- January
1P7
(Determining Density)
Apparatus: Micrometer screw gauge, Small plastic bottle, Electronic beam balance, 5 glass marbles.
Putting the glass stopper in the measuring cylinder.
Measuring the diameter of the marble with a micrometer screw gauge.Weighing the mass of the marbles and the plastic bottles using an electronic weighing scale.
This activity once again stressed that results may not be consistent, thus the average reading is the most accurate. The reason for using 5 marbles instead of 1 marbles is to take the average reading of the 5 marbles as the diameter and the mass of the marbles may not be consistent. It also tells me two precautions that I must take when using the measuring cylinder. It is to avoid parallax error while reading the marking by placing the eye vertically to the marking. To obtain the correct volume, the bottom part of the meniscus is to be read as the liquid in the measuring cylinder is water. I liked measuring the volume of the water and the glass stopper. Reading the meniscus is my favorite part. However, what i dislike most is reading the diameter of the glass marble as I feel that it was very troublesome to take the two readings of the same marble. This experiment was done by myself.
-11.05.2012
1P9
(Investigating Mixtures and Compounds)
Aim: To investigate the properties of a mixture and a compound.
Apparatus: Tripod stand, Evaporating dish, Glass rod, Wire gauze, Bunsen burner.
Materials: Sulphur powder, Iron filings, Filter paper, a piece of Paper magnet.
In this experiment, I learnt a lot about compounds, mixture and elements. I learnt that a compound is a substance containing two or more elements joined together by a chemical reaction. It has different properties from its elements. On the other hand, a mixture can be separated into its elements by physical methods and has the properties of its constituent elements. An element is a substance that cannot be broken down into simpler substances by any known chemicals.
I do not like putting the magnet near the mixture of sulphur powder and iron filings to test for its magnetic properties as removing the iron filings is a very troublesome job. Trying to remove the iron filings that were stubbornly attracted to the magnet took a long time. However, I like the part where we get to heat the mixture of iron filings and sulphur powder to form a compound. I have always love heating. I excites me to see what is the product after heating the mixture. This experiment was done by both my partner and myself. We had a lot of fun doing the experiment together.
1P10
(Forming Compounds)
Aim: To investigate the formation of compounds by-
1) Reacting two elements
2) Reacting an element and compound
3) Reacting two compounds
Materials: Magnesium ribbon, Iron filings, Dilute sulphuric acid, Lead(II) nitrate solution, Sodium chloride
Apparatus: Test-tube, Bunsen burner, Evaporating dish, Test-tube holder, Pair of tongs.
Reacting two elements:
Heating magnesium and oxygen gives magnesium oxide.
Reacting an element with a compound:
Putting Iron and Sulphuric acid together gives Iron sulphate and Hydrogen gas.
Reacting two compounds:
Mixing Lead(II) nitrate and Sodium chloride gives Lead(II) chloride and Sodium nitrate.
What I like most about this experiment is the heating of the magnesium ribbon. It was very exciting and spectacular to see the magnesium ribbon burning with the bright white light. Both my partner and I were amazed when we saw it. What me and my partner dislike was the mixing of Lead(II) nitrate solution with Sodium chloride solution. There was nothing fun and exciting about this, as the only step that was needed was to add Lead(II) nitrate solution into the Sodium chloride solution and to observe the white precipitate form in the colourless solution.
-13.04.2012
1P11
(Which can dissolve more)
Aim: To find out if the solubility of different solutes differ in the same solvent
In this experiment, since we want to find the solubility of different solutes, the factor we should change is the type of solute.
Factors that are to be kept constant:
1) Type of solvent
2) Temperature of solvent
3) Amount of solvent
From this experiment, we can infer that among Baking Soda, Iodine Crystals and Salt, Salt is most soluble in water, while Iodine Crystals is the least soluble.
I learnt that, to improve the experiment to find the solubility of different solutes in a solvent more accurately, we can:
1) Find an estimated amount of solute that will dissolve by adding in large amounts (1.0g each time).
2) Perform the experiment a second time, but add in smaller amounts (0.5g each time) of the solute when the amount added is close to the estimated obtained earlier.
Finally, and most importantly, I learnt that the solubility of different solutes in the same solvent is different.
Here are some cool facts for you:
Water is known as the universal solvent and it is very important for sustaining life. The longest time that anyone has lived without food and water is 18 days. An 18 year-old man in Austria was put into a police cell on the 1st April 1979, and forgotten! When he was discovered on 18th April, he was extremely close to death.
-25.04.2012
1P12
(A Separation Problem)
Aim: To separate a mixture of Iron filings, Styrofoam beads, Salt and Sand.
Laboratory equipment: Beakers, Filter funnel, Glass rod, Evaporating dish, Tripod stand, Wire Gauze, Bunsen burner, Retort stand, Magnet.
Steps involved:
1) To separate iron filings from the mixture using a magnet.
2) To separate Styrofoam beads from the mixture by adding water and removing it by hand.
3) To separate sand from the mixture using filtration.
4) To separate salt from the mixture using heating.
From this experiment, I learnt that some items can be easily separated by using our knowledge about them. For example, we have the knowledge that iron filings are attracted to magnets. Using this knowledge on the experiment, we can easily separate the iron filings from the mixture using a magnet.
The part I liked most was the whole procedure of separating the objects from the mixture, as it gives me some sense of accomplishment. The part I dislike most was waiting for the Salt solution to be filtered out as it took quite some time. Overall, my partner and I enjoyed this lab session.
-26.04.2012
1P13
(Who Wrote the Secret Message?)
Apparatus and Materials: Boiling tube, Retort stand, Chromatography paper (15cm x 2 cm), Split cock, 3 x different brands of black ink, Ethanol and Water mixture.
One of the three brands on black ink, was used to write a message and the ink was extracted and chromatography was used to detect the colour components of the black ink. Chromatography was used on the three brands of black ink, Brand A, Brand B and Brand C to detect the colour components of each ink and would be observed to see which of the colour components matches the one that is used to write the message.
Steps include:
1) On one end of the chromatography paper, mark an ink spot.
2) Place the strip of chromatography paper between the two pieces of the Split cork.
3) Fill the boiling tube with the ethanol and water mixture to a depth of about 2 cm.
4) Lower the strip of chromatography paper into the boiling tube. Make sure that the ink spot is just above the liquid level in the tube.
The colours found in the ink of:
Brand A- Black, Purple
Brand B- Black, Pink, Blue
Brand C- Yellow, Pink, Purple, Blue, Orange
From the results, it is concluded that the ink from Brand B is used to write the secret message.
I liked watching the ink spread into its different colour components. It looks extremely beautiful. However, waiting for the colour to spread was not too pleasant as it took quite a long time.
I also learnt that chromatography can be used to find out the colours in food such as coloured chocolate candies.
-03.07.2012
1P14
(Inside of cells)
Apparatus: Microscope, Slide, Cover slip, Dropper, Mounted needle, Pair of forceps
Materials: Filter paper, Clean toothpick, Dilute Iodine solution, Fresh onion
Part A (Inside an animal cell):
Gently scrape some cells from the inside of your cheek with a clean toothpick. Spread the scrapings onto the drop of iodine on the slide. Place one side of a cover slip close to the drop of iodine solution while supporting the other side of the cover slip with a mounted needle. Gently and slowly lower the cover slip into the scrapings. Examine the specimen slide with a microscope. It can be observed that the cheek cell contains Cytoplasm, Cell membrane and Nucleus.
Part B (Inside a plant cell):
Place the piece of onion skin on a slide. Add a drop of dilute iodine solution onto the onion skin. Gently and slowly lower a cover slip onto the onion skin. Examine the specimen slide with a microscope. It can be observed that the onion cell contains Cytoplasm, Cell wall, Cell membrane and Nucleus.
A picture of the onion cell.
I learnt that iodine solution has to be used to stain the cell for a contrasting view. I also learnt that each type of cell in a multi-cellular organism specializes in performing one particular function known as division of labour. The advantage of division of labour is that every individual cell does not have to do everything needed for a proper functioning.
The part I like the most would be seeing the cells. Being able to use the microscope to see the cells have been a dream of mine since Primary school. Now, I finally get to touch a microscope and see a cell through it.
The part I dislike most would be trying to observe the cell under the microscope. My eyes just cannot seem to look at the cell for a long duration. After a while, my eye loses its focus on the cell and I have to look away and look into the lens again to see the cell.
-10.07.2012
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