Saturday, 17 September 2011
Excursion to Macritchie reservoir
We had an excursion to Macritchie reservoir. It was very fun and enjoyable, because of the wind and the cool calm motion of the waves of the water. We went there to do our project about water conservation. We learnt about the four taps: distillation, New water, imported water like Malaysia and reservoirs. We were lead around by our secondary four seniors, and we were to embark on an IDS project on water conservation. After the excursion, we decided to do as a group with Huai Ze, Kenneth and Yu Kheng. we were to do a brochure as well as a poster to promote water conservation. It was a very enjoyable experience as we met up at Kenneth's house and we discussed about the project. Even though we may have had certain misunderstandings as well as disagreements, the project was still purposeful and useful to us. We came up with the idea of giving a lot of information in our poster, but it did not turn out correctly, because there were few or little pictures and the poster was not enticing at all, ending up looking more like and information booklet cover. in the end we decided to include some photos of water conservation, such as new water and reservoirs, so that people would like to see our poster. We included information, but we spread it out such that the information was not overloaded, but yet there was still plenty of information to supply the people with what they want to know and what they need to know in order to play their part in conserving water in Singapore. Overall, i think that the excursion and the project served its purpose. I learnt that we need to conserve water, because we are running out of it and Malaysia might not be supplying us with water in the future. We need to prepare for ourselves and be independent.
Term three and term three test
In term three, we were presented with a variety of new topics, some of which we had done before when we were in primary school, like cells, moving waters, bouncy raw egg, extracting chlorophyll and artificial small intestines.
----Cells----
In our practical on cells, we were to try to see our cheek cells under a microscope.I felt that this experiment was fun because we had to make use of toothpicks and we had to scrape our skin cells off our cheeks. We managed to see our cheek cells, even though it was not clear. The iodine was useful because it helped us to see the cells more clearly. Also, the glass slips that we were provided was not very good because it broke easily and I cut myself when my glass slip broke, and so I was unable to see the cells.In part B, I felt that the cell that we were using was much more interesting than the cheek cell. Using an onion skin cell was fun because of the process required to acquire the onion skin. We had to get a scale leaf and then peel out the skin using forceps and it was fun because we squeezed juice out of the onion itself. The practical was enjoyable and exciting.
Besides that we also did practicals on bouncy raw egg. During this practical, I was sick so I was unable to make my very own bouncy raw egg. However, I still managed to find out how the bouncy raw egg was made. The egg had to react with the dilute hydrochloric acid and become soft and smelly. The egg looked peculiar, but it managed to bounce, and the liquid in the egg did not leak out of the egg.
We also did a practical on artificial intestines. The experiment was to find out why food needs to be digested. After the practical, we were also presented with homework. We were to create our own power point on the digestive system, and we had to share it with the class. In the power point, i did the part on the small intestines, including the duodenum, the jejunum, and the ilium. I made use of google as well as power point to do it. it was fun and exciting, even though we did not manage to meet up properly, nor discuss properly.
here is my powerpoint presentation. click on it and go to the link to see my power point.
Digestive system 2
It was a lot of fun doing the presentation and I learnt a lot. I learnt a lot about the small intestines, because I was the one who did the part. I learnt about the duodenum, the jejunum and the ilium. I learnt about where they were found and also their functions.
It was a lot of fun doing the presentation and I learnt a lot. I learnt a lot about the small intestines, because I was the one who did the part. I learnt about the duodenum, the jejunum and the ilium. I learnt about where they were found and also their functions.
----Transfer of thermal energy----
Soon after, we started to learn about the transfer of thermal energy. We also did a practical, transfer of thermal energy. It was interesting because it involved the use of a multilog, which I had never used before. We learnt a lot from the experiment, about the difference between the cans that are black and silver. Because of the black covering, one of the tins was hotter than the other one.
In the term three test, we were presented with the topics I mentioned at the start of the post. Even though it was an easy test, and many people got thirty plus marks, and yet i did not do well for the test. I fell so low that I actually got the lowest in class, yet again. i got 20 over 40. I had not read the questions properly, so when they asked for which one was a mixture and which one was a compound, I wrote the ones for compound in the mixture column and I wrote the ones for mixture in the compounds column. Other than that, every one of my questions were not phrased properly, so either one or half mark was deducted from each questions, with some of the questions even getting 0. I did not read the notes that Mr low presented to us properly. I had studied only 5 days before the test. Thus the information could not all go into my head. Those that I didn't not study properly for came out, and those that I studied for did not, or came out only occasionally. I learnt that we should never study only days before the test, but should revise every time we go home after a science lesson so that we will not forget everything that Mr Low had said in class. If we do not do that, we will forget everything we learn and will end up failing, or getting very low marks for our tests.
In the term three test, we were presented with the topics I mentioned at the start of the post. Even though it was an easy test, and many people got thirty plus marks, and yet i did not do well for the test. I fell so low that I actually got the lowest in class, yet again. i got 20 over 40. I had not read the questions properly, so when they asked for which one was a mixture and which one was a compound, I wrote the ones for compound in the mixture column and I wrote the ones for mixture in the compounds column. Other than that, every one of my questions were not phrased properly, so either one or half mark was deducted from each questions, with some of the questions even getting 0. I did not read the notes that Mr low presented to us properly. I had studied only 5 days before the test. Thus the information could not all go into my head. Those that I didn't not study properly for came out, and those that I studied for did not, or came out only occasionally. I learnt that we should never study only days before the test, but should revise every time we go home after a science lesson so that we will not forget everything that Mr Low had said in class. If we do not do that, we will forget everything we learn and will end up failing, or getting very low marks for our tests.
Monday, 22 August 2011
Term 2 chapters and term 2 test
In term 2, we started to learn about density of irregular objects, Brownian motion, elements, compounds and mixtures and forming compounds. These many topics spurred my interest with their weird names.
----Density of an irregular object----
In density of an irregular object, we had to find the density of objects such as glass stoppers. We were to lower them into measuring cylinders and measure their densities. I felt that this practical lesson was very fun because it actually helped us to learn about calculations. Although the math behind it was easy, however it was still interesting how you had to subtract the volumes to get the volume of the irregular object. I was unable to really do the experiment properly with Samuel Leong because when we dropped the stopper in, we accidentally displaced some of the water in the measuring cylinder, hence the calculation error.We did not lower the glass stopper gently into the measuring cylinder, but had dropped in without even holding on to the string connected to the glass stopper.
However, the practical was still a fun and enjoyable one. We still learnt much about densities of irregular objects. Even though we fooled around with the apparatus, yet we still managed to grasp what the teacher was trying to teach us, which was to find the density of the objects that was irregular.We were fascinated by the densities
of such irregular objects and we learnt a lot about it. The math behind finding density was easy and yet it fascinated me. I had not realized how such simple math could be used to find densities of weird objects. You simply had to find the volume of water before and after the glass stopper is put into it, and subtract the latter from the first and you will get the density of the glass stopper.
----Brownian motion----
During our practical on Brownian motion, we were to observe the Brownian motion of smoke particles in the air. We had to fill a smoke cell with smoke from a smouldering paper and cover it with a glass slip and then illuminate the smoke particles and examine the results. We found out how there were bright spots of light and they were zigzagging in random directions and we found out that they were actually smoke particles and reflect light from the source. We also realized how the bright spots are moving because the air particles bombard unevenly on all sides of the smoke particles causing random and continuous movement.
To find out which are larger particles and which are smaller particles, we can simply look at their speed because larger particles will move slower than smaller particles because they have a larger inertia.
In our practical, we were presented with a new and fascinating question about how we could observe Brownian motion in liquid. I could not figure out anyway to do it, but in the end here is the answer. suspend talcum powder in water and observe the movement under a light source and a powerful microscope.
Interesting facts about Brownian motion: Brownian motion was named after the Scottish botanist Robert Brown who first observed it in 1827. He was using a microscope to look at pollen grains in water, when he noticed that the pollen grains kept moving about. At first he thought that the pollen was alive so he boiled it and tried again but they still moved. Brownian motion provides good evidence that gas consists of invisible molecules moving around randomly at high speeds.
It was very interesting to see the particles zigzag about in high speed. In the above picture, we can see what I really mean when I say that the particles zigzag about in random directions.
----Elements, compounds and mixtures----
In our practical about investigating mixtures and compounds we had to investigate the properties of a mixture and a compound. We made use of a tripod stand, evaporating dish, glass rod as well as wire gauze and Bunsen burner. We also made use of iron filings, sulfur powder, filter paper and a piece of paper magnet.
We used the magnet to try to attract the sulfur powder. nothing happened and the sulfur remained yellow. Then we used the magnet and tried to attract the iron filings, resulting in the filings getting attracted to the magnet. Then we mixed the iron filings and the sulfur powder together and mixed them with a glass rod. We see that it is a mixture of iron filings and sulfur powder. The iron filings are separated from the sulfur powder. Thus we can see how mixtures are not chemically combined and can be separated without chemical means, which in this case is represented by the magnet.
Then we needed to prove compounds and their properties. We heated the evaporating dish we used to show mixtures over a Bunsen burner and observed the compound formed. It was a dark grey solid. When we moved the magnet over to the compound, there was no observable changes and nothing was attracted to the magnet. Thus we can prove how a compound is made through chemical means and cannot be separated using physical methods such as using the magnet.The experiment was not an easy one, because of the powder and the iron filings. they were small and were in such great numbers that they were spilling all over the floor in the laboratory. Also, we made quite a mess when we were trying to make the compound because we were heating the mixture and they sprayed everywhere. Also when the sulfur was heated it gave off such a stench that we had headaches and we could not see what we were doing. We could only hold on to our noses and try not to puke. The sulfur smelt like rotten eggs and rotten fish! However it was a fun practical because it involved a lot of the Bunsen burner as well as mixing stirring the iron filings and the sulfur powder together.
After the practical, We learnt that mixture retains the properties of its constituents, but compounds do not retain the properties of its constituents. I also learnt how heat or light energy is needed for a compound to form, but for mixtures heat and light energy is not required.When surfing the internet, I came across several questions that required thinking processes. These questions may not be ones that are asked in tests, but they are still interesting.
An unknown, clear liquid is given to you in a beaker. You transfer the liquid from the beaker to a clean, empty test-tube, and begin to heat it. After a while, you see vapors (which on further analysis you discover are vapors of water) rising from the test-tube, and pretty soon, all that's left are a few crystals of salt stuck to the edges! Was that liquid an element, compound or a mixture?
A dish is given to you, which contains a blackish-yellow powder. When you move a magnet over it, you are amazed to see black particles, (which you find out are iron) fly upwards and get stuck to the magnet, and all that's left in the dish is a yellow powder, which you discover to be sulphur (sulfur). Was your original powder an element, compound or mixture?
PART B Reacting an element with a compound
In this part of the experiment we were to place half a spatula of iron filings in a test tube and dilute sulfuric acid to the depth off about 2 cm. Then we saw that iron filings are dissolving into the sulfuric acid and bubbles are forming. A new substance has formed because the test tube felt warm so there was heat energy involved. From this I can learn how sulfuric acid reacts with iron filings.
PART C reacting two compounds
We placed sodium chloride solution in a test tube. WE used a dropper and added lead (II) nitrate slowly to the test tube.WE saw white precipitate in the colorless solution.
lead(II) nitrate + sodium chloride = lead(II) chloride + sodium nitrate. After the excercies we were told to stats three differences between metals and non metals
Metals are good electrical and thermal conductors but non metals are not. Metals are ductile but non metals are not ductile.
UESES OF SOME PURE METALS
summary of this passage is:
Aluminumis a light metal that can be easily rolled out into very thin yet strong sheets. It is resistant to corrosion, which makes it suitable for milk bottle caps. It does not melt easily and can withstand high temperatures, which is why it is used to make containers for prepacked foods and for making foil for covering the food it cooks. Many drink cans are also made of aluminum.
Copper is good at conducting electricity and is ductile. It can be pulled into thin wire. So copper is used for making electrical wires. Gold, silver and platinum are used for making jewellery and they are unreactive metals that stay shiny. They can be used to make the coating parts in electrical switches.
Mercury is an unusual metal that is liquid at room temperature. It is used in thermometers.
Lead is a heavy metal which is extremely malleable and it is used for waterproof edging to roofs such as chimneys. before it was known to be poisonous it was used for making water pipes and toy soldiers. Lead is also used for shielding radiation.
Titanium can be used to make ships, glass covers or laptops because it is a durable material.
----WHICH CAN DISSOLVE MORE----
The practical was to find out if the solubility of different solutes differ in the same solvent. We had to keep the volume, mass and temperature of the solvent constant. We measured 20 cm cube of water into a beaker, and added 1 g of common salt using the electronic balance. We added the common salt to the water, then stirred the common salt in the water and continued adding 1 g of salt until no more will dissolve in the stirring. the total mass of the salt added before it would not dissolve is about 5 g. I repeated the steps 1 to 4 using baking soda and iodine crystals, and the results were 1 and 0 respectively, so I learnt that salt is the most soluble in water. adding 0.1 g of salt to the water could help me to find the solubility of the solutes in a solvent more accurately. From the experiment I can conclude that different solutes have different solubility.
----Separating techniques----
This experiment was for me to separate a mixture of salt and sand. i made use of beakers, filter funnels, glass rods, evaporating dishes, tripod stand, wire gauze, Bunsen burner and a retort stand. I also made use of a mixture of salt and sand and filter paper. My task was to separate a mixture of salt and sand. Salt can be dissolved but sand cannot. I had to make use of water and filtration and dryness to separate them. I was supposed to place a mixture of salt and sand in a beaker and add 10cm cube of water into the beaker and add more water to dissolve the salt if necessary.Using filtration, sand is separated from the mixture. Using evaporation to dryness, salt is separated from the mixture.
Chromatography
A question to find out if black ink is really black. The aim of the experiment was to find out the colors in different brands of black ink. This experiment was very practical and I learnt a lot about chromatography from it. I learnt about how you should never place the ethanol and water mixture above the ink dots to prevent a mistake in the results of the experiment. I also learnt how the dots should have a fixed difference from the end of the paper, which in this case is three centimeters.The experiment was very effective and successful and i was able to see the different colors of the black ink which was blue yellow and purple, along with a mix of brown and green. In the discussion section there was a question discussing about chromatography used on chocolate. i felt that it would be useful to learn about it and hoped that one day i would be able to do something like that. The experiment really helps in finding out the colors in the chocolate. The experiment was meant to inform us and teach us about the uses of chromatography and how to use it. I have learnt a lot from the practical about the experiment.
----TERM TEST 2----
the term 2 test was harder than the term test one but it was easier to comprehend than the first test, so I feel. the questions that came out were easy to understand and I also felt that the questions that came out were more and had lesser marks in each of them, so it was easier to get the marks. I felt that the questions were clear and concise. Even though my results were not as good as they were in test 1, yet I still improved while doing the test, and i got 28 and a half over 40. I feel that if I had studied the notes that were presented to me more conscientiously I would have been able to score higher in the test itself. i feel that the graph question was mark leniently and thus I was able to salvage marks to pull up my total score.
----Density of an irregular object----
In density of an irregular object, we had to find the density of objects such as glass stoppers. We were to lower them into measuring cylinders and measure their densities. I felt that this practical lesson was very fun because it actually helped us to learn about calculations. Although the math behind it was easy, however it was still interesting how you had to subtract the volumes to get the volume of the irregular object. I was unable to really do the experiment properly with Samuel Leong because when we dropped the stopper in, we accidentally displaced some of the water in the measuring cylinder, hence the calculation error.We did not lower the glass stopper gently into the measuring cylinder, but had dropped in without even holding on to the string connected to the glass stopper.
of such irregular objects and we learnt a lot about it. The math behind finding density was easy and yet it fascinated me. I had not realized how such simple math could be used to find densities of weird objects. You simply had to find the volume of water before and after the glass stopper is put into it, and subtract the latter from the first and you will get the density of the glass stopper.
----Brownian motion----
During our practical on Brownian motion, we were to observe the Brownian motion of smoke particles in the air. We had to fill a smoke cell with smoke from a smouldering paper and cover it with a glass slip and then illuminate the smoke particles and examine the results. We found out how there were bright spots of light and they were zigzagging in random directions and we found out that they were actually smoke particles and reflect light from the source. We also realized how the bright spots are moving because the air particles bombard unevenly on all sides of the smoke particles causing random and continuous movement.
To find out which are larger particles and which are smaller particles, we can simply look at their speed because larger particles will move slower than smaller particles because they have a larger inertia.
In our practical, we were presented with a new and fascinating question about how we could observe Brownian motion in liquid. I could not figure out anyway to do it, but in the end here is the answer. suspend talcum powder in water and observe the movement under a light source and a powerful microscope.
Interesting facts about Brownian motion: Brownian motion was named after the Scottish botanist Robert Brown who first observed it in 1827. He was using a microscope to look at pollen grains in water, when he noticed that the pollen grains kept moving about. At first he thought that the pollen was alive so he boiled it and tried again but they still moved. Brownian motion provides good evidence that gas consists of invisible molecules moving around randomly at high speeds.
----Elements, compounds and mixtures----
In our practical about investigating mixtures and compounds we had to investigate the properties of a mixture and a compound. We made use of a tripod stand, evaporating dish, glass rod as well as wire gauze and Bunsen burner. We also made use of iron filings, sulfur powder, filter paper and a piece of paper magnet.
We used the magnet to try to attract the sulfur powder. nothing happened and the sulfur remained yellow. Then we used the magnet and tried to attract the iron filings, resulting in the filings getting attracted to the magnet. Then we mixed the iron filings and the sulfur powder together and mixed them with a glass rod. We see that it is a mixture of iron filings and sulfur powder. The iron filings are separated from the sulfur powder. Thus we can see how mixtures are not chemically combined and can be separated without chemical means, which in this case is represented by the magnet.
Then we needed to prove compounds and their properties. We heated the evaporating dish we used to show mixtures over a Bunsen burner and observed the compound formed. It was a dark grey solid. When we moved the magnet over to the compound, there was no observable changes and nothing was attracted to the magnet. Thus we can prove how a compound is made through chemical means and cannot be separated using physical methods such as using the magnet.The experiment was not an easy one, because of the powder and the iron filings. they were small and were in such great numbers that they were spilling all over the floor in the laboratory. Also, we made quite a mess when we were trying to make the compound because we were heating the mixture and they sprayed everywhere. Also when the sulfur was heated it gave off such a stench that we had headaches and we could not see what we were doing. We could only hold on to our noses and try not to puke. The sulfur smelt like rotten eggs and rotten fish! However it was a fun practical because it involved a lot of the Bunsen burner as well as mixing stirring the iron filings and the sulfur powder together.
After the practical, We learnt that mixture retains the properties of its constituents, but compounds do not retain the properties of its constituents. I also learnt how heat or light energy is needed for a compound to form, but for mixtures heat and light energy is not required.When surfing the internet, I came across several questions that required thinking processes. These questions may not be ones that are asked in tests, but they are still interesting.
An unknown, clear liquid is given to you in a beaker. You transfer the liquid from the beaker to a clean, empty test-tube, and begin to heat it. After a while, you see vapors (which on further analysis you discover are vapors of water) rising from the test-tube, and pretty soon, all that's left are a few crystals of salt stuck to the edges! Was that liquid an element, compound or a mixture?
- mixture. The constituents of a mixture can easily be separated by physical processes, which in this case, was the application of heat. The salt had been dissolved in the water to form a true solution of common salt, where the particles of salt were invisible through the naked eye as well as through a microscope, resulting in the solution being absolutely clear.
- mixture. Aqua regia was a mixture of concentrated nitric acid (HNO3) and hydrochloric acid (HCl) and was used to dissolve gold, which would leave silver.
A dish is given to you, which contains a blackish-yellow powder. When you move a magnet over it, you are amazed to see black particles, (which you find out are iron) fly upwards and get stuck to the magnet, and all that's left in the dish is a yellow powder, which you discover to be sulphur (sulfur). Was your original powder an element, compound or mixture?
- mixture. The powder was a mixture of sulphur, which is yellow in colour, and iron, which is magnetic and blackish in colour. When the magnet was passed over the mixture, the iron got attracted to it, leaving the sulphur in the dish. Hence in mixtures, the properties of the constituents aren't lost. this question was related to a topic that we went through about elements, compounds and mixtures.
| You have just won a block of pure 24-carat gold. Have you just procured an element, compound or mixture? |
- element. Gold, like oxygen, hydrogen and over 100 other substances is classified as an element. Elements are further grouped into metals, non-metals and metalloids. 22-carat (or "karat") gold, or 22 parts of gold alloyed with 2 parts of silver or copper, is usually preferred to 24-carat (pure) gold in jewellery.
| *Water* is what all life in the world depends on. Is it an element, compound or mixture? |
- compound. A molecule of water is made up of two atoms of hydrogen and one atom of oxygen, which means that it is made up of more than one kind of atom, and hence isn't an element. Also, since it can only be broken down into hydrogen and oxygen (its constituent elements) by chemical processes (such as electrolysis), it is a compound.
- Although these questions were easy and comprehensible, they contained the basics of elements compounds and mixtures and were thus worthy of reading. In the above I have mentioned questions on elements, compounds and mixtures. these questions provide basic understanding on the properties of compounds, mixtures and elements.
- ----Forming Compounds----
- In this practical, we were to investigate the formation of compounds by reacting two elements, reacting an element with a compound and reacting two compounds. We made use of magnesium ribbon, iron filings, dilute sulfuric acid, lead(II) nitrate solution and sodium chloride.
- PART A
- We had to burn the magnesium ribbon over a Bunsen burner and when it catches fire we were to hold it over an evaporating dish to collect the ashes formed and record our observations. We realized how the magnesium ribbon burned with a bright white light. The ashes are a powdery white substance.( Ash is white in color.) Then, a new substance is formed because the physical appearance has changed from silvery grey to white in color and heat is also involved in this reaction.In the compound, oxygen combined with magnesium to get the new compound. Or it can be stated with this:
- magnesium + oxygen--------> magnesium oxide.
PART B Reacting an element with a compound
In this part of the experiment we were to place half a spatula of iron filings in a test tube and dilute sulfuric acid to the depth off about 2 cm. Then we saw that iron filings are dissolving into the sulfuric acid and bubbles are forming. A new substance has formed because the test tube felt warm so there was heat energy involved. From this I can learn how sulfuric acid reacts with iron filings.
PART C reacting two compounds
We placed sodium chloride solution in a test tube. WE used a dropper and added lead (II) nitrate slowly to the test tube.WE saw white precipitate in the colorless solution.
lead(II) nitrate + sodium chloride = lead(II) chloride + sodium nitrate. After the excercies we were told to stats three differences between metals and non metals
Metals are good electrical and thermal conductors but non metals are not. Metals are ductile but non metals are not ductile.
UESES OF SOME PURE METALS
summary of this passage is:
Aluminumis a light metal that can be easily rolled out into very thin yet strong sheets. It is resistant to corrosion, which makes it suitable for milk bottle caps. It does not melt easily and can withstand high temperatures, which is why it is used to make containers for prepacked foods and for making foil for covering the food it cooks. Many drink cans are also made of aluminum.
Copper is good at conducting electricity and is ductile. It can be pulled into thin wire. So copper is used for making electrical wires. Gold, silver and platinum are used for making jewellery and they are unreactive metals that stay shiny. They can be used to make the coating parts in electrical switches.
Mercury is an unusual metal that is liquid at room temperature. It is used in thermometers.
Lead is a heavy metal which is extremely malleable and it is used for waterproof edging to roofs such as chimneys. before it was known to be poisonous it was used for making water pipes and toy soldiers. Lead is also used for shielding radiation.
Titanium can be used to make ships, glass covers or laptops because it is a durable material.
----WHICH CAN DISSOLVE MORE----
The practical was to find out if the solubility of different solutes differ in the same solvent. We had to keep the volume, mass and temperature of the solvent constant. We measured 20 cm cube of water into a beaker, and added 1 g of common salt using the electronic balance. We added the common salt to the water, then stirred the common salt in the water and continued adding 1 g of salt until no more will dissolve in the stirring. the total mass of the salt added before it would not dissolve is about 5 g. I repeated the steps 1 to 4 using baking soda and iodine crystals, and the results were 1 and 0 respectively, so I learnt that salt is the most soluble in water. adding 0.1 g of salt to the water could help me to find the solubility of the solutes in a solvent more accurately. From the experiment I can conclude that different solutes have different solubility.
----Separating techniques----
This experiment was for me to separate a mixture of salt and sand. i made use of beakers, filter funnels, glass rods, evaporating dishes, tripod stand, wire gauze, Bunsen burner and a retort stand. I also made use of a mixture of salt and sand and filter paper. My task was to separate a mixture of salt and sand. Salt can be dissolved but sand cannot. I had to make use of water and filtration and dryness to separate them. I was supposed to place a mixture of salt and sand in a beaker and add 10cm cube of water into the beaker and add more water to dissolve the salt if necessary.Using filtration, sand is separated from the mixture. Using evaporation to dryness, salt is separated from the mixture.
Chromatography
A question to find out if black ink is really black. The aim of the experiment was to find out the colors in different brands of black ink. This experiment was very practical and I learnt a lot about chromatography from it. I learnt about how you should never place the ethanol and water mixture above the ink dots to prevent a mistake in the results of the experiment. I also learnt how the dots should have a fixed difference from the end of the paper, which in this case is three centimeters.The experiment was very effective and successful and i was able to see the different colors of the black ink which was blue yellow and purple, along with a mix of brown and green. In the discussion section there was a question discussing about chromatography used on chocolate. i felt that it would be useful to learn about it and hoped that one day i would be able to do something like that. The experiment really helps in finding out the colors in the chocolate. The experiment was meant to inform us and teach us about the uses of chromatography and how to use it. I have learnt a lot from the practical about the experiment.
----TERM TEST 2----
the term 2 test was harder than the term test one but it was easier to comprehend than the first test, so I feel. the questions that came out were easy to understand and I also felt that the questions that came out were more and had lesser marks in each of them, so it was easier to get the marks. I felt that the questions were clear and concise. Even though my results were not as good as they were in test 1, yet I still improved while doing the test, and i got 28 and a half over 40. I feel that if I had studied the notes that were presented to me more conscientiously I would have been able to score higher in the test itself. i feel that the graph question was mark leniently and thus I was able to salvage marks to pull up my total score.
Wednesday, 10 August 2011
Term one chapters
Hello everyone I am Ong Sim Hao from class 1i1 and in this blog I will be sharing with you about science that I have learnt in the three terms that I have been in Hwa Chong.
First off let us start with the first few weeks that we went into hwa chong. We were still young and happy, and there was nothing that we weren't curious about. Imagine our fascination when we first stepped into the laboratory. There we first met our science teacher Mr low. Mr Low taught us many things in our first year in Hwa chong.
But before we started on any chapters, we were presented with such a worksheet about < GETTING TO KNOW THE SCIENCE LABORATORY> In this worksheet was many symbols and signs, many of which I did not understand. For example, the symbol standing for explosives, was represented by a picture of a circular object getting blown up. Whereas a symbol for toxic materials was represented by a skull with two bones crossed behind it. Such symbols sparked my interest. How science could be represented by symbols, how danger could be compressed into shapes... I was amazed. With this came the interest for science.
I remember after learning about how we should be careful when we see the symbols represented in the worksheet, I was amazed and scared at the same time.
Whereas a symbol for toxic materials was represented by a skull with two bones crossed behind it. Such symbols sparked my interest. How science could be represented by symbols, how danger could be compressed into shapes... I was amazed. With this came the interest for science.
I remember after learning about how we should be careful when we see the symbols represented in the worksheet, I was amazed and scared at the same time. How could such an innocent looking laboratory possibly contain so much dangers?
as such, we were given a mini quiz after that about each and every symbol in the laboratory. Guess what I got?
Anyway, the quiz was actually more of a small test to see our standards and where we stand in the class, as well s to see how much we know. Unfortunately, I didn't know much. In the end I got 7 over 15 for the test, I think.
For our first term, we were to learn about flames as well as about density and pendulum.
----flames----
For flames, we were learning about how there was a luminous flame as well as a non luminous flame. We were to compare the flames, as well as to analyse them and find out how to get each flame.
When using the Bunsen burner, to prevent a strike back, how we should not fully open or close the air holes located at the base of the Bunsen burner.
----measurement of time-pendulum----
Besides that, we also learnt about pendulums, about terms used on pendulums, like the bob, the period, as well as an oscillation. We learnt to find out what the period of the pendulum bob was, and what oscillation meant. From this lesson I learnt about how pendulum worked, as well as why people would use pendulums. It occurred to me how the metronome used while playing the piano sounded like the pendulum, which seemed to emphasis another use of the pendulum.
- Bob is the word used to talk about the ball at the bottom the string. It must be placed at the bottom of the string to be able to count the number of oscillations made by the pendulum. The heavier the bob, the more the oscillations Also, the higher the bob is lifted, the more oscillations there will be.
-Oscillation means the period where the bob moves a complete two swings. In the diagram above, the oscillation means when the bob moves from point A to C and back to A.
- The period is the time taken for the pendulum to make one full oscillation, when the bob moves from A to C and back to A
- the frequency* is the number of oscillations the simple pendulum completes in one second.
* note the difference between the frequency and the period. The period is different from the frequency because the frequency gives the pendulum a certain time limit to see how many oscillations are made whereas the period does not give a fixed timing.
Also, from some science research I could fully understand the uses of a pendulum, like how it is used to keep track of time,
----Density----
Also, in the term test, density was tested. We were to find out densities of regular objects. We were to make use of micrometer screw gauges and marbles in a small plastic bottle. When I was doing the experiment, I felt that the experiment really showed how density could be counted out just by using three simple materials. When I had first come into the lab, I had only a brief knowledge of density and what it was. I did not even know how to calculate the density of certain objects. but after the lesson, I learnt how to use a micrometer screw gauge as well as how to find density of an object.
the laboratory is probably a very efficient means of getting things sorted out in your head because of the practicals involved. You simply had to weigh the marbles and then make use of the given equation, V=4/3pi(d/2)* * is 3 and then you can find the density of a marble. All the steps were provided for us.
----term test----
Now that I have addressed all topics that came out in the term test one, let me now share with all of you about the term one test. In the term one test, the topics that came out were the ones that I had elaborated on above. The only difference was the way Mr low tweaked the questions so that they weren't quite the same as the ones we had practiced before. Nevertheless, many of us still scored well for the first test. EXCEPT ME! For that test I scored 23 and a half out of 40.
Why didn't i do well? I asked myself. After analyzing my test paper, I realized that most of my mistakes were due to my carelessness or I had not read up on my facts. My whole test paper was filled with crosses and zeroes, and I was dumbstruck.
I analyzed the test paper and I realized that the reason I had not scored well for the test was because I had not studied well. Most of the facts I got was either wrong or wrongly phrased. The calculations I made with density questions were wrong to the extent that no method marks could be given. I had forgotten to add something, or had added something extra, resulting in a total mess in the results I had received. For the multiple choice questions, I had only got 10 over 15 and I had not done well in section B either.
After the test was done was returned to us, I reflected upon how I had studied for the test and compared it to the results I had obtained. I had not studied properly and had only done meagre amounts of exercises, resulting in the fact that I got the lowest in class for the test and had only gotten 23 and a half over 40. Also, I had not read up on the notes that were handed to us in huge stacks by Mr Low and so I was unsure of the way I should have phrased my answers when the questions came out in section B of the test.
Subscribe to:
Posts (Atom)