Friday, September 3, 2010
♥ Term 3 reflection
Just like the other two terms, term 3 was buzzing with activities. During this term, I have learnt about "Elements, Compounds and Mixtures". I am not good with them as I have not really grasped hold of their properties. I think that I have to take special attention of my compounds. During e-learning, I understood my separation techniques well so I don't think that this topic is going to be an obstacle for me. However, I think I have to get my keywords correctly.
8:47 AM
Friday, August 13, 2010
♥ Reverse Osmosis
11:35 PM
♥ Cells: introduction
11:19 PM
♥ DNA song
11:04 PM
♥ Element song
11:01 PM
Tuesday, August 10, 2010
♥ Ace project (Using Distillation to Make Pure Water)
8:14 AM
Thursday, August 5, 2010
♥ What Are CHROMOSOMES?
8:24 AM
Monday, August 2, 2010
♥ ACE PROJECT = Carbon (Solids)
Title: Carbon (Solid)
Slide 1: What Is An Allotropes?
From what I have researched on, I know that allotropes are compounds that exists in forms with different chemical structures. Some common examples are fullerene and carbon (diamond, graphite)
Slide 2: How to form diamonds
120km to 200km below our feet, diamonds are formed. Rocks in the upper mantle of the Earth melt due to high temperatures. The carbon from these rocks is forced lower into the earth where it finally condenses into new rock. If the temperature and pressure is just nice, the carbon will form diamonds. Then, the diamonds rises to the surface of the Earth.
Slide 3: How to form graphite
In graphite, the carbon atoms bond together in layers, with each layer being parallel to the next and previous one. These layers allow graphite to flake apart, like when you use a pencil to write on a piece of paper.
Slide 4: How to form fullerene
A fullerene is formed when “carbon containing materials are burned with limited oxygen”. The fullerene tube structure is often referred to as a nanotube.
Slide 5: Conclusion
Diamond-edged saws cut stone for masons. Graphite electrodes allow electricity to jump between them, creating light. Fullerene molecules preserved noble gas molecules; These noble gas molecules then give testimony to a meteor impact that occurred in millennia past. These are just some uses I got form the internet.
Slide 1: What Is An Allotropes?
From what I have researched on, I know that allotropes are compounds that exists in forms with different chemical structures. Some common examples are fullerene and carbon (diamond, graphite)
Slide 2: How to form diamonds
120km to 200km below our feet, diamonds are formed. Rocks in the upper mantle of the Earth melt due to high temperatures. The carbon from these rocks is forced lower into the earth where it finally condenses into new rock. If the temperature and pressure is just nice, the carbon will form diamonds. Then, the diamonds rises to the surface of the Earth.
Slide 3: How to form graphite
In graphite, the carbon atoms bond together in layers, with each layer being parallel to the next and previous one. These layers allow graphite to flake apart, like when you use a pencil to write on a piece of paper.
Slide 4: How to form fullerene
A fullerene is formed when “carbon containing materials are burned with limited oxygen”. The fullerene tube structure is often referred to as a nanotube.
Slide 5: Conclusion
Diamond-edged saws cut stone for masons. Graphite electrodes allow electricity to jump between them, creating light. Fullerene molecules preserved noble gas molecules; These noble gas molecules then give testimony to a meteor impact that occurred in millennia past. These are just some uses I got form the internet.
7:52 AM
Friday, May 28, 2010
♥ Term 2 reflection
This term was quite fun as the experiments mostly involved burning. This video above was an experiment on burning magnesium, which emitted a bright light during the heating. I have learnt how wrong measurements could result in disasters and how measurements played a part in our lives. The "Kinetic Particle Theory" was okay for me but not for the conversion of units. I found it difficult to convert a small unit into a big unit, especially length.
7:42 AM
Wednesday, May 26, 2010
♥ Separation Techniques(Chromatography)
CHROMATOGRAPHY
In paper chromatography, there are two factors which the movement of each substance in the mixture need to depends on.
The substances separated by chromatography do not have to be colored. Colorless substance can be made to show up by spraying the paper with a locating agent. Then reacts with each of the colorless substances in order to produce a colored product.
We often used chromatography to identify the substances in a mixture. It is commonly used in hospital. It help doctors to find out whether the patient has diabetes, if paper chromatography might fund out whether sugar is present in the patient's urine.
Chromatography can also used to identify different dyes used in food.
ADSORPTION
We called the solids which are able to attract other substances strongly and hold them on their surface ADSORBENTS.
In paper chromatography, there are two factors which the movement of each substance in the mixture need to depends on.
- The solubility of the substance in the solvent. The substance moves with the solvent easily if the substance is very soluble in the solvent.
- The adsorption of the substance on the filter paper. Some solids are able to attract other substance strongly and hold them on their surface. This is called ADSORPTION. The substance will not move with the solvent easily if the substance in the mixture is absorbed strongly by the filter paper.
The substances separated by chromatography do not have to be colored. Colorless substance can be made to show up by spraying the paper with a locating agent. Then reacts with each of the colorless substances in order to produce a colored product.
We often used chromatography to identify the substances in a mixture. It is commonly used in hospital. It help doctors to find out whether the patient has diabetes, if paper chromatography might fund out whether sugar is present in the patient's urine.
Chromatography can also used to identify different dyes used in food.
ADSORPTION
We called the solids which are able to attract other substances strongly and hold them on their surface ADSORBENTS.
8:54 AM
♥ Separation Techniques(Fractional Distillation)
FRACTIONAL DISTILLATION
Miscible liquids are much more difficult to separate. Mixtures of miscible liquids can be separated by fractional distillation. It will provide the boiling points of the liquids are not too close.
If we want to separate a mixture of ethanol and water. The diagram below is suitable for this process. The fractionating column is packed with glass bead. It provides a large surface area for vaporization and condensation of the liquid mixture.
Ethanol is more volatile than water, since it has a lower boiling point (78oC). The vapor rises up the fractionating column when the mixture is heated. Because ethanol is more volatile, the vapor contains more ethanol. The hot vapor condenses upon touching the cold glass beads. There is a continuos rise of hot vapor up the fractionating column at the same time. Hot vapor will make the condensed vapor boils again. It will contain more and more ethanol as the vapor rises up to the fractionating column.
The above process is to be repeated many times before the vapor consists only pure ethanol. During the process the escaping vapor is measured by a thermometer of the fractionating column. The temperature will remain steady for some time and will then rise quickly and become pure ethanol.
When the ethanol has boiled off completely, the escaping vapor will consist of pure water only .
Generally, for fractional distillation to work best,the difference in boiling points of liquids in the mixture should be greater than 10C. The separation will not be complete if it is not.
8:52 AM
♥ Separation Techniques(Distillation)
DISTILLATION
When a solution of solid in liquid is heated, the liquid will evaporates. The hot vapor that formed can de condensed back to liquid again on a cold surface. We called this method DISTILLATION. Distillation is used for separating a solvent from a solution. We called the liquid collected a distillate.
Evaporation + Condensation = DISTILLATION
A way is to recover water from a salt solution. The solution is heated and the stream is to be condensed back to water. The solute and solvent can both be collected.
Before heating, there are a few very small pieces of pumice stone (antibumping granules) added into the solution. This is used to ensure even boiling. Otherwise, the solution might become so vigorously agitated which some of it might spurt into the collecting vessel before vaporization.
The bulb of the thermometer is to be placed above the liquid surface. In order to record the temperature of the vapor distilled over and collected. In this case, it will provide the boiling point.
Another set-up for distillation uses a condenser. This set-up condenses the steam even more efficiently. The condenser consists of two tubes, one inside the other. Cool water will pass through the outer tube and steam from the solution will pass through the inner tube.
The water supply enters the condenser at the lower opening, leaving the upper opening to get a better cooling effect.
When a solution of solid in liquid is heated, the liquid will evaporates. The hot vapor that formed can de condensed back to liquid again on a cold surface. We called this method DISTILLATION. Distillation is used for separating a solvent from a solution. We called the liquid collected a distillate.
Evaporation + Condensation = DISTILLATION
A way is to recover water from a salt solution. The solution is heated and the stream is to be condensed back to water. The solute and solvent can both be collected.
Before heating, there are a few very small pieces of pumice stone (antibumping granules) added into the solution. This is used to ensure even boiling. Otherwise, the solution might become so vigorously agitated which some of it might spurt into the collecting vessel before vaporization.
The bulb of the thermometer is to be placed above the liquid surface. In order to record the temperature of the vapor distilled over and collected. In this case, it will provide the boiling point.
Another set-up for distillation uses a condenser. This set-up condenses the steam even more efficiently. The condenser consists of two tubes, one inside the other. Cool water will pass through the outer tube and steam from the solution will pass through the inner tube.
The water supply enters the condenser at the lower opening, leaving the upper opening to get a better cooling effect.
8:46 AM
♥ Separation Techniques(Crystallisation)
CRYSTALLIZATION
It is a process of forming crystals. It is also a method for separating dissolved solids from a solution.
Two common techniques of Crystallization are:
It is a process of forming crystals. It is also a method for separating dissolved solids from a solution.
Two common techniques of Crystallization are:
- By cooling down a hot concentrated solution.
The solution has to be heated to get rid of some water in order to obtain crystals from an unsaturated aqueous solution. The solution becomes more concentrated as the water boils away. The solvent cannot hold all the dissolved solids when concentrated solution is cools and is hot. The reason for this is because a hot solvent dissolve more solutes than cold solvent. Then the extra solids will be separated out as crystals.
We can check the solution is concentrated enough by placing one drop of it on a microscopic slide by using a glass rod. If the solution is concentrated enough, crystals should form. - Slow evaporation of solution at room temperature.
Crystals can be obtained by evaporating a solution at room temperature. After the solvent in the solution has been evaporates, the remaining solution will becomes more and more concentrated. Then it will becomes saturated. Further evaporation makes the extra solids separate out as crystals. It may take several days or maybe even weeks for crystals to form because evaporation of a solution at room temperature is a slow process. Note that the beaker is covered with a piece of filter paper with holes on it in the below diagram. The used of the filter paper is to prevent dust and dirt from getting into the solution. Otherwise the crystals formed might be very small. Crystals formed by slow cooling or evaporation are large. For those which formed quickly are usually small. It is because solute particle need time to arrange themselves in regular shapes in order to form crystals.After crystallization, crystals can then be separated from the solution by using filtration. Use cold distilled water to wash the crystals two or three times after filtration. Collect the crystals with a spatula and dry them by pressing it gently between filter papers.
8:30 AM
♥ Separation Techniques(Evaporation)
We cannot separate a mixture which is a solution using filtration or centrifugation. Since it is spread all through the solvent in tiny particles. The solution is heated so that the solvent evaporates, and just leave the solid behind. The diagram below show by using this method, salt can be obtained from its solution. Only solute can be obtained, and solvent will evaporate away in the process of EVAPORATION.
8:22 AM
♥ Separation Techniques(Filtration)
FILTRATION
This is a method which is the most especially effective for separating suspensions, for example mud in water. We pour the mixture into a funnel fitted with a piece of filter paper. There are tiny holes in the filter paper for the liquid to pass through, the solid particles are too large to do so, therefore the solid particles will stay on the paper as what we called a solid residue. We called the liquid which pass through the FILTRATE.
There are two ways of folding the filter paper for the filtration:
There are two ways of folding the filter paper for the filtration:
- Fold the paper in half along one diameter then in quarters.
- Fold a fluted filter paper. Fold the paper in half, then open out, after that fold in the same director at a right angles to the original. Fold the paper two more times, the folds being all the same direction and mutually at around 45 degrees. Each section will then individually folded in the opposite direction. As result is a 'FLUTED' which sixteen faces will be produced. It provide a faster rate of filtration.
7:56 AM
Tuesday, March 30, 2010
♥ Kinetic Particle Theory
Matter is anything that occupies space and has mass. Matter can exist in 3 physical states : solid, liquid and gaseous, depending on the temperature and pressure of their surroundings. Solids, liquids and gases have different properties as all matter is made up of a large amount of tiny particles which are always in constant random motion.
Using the kinetic particle theory to explain what happens to the particles in a solid when it is heated until it melts
When a solid is heated, the particles absorb heat energy. The particles gain kinetic energy and start to vibrate faster. At a certain temperature known as the melting point, the particles have enough kinetic energy to overcome the strong forces of attraction holding the particles together in the solid. The particles start to break away from one another and the solid becomes a liquid.
Using the kinetic particle theory to explain what happens to the particles in a solid when it is heated until it melts
When a solid is heated, the particles absorb heat energy. The particles gain kinetic energy and start to vibrate faster. At a certain temperature known as the melting point, the particles have enough kinetic energy to overcome the strong forces of attraction holding the particles together in the solid. The particles start to break away from one another and the solid becomes a liquid.
7:01 AM
Friday, March 12, 2010
♥ Term 1 reflections
After this term, I managed to learn many interesting things and had a lot of enriching experiences in the science laboratory. I did pretty well for this term's test so I shall strive for better results. Science is all about inquiry, so the first chapter for Science is " Science as an Inquiry". These are the basics and that is good as if I cannot get my basics correct, how will I strive for better results.
6:20 AM
Monday, March 8, 2010
♥ Dinosaurs being wiped out
Wow! After so many years of research, they have finally solve the mystery of the extinction of dinosaurs! From what they say, dinosaurs were wiped out by an asteroid the size of the Isle of Wight that hit the Earth with the explosive power of a billion atom bombs. Can you imagine a billion ATOMIC BOMBS? At that time, I don't think there were any bomb shelters, even if there were, they would still be wiped out. The impact is just too huge. It could wipe us all out....The giant space rock, measuring around 15 kilometres across, slammed into the Earth at Chicxulub, off the Yucatan peninsular. It would have caused fire storms and earthquakes, and blasted material high into the atmosphere, blocking out the Sun's light and heat to trigger a "nuclear winter" that would have killed off much of the Earth's life in a matter of days. Now, after knowing how the dinosaurs have been killed, I feel sad for them...... Interesting! Isn't it? If you want to see the asteroid hitting Earth, visit http://www.youtube.com/watch?v=GOcey9NxMF0&feature=related Though there are some humans, the animation is awesome!
IT HAPPENED BEFORE............WILL IT HAPPEN AGAIN????
7:33 AM
Thursday, March 4, 2010
♥ Mass vs Weight; Density
Properties of Mass :
Properties of Weight: :
- The amount of matter in a body
- A physical property of the object that does not change
- SI Unit : kilogram ( kg )
- Measured using an electronic balance or beam balance
Properties of Weight: :
- The amount of gravitational force on a body
- Will vary according to the gravitational force
- SI Unit : Newton ( N )
- Measured using a spring balance
3:16 AM
Sunday, February 28, 2010
♥ REFLECTION ON DENSITY
Why and How Did the Density Of The water change when salt was added?
Ans: It raises the density by adding more mass, to the same volume of water. Adding salt to one cup of water will raise the density because the salt is adding mass to the same amount of volume of the cup of water. Salt increases the density of water. Pure water density: 1000 kg/m3 Salt water density: 1027 kg/m3 (at sea surface)
Now, try to explain why the egg sunk in salt water but not tap water
Ans: The density of the egg is higher than the density of tap water, so it sinks. Adding salt to the water increases the density of the water, because the salt increases the mass without changing the volume very much. With enough added salt, the saltwater solution density is higher than the egg's, and the egg will then float.
Ans: It raises the density by adding more mass, to the same volume of water. Adding salt to one cup of water will raise the density because the salt is adding mass to the same amount of volume of the cup of water. Salt increases the density of water. Pure water density: 1000 kg/m3 Salt water density: 1027 kg/m3 (at sea surface)
Now, try to explain why the egg sunk in salt water but not tap water
Ans: The density of the egg is higher than the density of tap water, so it sinks. Adding salt to the water increases the density of the water, because the salt increases the mass without changing the volume very much. With enough added salt, the saltwater solution density is higher than the egg's, and the egg will then float.
5:26 PM
Saturday, February 13, 2010
♥ Units and measurements
Without a widely accepted system of units of measurement our civilization could not exist. Imagine the chaos if there were no standards for the measurement of mass, length and time, for example.
Scientists identify quantities which describe the natural world. In order to decide how much of a particular quantity a given object has, for example, MASS, it is necessary to compare that object to the masses of other objects which have known masses, defined in terms of an agreed standard.
A unit is an established standard for a physical quantity against which particular examples of that physical quantity can be compared. The act of comparing a physical quantity to a unit is called MEASUREMENT and the MEASURE of a particular physical quantity is the ratio of that physical quantity to the unit. The measure is a numerical value. When we calculate, we manipulate the measure, not the physical quantity.
Scientists identify quantities which describe the natural world. In order to decide how much of a particular quantity a given object has, for example, MASS, it is necessary to compare that object to the masses of other objects which have known masses, defined in terms of an agreed standard.
The instrument used is called a BALANCE, shown above. A PHYSICAL QUANTITY can be defined in terms of the operations necessary to measure it. For example, the length of an object can be determined by comparing it to an object of known length, such as a ruler.
A unit is an established standard for a physical quantity against which particular examples of that physical quantity can be compared. The act of comparing a physical quantity to a unit is called MEASUREMENT and the MEASURE of a particular physical quantity is the ratio of that physical quantity to the unit. The measure is a numerical value. When we calculate, we manipulate the measure, not the physical quantity.5:45 PM
Friday, January 15, 2010
♥ Safety in The Lab
12:07 AM
