound and mixture with our Science Teacher, Ms Leong and found out that the heat had distroyed some of the properties. Then we moved on to naming some new elements.
We were to find out the properties between a mixture and a compound. We learnt that sulpher and iron will become a mixture when mixed and when heated, a compound is formed. Sulfer is yellowish and powderish. We also found out that it could not be attracted to the magnet. After that we observed some iron fillings and found out that it was black, needle-like and that it ATTRACTED to the magnet. Next, we mixed the both items together and formed a mixture. It was yellowish and black and still powderish. Then we heated the two items together and formed a compound. The mixture melts and formed a black solid. The compound could not be attracted to the magnet. T.T! Then we discussed about some facts about the compound and mixture with our Science Teacher, Ms Leong and found out that the heat had distroyed some of the properties. Then we moved on to naming some new elements.
Monday, September 6, 2010
Science Ace 2!!!
This was my second Ace project!!
Name: Tan Jin Neng, Clarence
Class: 1A3 (28)
Term 3 Science Ace
Experiment on obtaining water from salt water
Introduction:
Mixtures are not chemically joined and we can use physical methods to obtain the components of the mixture. The various separation techniques are Filtering, Chromatography, Distillation, Fractional Distillation and Evaporation.
A solution is a mixture. It is formed when a solid, a liquid or a gas dissolves in a liquid. For example, if you stir salt into water, the salt dissolves. It breaks up into individual salt molecules. The solution is now a mixture of water molecules and salt molecules. The salt is called the solute and the water is called the solvent.
Experiment set up:
As we have learnt that we can obtain a solvent from a solution using distillation, I shall do an experiment on distillation to obtain water from salt solution, not in the laboratory but at home. Since it is at home, I do not have the necessary laboratory apparatus like flask, Bunsen burner, condenser, etc, I shall make use of some kitchen utensils.
These are the things that I am going to use for the experiment: A cup of water, some salt (sodium chloride), an empty saucer, cooking pot, aluminum foil, ice cubes and a spoon.
First, I shall dissolve some salt into the water. Stir it until the salt dissolves.
Next I pour the salt solution into the cooking pot.
Place the pot onto a stove. Place the empty saucer in the cooking pot. Cover the pot with an aluminum foil and put some ice cubes on the foil.
Heat the salt solution until all the ice cubes have melted.
Remove the aluminum foil and take out the saucer from the cooking pot.
Some water is collected in the saucer. We can further test if the water is pure by boiling it. If it boils at 100°C, it means the water is pure.
Conclusion:
The melting and boiling points of salt and water are tabulated below:
Salt Water
Boiling point 1413°C 100°C
Melting point 801°C 0°C
As water has a lower boiling point than salt, 100°C (water) compared to 1413°C (salt), water evaporates first when the salt solution is heated. Water vapour condenses to form water droplets when in contact with a cool surface which is the aluminum foil with ice cubes on it. As the weight of the ice cubes form a depression on the centre of the aluminum foil, the water droplets then drip into the saucer. The salt will not evaporate yet as its boiling point is 1413°C and therefore is left in the pot.
These are the link to my videos as i cannot upload them ):
http://www.youtube.com/watch?v=xPICTyqui40
http://www.youtube.com/watch?v=eeipv9xCdtM
http://www.youtube.com/watch?v=HtfOQLt4QRs
Name: Tan Jin Neng, Clarence
Class: 1A3 (28)
Term 3 Science Ace
Experiment on obtaining water from salt water
Introduction:
Mixtures are not chemically joined and we can use physical methods to obtain the components of the mixture. The various separation techniques are Filtering, Chromatography, Distillation, Fractional Distillation and Evaporation.
A solution is a mixture. It is formed when a solid, a liquid or a gas dissolves in a liquid. For example, if you stir salt into water, the salt dissolves. It breaks up into individual salt molecules. The solution is now a mixture of water molecules and salt molecules. The salt is called the solute and the water is called the solvent.
Experiment set up:
As we have learnt that we can obtain a solvent from a solution using distillation, I shall do an experiment on distillation to obtain water from salt solution, not in the laboratory but at home. Since it is at home, I do not have the necessary laboratory apparatus like flask, Bunsen burner, condenser, etc, I shall make use of some kitchen utensils.
These are the things that I am going to use for the experiment: A cup of water, some salt (sodium chloride), an empty saucer, cooking pot, aluminum foil, ice cubes and a spoon.
First, I shall dissolve some salt into the water. Stir it until the salt dissolves.
Next I pour the salt solution into the cooking pot.
Place the pot onto a stove. Place the empty saucer in the cooking pot. Cover the pot with an aluminum foil and put some ice cubes on the foil.
Heat the salt solution until all the ice cubes have melted.
Remove the aluminum foil and take out the saucer from the cooking pot.
Some water is collected in the saucer. We can further test if the water is pure by boiling it. If it boils at 100°C, it means the water is pure.
Conclusion:
The melting and boiling points of salt and water are tabulated below:
Salt Water
Boiling point 1413°C 100°C
Melting point 801°C 0°C
As water has a lower boiling point than salt, 100°C (water) compared to 1413°C (salt), water evaporates first when the salt solution is heated. Water vapour condenses to form water droplets when in contact with a cool surface which is the aluminum foil with ice cubes on it. As the weight of the ice cubes form a depression on the centre of the aluminum foil, the water droplets then drip into the saucer. The salt will not evaporate yet as its boiling point is 1413°C and therefore is left in the pot.
These are the link to my videos as i cannot upload them ):
http://www.youtube.com/watch?v=xPICTyqui40
http://www.youtube.com/watch?v=eeipv9xCdtM
http://www.youtube.com/watch?v=HtfOQLt4QRs
Separation Techniques 2(:
We also did another experiment on another time on another day about Paper chromatography. It is actually using filter paper to separate inks. First, we used a pencil to draw a line across the scrip of paper which is about 3-5 cm away from the bottom. Next we drip a drop of ink onto the line. We then place the paper into a test-tube containing ethanol. Magically, the ink separated into 3 colours such as red, purple and black.
I tried doing the experiment at home using normal paper and water but it failed :(
I tried doing the experiment at home using normal paper and water but it failed :(
Separation Techniques 1
In this lesson, we were asked to separate a mixture of sand, water and salt which is also called a suspension. We poured the mixture into a filter paper which was folded in to a cone like shape. I was surprised when the filtrate came out as i thought it would still be not clear, but instead it was crystal clear. We then poured the filtrate into a evaporation disk and started boiling it. We separated salt from salt water!!!
Sunday, September 5, 2010
First time in the LAB!!!
I feel that this science lesson is very interesting as it is my first time entering the laboratory. The laboratory is filled with items used for experimenting for example, the test tubes which is kept in the side of our classrooms.
We learnt about the different signs in the lab.such as the flammable sign and explosive sign
we also brought our test-tube there and kept it at the side of the the room
We learnt about the different signs in the lab.such as the flammable sign and explosive sign
we also brought our test-tube there and kept it at the side of the the room
Friday, May 7, 2010
Science Ace
Name: Tan Jin Neng Clarence (28)
Class : 1A3
Ace assignment in term 2
Diamond and Graphite
Introduction
Allotropy or allotropism is a behavior exhibited by some chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner. Allotropes are different structural modifications of an element.
Allotropes of Carbon
Carbon has eight allotropes: a) Diamond, b) Graphite, c) Lonsdaleite, d) C60 (Buckminsterfullerene or buckyball), e) C540, f) C70, g) Amorphous carbon, and h) single-walled carbon nanotube or buckytube.
Graphite and diamond are two of the most interesting allotropes. They are identical chemically—both are composed of carbon (C), but physically, they are very different in their structure and properties.
Diamond vs Graphite
Their structure and properties differ in the following ways:
1. Appearance:
Graphite is opaque and metallic- to earthy-looking, while diamonds are transparent and brilliant. Diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other solid or liquid substance - nothing else even comes close.
2. Hardness:
The word “diamond” comes from the Greek word meaning unbreakable. Diamond is a perfect "10", defining the top of the hardness scale, and by absolute measures four times harder than sapphire (which is #9 on that scale). Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron. These tetrahedrons together form a giant 3-dimensional network of six-membered carbon rings (similar to cyclohexane), in the chair conformation, allowing for zero bond angle strain. This stable network of covalent bonds and hexagonal rings, is the reason that diamond is so incredibly strong.
On the other hand, Graphite is very soft and has a hardness of 1 to 2 on this scale. It also has a giant covalent structure but different from that of diamond. The carbon atoms are arranged in flat layers. In each layer, the carbon atoms are arranged in rings of six atoms, with each atom joined to others by strong covalent bonds. However the forces between the layers are weak and so the layers can easily slide past each other. This makes graphite soft and slippery.
Thus, Diamond is the ultimate abrasive, often used for industrial cutting and polishing tools, whereas Graphite is a very good lubricant and also used as pencil lead as the layers of atoms slide off the pencil onto the paper.
3. Thermal Conductivity
Diamond conducts heat better than anything - five times better than the second best element, Silver!
4. Electrical Conductivity
Diamond is an excellent electrical insulator as all the outer shell electrons in the atoms are used to form covalent bonds. Thus there is no free electrons and so conduction does not occur.
Graphite is the only non-metal that conducts electricity. This is due to the vast electron delocalization within the carbon layers (a phenomenon called aromaticity). These valence electrons are free to move, so are able to conduct electricity.
5. Melting Point
Both Graphite and Diamond have very high melting and boiling points because strong covalent bonds must be broken to melt and boil them.
Graphite has a higher meting point (3948 Kelvin) compared to Diamond (3820 Kelvin)
6. Crystallization
Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system.
7. Stability
Under the normal pressures and temperatures we experience on the Earth’s surface, Graphite is the stable form of carbon. In fact, diamonds are actually thermodynamically unstable, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow for humans to notice.
8. Density & Refractive Index
Diamond is more dense than graphite with density of 3.5–3.53 g/cm3 compare to graphite’s 2.09–2.23 g/cm3
Diamond is highly refractive with an index of 2.418 (at 500 nm) whereas graphite is opaque.
9. Chemical activity
Graphite is slightly more reactive than diamond. This is because the reactants are able to penetrate between the hexagonal layers of carbon atoms in graphite. It is unaffected by ordinary solvents, dilute acids, or fused alkalis.
Conclusion
Though both are carbon, they are named differently as Diamond and Graphite probably because of the above differences. Due to their distinct differences, they are used for different purposes.
"Diamonds are a girl's best friend", it is so expensive and heavily sought after in the jewellery industry because of the "four Cs": Carat (weight), Clarity, Colour and Cut. It is also rare in that only a few survived the hazardous journey from the depths of the earth to reach the earth's surface. Because of its hardness, Diamond is used in cutting other hard solids. Rock drills and saws are studded with thousands of tiny diamonds. Diamond-tipped drills are used to cut through thousands of feet of rock to reach oil and gas deep in the Earth.
Natural graphite is mostly consumed for refractories, steelmaking, expanded graphite, brake linings, and foundry facings-lubricants. They are also used as the marking material ("lead") in common pencils, in zinc-carbon batteries, in electric motor brushes, and various specialized applications.
References
http://www.galleries.com/minerals/elements/diamond/diamond.htm
http://www.galleries.com/minerals/elements/graphite/graphite.htm
http://sciencekids.co.nz/sciencefacts/chemistry/diamond.html
http://www.enmu.edu/services/museums/miles-mineral/diamond.shtml
Chemistry Insights by Dr Rex M Heyworth ISBN: 978-981-247-824-5
Diamond Graphite
Class : 1A3
Ace assignment in term 2
Diamond and Graphite
Introduction
Allotropy or allotropism is a behavior exhibited by some chemical elements: these elements can exist in two or more different forms, known as allotropes of that element. In each allotrope, the element's atoms are bonded together in a different manner. Allotropes are different structural modifications of an element.
Allotropes of Carbon
Carbon has eight allotropes: a) Diamond, b) Graphite, c) Lonsdaleite, d) C60 (Buckminsterfullerene or buckyball), e) C540, f) C70, g) Amorphous carbon, and h) single-walled carbon nanotube or buckytube.
Graphite and diamond are two of the most interesting allotropes. They are identical chemically—both are composed of carbon (C), but physically, they are very different in their structure and properties.
Diamond vs Graphite
Their structure and properties differ in the following ways:
1. Appearance:
Graphite is opaque and metallic- to earthy-looking, while diamonds are transparent and brilliant. Diamond is transparent over a larger range of wavelengths (from the ultraviolet into the far infrared) than is any other solid or liquid substance - nothing else even comes close.
2. Hardness:
The word “diamond” comes from the Greek word meaning unbreakable. Diamond is a perfect "10", defining the top of the hardness scale, and by absolute measures four times harder than sapphire (which is #9 on that scale). Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron. These tetrahedrons together form a giant 3-dimensional network of six-membered carbon rings (similar to cyclohexane), in the chair conformation, allowing for zero bond angle strain. This stable network of covalent bonds and hexagonal rings, is the reason that diamond is so incredibly strong.
On the other hand, Graphite is very soft and has a hardness of 1 to 2 on this scale. It also has a giant covalent structure but different from that of diamond. The carbon atoms are arranged in flat layers. In each layer, the carbon atoms are arranged in rings of six atoms, with each atom joined to others by strong covalent bonds. However the forces between the layers are weak and so the layers can easily slide past each other. This makes graphite soft and slippery.
Thus, Diamond is the ultimate abrasive, often used for industrial cutting and polishing tools, whereas Graphite is a very good lubricant and also used as pencil lead as the layers of atoms slide off the pencil onto the paper.
3. Thermal Conductivity
Diamond conducts heat better than anything - five times better than the second best element, Silver!
4. Electrical Conductivity
Diamond is an excellent electrical insulator as all the outer shell electrons in the atoms are used to form covalent bonds. Thus there is no free electrons and so conduction does not occur.
Graphite is the only non-metal that conducts electricity. This is due to the vast electron delocalization within the carbon layers (a phenomenon called aromaticity). These valence electrons are free to move, so are able to conduct electricity.
5. Melting Point
Both Graphite and Diamond have very high melting and boiling points because strong covalent bonds must be broken to melt and boil them.
Graphite has a higher meting point (3948 Kelvin) compared to Diamond (3820 Kelvin)
6. Crystallization
Diamond crystallizes in the Isometric system and graphite crystallizes in the hexagonal system.
7. Stability
Under the normal pressures and temperatures we experience on the Earth’s surface, Graphite is the stable form of carbon. In fact, diamonds are actually thermodynamically unstable, all diamonds at or near the surface of the Earth are currently undergoing a transformation into Graphite. This reaction, fortunately, is extremely slow for humans to notice.
8. Density & Refractive Index
Diamond is more dense than graphite with density of 3.5–3.53 g/cm3 compare to graphite’s 2.09–2.23 g/cm3
Diamond is highly refractive with an index of 2.418 (at 500 nm) whereas graphite is opaque.
9. Chemical activity
Graphite is slightly more reactive than diamond. This is because the reactants are able to penetrate between the hexagonal layers of carbon atoms in graphite. It is unaffected by ordinary solvents, dilute acids, or fused alkalis.
Conclusion
Though both are carbon, they are named differently as Diamond and Graphite probably because of the above differences. Due to their distinct differences, they are used for different purposes.
"Diamonds are a girl's best friend", it is so expensive and heavily sought after in the jewellery industry because of the "four Cs": Carat (weight), Clarity, Colour and Cut. It is also rare in that only a few survived the hazardous journey from the depths of the earth to reach the earth's surface. Because of its hardness, Diamond is used in cutting other hard solids. Rock drills and saws are studded with thousands of tiny diamonds. Diamond-tipped drills are used to cut through thousands of feet of rock to reach oil and gas deep in the Earth.
Natural graphite is mostly consumed for refractories, steelmaking, expanded graphite, brake linings, and foundry facings-lubricants. They are also used as the marking material ("lead") in common pencils, in zinc-carbon batteries, in electric motor brushes, and various specialized applications.
References
http://www.galleries.com/minerals/elements/diamond/diamond.htm
http://www.galleries.com/minerals/elements/graphite/graphite.htm
http://sciencekids.co.nz/sciencefacts/chemistry/diamond.html
http://www.enmu.edu/services/museums/miles-mineral/diamond.shtml
Chemistry Insights by Dr Rex M Heyworth ISBN: 978-981-247-824-5
Diamond Graphite
Saturday, May 1, 2010
Why ice float on water
Although water has a density of 1g/cm3, ice will still float on it as its density is lower than water. When water freezes to ice, the volume increase. For example, if water is frozen in a glass jar, the glass jar breaks. Using the kinetic particle theory, when a substance is in a solid state, the particles are closely packed in an orderly manner.Thus the density of solid is higher than liquids. However, for ice it is in the opposite manner. There are empty spaces within the ice structure, which translates to a more open or expanded structure. The ice structure takes up more volume than the liquid water molecules, hence ice is less dense than liquid water.
In conclusion, when water is frozen into ice, the volume increases while the mass is kept the same so the density will be lesser than 1g/cm3. Therefore, ice float on water.
Comparison of Liquid water and ice:
Mass of water = 100 g
Mass of ice = 100 g
Volume of water = 100 mL
Volume of ice = ? mL
Density of water = 1.0 g/mL
Density of ice = 0.92 g/mL
The volume of ice is therefore 100x 1.0/0.92 = 108.7 cm3. Which is 8.7cm3 more than water.
In conclusion, when water is frozen into ice, the volume increases while the mass is kept the same so the density will be lesser than 1g/cm3. Therefore, ice float on water.
Comparison of Liquid water and ice:
Mass of water = 100 g
Mass of ice = 100 g
Volume of water = 100 mL
Volume of ice = ? mL
Density of water = 1.0 g/mL
Density of ice = 0.92 g/mL
The volume of ice is therefore 100x 1.0/0.92 = 108.7 cm3. Which is 8.7cm3 more than water.
Sunday, February 28, 2010
home learning
Substances with lower densities will float in substances with higher densities. The egg had a higher density then water so it sank. But when salt was added, the density of the water, which became salt water, was higher than the egg's, so the egg started to float
Usually, a substance with lower density will float in substances with higher density. In the first part of the experiment, egg sunk in water, this happen because egg has higher density than water. At the second part of the experiment, egg floated on the salt water, this happens as salt raises the density by adding more mass, to the same volume of water. Thus, the egg float.
Usually, a substance with lower density will float in substances with higher density. In the first part of the experiment, egg sunk in water, this happen because egg has higher density than water. At the second part of the experiment, egg floated on the salt water, this happens as salt raises the density by adding more mass, to the same volume of water. Thus, the egg float.
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