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Bacteria and Disinfectants
Purpose: How concentration can affect the performance rate of disinfectants in killing micro-organisms.
Research:
"Chloroxylenol, also known as para-chloro-meta-xylenol (PCMX), is an antiseptic and disinfectant which is used for skin disinfection and cleaning surgical instruments.It is also used within a number of household disinfectants and wound cleaner. It is less effective than some other available agents.It is available as a liquid." https://en.wikipedia.org/wiki/Chloroxylenol
PRACTICE EXPERIMENT
Aim: I want to investigate how the concentration of Savlon affects the growth of bacteria.
Hypothesis: I predict that if the concentration of the Savlon is higher, then it will have a greater effect on the bacteria's growth, because
Equipment:
SAVLON EXPERIMENT
How different disinfectant concentrations can affect the growth and reproduction of micro-organisms.
PRACTICE EXPERIMENT
Aim: I want to investigate how the concentration of Savlon affects the growth of bacteria.
Hypothesis: I predict that if the concentration of the Savlon is higher, then it will have a greater effect on the bacteria's growth, because
Equipment:
- Agar plate
- Permanent marker
- Savlon
- Filter paper
- Hole punch
- Bacteria (yoghurt)
- Beaker
- Plastic pipette
- Spotting tile
- Tweezers
- Get an agar plate and mark it with a permanent marker into 4 sections.
- Dip a cotton bud into a beaker of yoghurt and spread it evenly across the agar plate.
- Use your plastic pipette to drop 10 drops of Savlon into one section of your spotting tile. Then add 9 drops of water into 3 other sections(A,B,C) on the spotting tile. In section A (1:10 dilution), add one drop of the Savlon then mix. Next add one drop from section A into section B(1:100 dilution) then mix. Finally, add one drop of section B into section C(1:1000 dilution) then mix.
- Hole punch 4 small discs of filter paper.
- Sterilize your tweezers by dipping them into a jar of ethanol (make sure you put the lid back on after use) then put the tweezers through the flame of the Bunsen burner
- Pick up a piece of your hole punched filter paper with your tweezers and soak it in water, then place it in the centre of the first section of your agar plate - this will be your control.
- For each of the 3 dilutions (1:10, 1:100, 1:1000), soak a hole punched filter paper in each one. Then place the filter papers separately in the other sections of the agar plate.
- Sellotape the agar plate shut and lay it upside down on a windowsill overnight.
Results:
Quadrant
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Measurement of clear zone (mm)
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1
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2 mm
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2
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3 mm
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3
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9 mm
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4
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10 mm
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Planning Sheet Student name:Amber
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2. FAIR TEST
Which variable will be changed? (This is the independent variable)
The variable that will be changed will be the concentration of the Savlon.
How will the independent variable be changed?
The variable will be changed by putting 9 drops of water into 3 slots on the spotting tile then one drop of 100% Savlon will be mixed into the first slot, then a drop from the first slot will be fixed into the second slot, then a drop from the second slot will be mixed into the third slot.
Give a suitable range of values for this variable
The variable will have concentrations of 0%,0.1%,1% and 10%
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3. FAIR TEST
Which variable will have to be measured or observed in order to get some data or information from the investigation? (This is the dependent variable)
The variable that we will measure in this experiment will be the clear zones around the bacteria.The measurement of the clear zone will be determined by the level of concentration on the filter paper.
How will the dependent variable be measured or observed?
We can measure the clear zone with a ruler. We will start measuring from the edge of the filter paper disc out to the end of the clear zone. Our measurements will be in mm.
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Other variables
|
Describe how this variable will be controlled or kept the same.
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Tempurature
| All three agar plates will be put into an incubator, therefore making sure they are all at the same temperature. A different temperature for any of the plates would deem the test unfair. |
| Size of the disk holding the Savlon | We will keep the size of the disks the same by using the same hole punch to get all of the necessary disks for our experiment. If the disks are different sizes then they will all absorb different amounts of the solutions, making the test unfair. |
| Type of disinfectant | We will have to make sure that the disinfectant we use is the same throughout the whole experiment. Initially, we were going to use Dettol but we swapped to Savlon as it had a good impact in our practice experiment. |
We will ensure that our results are reliable by completing the exact same experiment in three separate agar plates, making sure each test is done the same so it is a fair test.
| |
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SAVLON EXPERIMENT
How different disinfectant concentrations can affect the growth and reproduction of micro-organisms.
Aim: I want to investigate how the concentration of Savlon affects the growth and reproduction of bacteria.
Hypothesis: I predict that if the concentration of the Savlon is high then it will have a greater effect on the growth and reproduction of bacteria because Savlon is used to prevent the growth of unwanted bacteria. If there is less growth of bacteria then the clear zone will be bigger.
Variables:
Independent variable: The variable that will be changed will be the concentration of the Savlon. This will be our independent variable.The variable will be changed by putting 9 drops of water into 3 slots on the spotting tile then one drop of 100% Savlon will be mixed into the first slot, then a drop from the first slot will be fixed into the second slot, then a drop from the second slot will be mixed into the third slot. Ultimately the variable will have concentrations of 0%,0.1%,1% and 10%.
Dependent variable: The variable that we will measure in this experiment will be the clear zones around the bacteria.The clear zone is our dependent variable and will be dependent on the independent variable.The measurement of the clear zone will be determined by the level of concentration on the filter paper. We can measure the clear zone with a ruler. We will start measuring from the edge of the filter paper disc out to the end of the clear zone. Our measurements will be in mm.
We will ensure that our results are reliable by completing the exact same experiment in three separate agar plates to see if there is consistency with our results. We will make sure the temperature is the same by putting all three agar plates in an incubator, ensuring they are the same temperature. If the temperature is too hot or too cold it could affect our results.The size of the disks holding the Savlon will also have to remain the same throughout all three experiments, we'll ensure this by using the same hole punch to acquire all the disks we need. Our type of disinfectant will also need to remain the same throughout all the experiments or else if we change to a different disinfectant we would get completely different and unreliavle results, because the ingredients would all be different.
Equipment:
Results:
Conclusion: I predicted that if the concentration of the Savlon was higher then it would have a greater effect on the growth and reproduction of bacteria and the clear zone around the filter paper disc would be larger. From my graph, I can see an increasing trend. I conclude that the higher the concentration of the Savlon the more effective it will be at preventing the growth and reproduction of bacteria and result in a larger clear zone around the disk.
EXPLAINING:
Discussion:
Bacteria is a gel-like matrix consisting of nutrients, water, enzymes, wastes and gases. Bacteria have a cellular structure as seen in the image above. The outer layer of the bacterial cell is called the capsule and protects the cell. The cell wall is between the capsule and the cell membrane. The cell wall gives the cell its shape and protects the cell contents. The cell membrane controls what enters and exits the cell, nutrition and excretion. Pili are located around the capsule and are used to attach to other bacterial cells and exchange genetic information, which is called conjugation. The flagellum is known as the 'tail', it is used for movement. Plasmids are circular bits of DNA which code for nonessential characteristics. Cytoplasm is the 'soup' of the cell which holds the DNA. Ribosomes are found inside the cell and are where proteins are made. The nucleoid floats in the cytoplasm and contains DNA. It may also contain RNA, proteins and enzymes. MRS GREN is an acronym that stands for movement, respiration, sensitivity, growth, excretion and nutrition. Bacteria use these necessary features to live. In our experiment, we mainly aimed our attention at the bacteria's growth, reproduction and nutrition. Bacteria can reproduce very quickly through binary fission, a form of asexual reproduction. This is where new cells are produced which are genetically identical to the parent cell, they are known as clones. Although the offspring are identical to the parent cell, they could have mutations (occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene) within their DNA. In the image to the left, you can see the process of Binary Fission. The DNA replicates and the cytoplasm pinches off and new cell walls are created. Two identical daughter cells are produced. Every time the cell grows it is reproducing. As bacteria reproduce their numbers build up very quickly, which can lead to a competition between bacteria for resources such as nutrients. Bacteria need nutrients for energy to grow and other cell processes. Nutrition is where bacteria secrete (produce and discharge) enzymes onto their food. The enzymes then digest the food and it is absorbed into the bacterial cell by diffusion (passive movement of molecules through an area of higher concentration to an area of lower concentration).
The purpose of this investigation was to see what affect disinfectants and different concentrations of them had on microorganisms. Disinfectants are antimicrobial agents that are used to eradicate microorganisms living on the surface of non-living objects. Disinfectants destroy microorganisms by destroying the cell membrane (which has control over nutrition and excretion) or by interfering with the metabolism. Savlon is a disinfectant that can also be used on living organisms, it's an antiseptic. Savlon can reduce the possibility of infections from a wound. Savlon is a combination of the antiseptics, Cetrimide(C16H33)N(CH3)3 and Chlorhexidine C22H30Cl2N10. Cetrimide contains a mixture of ammonium salts. Cetrimide works by rupturing the cell membrane which controls what enters and exits the cell, it breaks apart the bacteria. Chlorhexidine is both a disinfectant and antiseptic. It is a broad spectrum bactericide, meaning it can kill a wide range of bacteria. Chlorhexidine kills microorganisms at a faster rate than other antimicrobials. Chlorhexidine works by killing enzymes, which are used for growth, reproduction, creating energy, and are often excreted (discharged from the microorganism) outside their cell walls.The Savlon in our experiment had a combination of 0.3% of Chlorhexidine and 3.0% of Cetrimide. Chlorhexidine and Cetrimide hinder the bacteria by oxidizing (adding oxygen or removing hydrogen from the molecule) the molecules on the surface of the bacteria, thus disrupting the cell wall and cell membrane and irreversibly harming the proteins on the surface, causing to stop the enzymes in the nucleoid to work accordingly. Cell lysis subsists of a disruption to the cell membrane in a bacterial cell. The cell membrane is where molecules are transported in and out of the cell. It keeps concentration gradients (the process of particles moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles. The areas are separated by the cell membrane) which is very important as it helps the cell survive. So if the cell membrane is disrupted the cell will no longer be able to survive, because it will no longer be able to acquire the nutrients it needs. I can see from my graph that there is an increasing trend. When the concentration of the Savlon was higher the clear zone around the disc was larger. I can, therefore, conclude that I have proved my hypothesis correct, as the clear zone is larger when the concentration of the Savlon is higher.
Evaluation:
I believe that this experiment was reliable as we completed the exact same experiment 3 times and saw similar results for the measurements of the clear zones throughout each one. We were initially going to use Dettol as our disinfectant for our experiment, but we switched to Savlon as it worked rather well in our practice experiment. Another thing we changed was the application of the yoghurt. Originally in the practice experiment, we just smeared the yoghurt onto the agar plate with a cotton bud, but we decided to dilute (make a liquid thinner or weaker by adding water or another solvent to it) the yoghurt so we could just pour it onto the agar plates and remove the excess liquid. This helped a lot because the yoghurt was spread out more evenly and there were no smear marks. If I were to do this experiment again I would like to use a larger agar plate so that I could clearly see the whole clear zone around each disc, since some of the clear zones joined together in our experiment. I found this investigation very interesting. I learned a lot about bacteria and how they are structured and how they work. I also learned a lot about disinfectants and what exactly they do. I learnt about the ingredients in Savlon and how they are effective at killing bacteria. I don't think I have any further questions at this point. ______________________________________________________________________________
Thursday, 25 May 2017Independent variable: The variable that will be changed will be the concentration of the Savlon. This will be our independent variable.The variable will be changed by putting 9 drops of water into 3 slots on the spotting tile then one drop of 100% Savlon will be mixed into the first slot, then a drop from the first slot will be fixed into the second slot, then a drop from the second slot will be mixed into the third slot. Ultimately the variable will have concentrations of 0%,0.1%,1% and 10%.
Dependent variable: The variable that we will measure in this experiment will be the clear zones around the bacteria.The clear zone is our dependent variable and will be dependent on the independent variable.The measurement of the clear zone will be determined by the level of concentration on the filter paper. We can measure the clear zone with a ruler. We will start measuring from the edge of the filter paper disc out to the end of the clear zone. Our measurements will be in mm.
We will ensure that our results are reliable by completing the exact same experiment in three separate agar plates to see if there is consistency with our results. We will make sure the temperature is the same by putting all three agar plates in an incubator, ensuring they are the same temperature. If the temperature is too hot or too cold it could affect our results.The size of the disks holding the Savlon will also have to remain the same throughout all three experiments, we'll ensure this by using the same hole punch to acquire all the disks we need. Our type of disinfectant will also need to remain the same throughout all the experiments or else if we change to a different disinfectant we would get completely different and unreliavle results, because the ingredients would all be different.
Equipment:
- Three Agar plates
- Permanent marker
- Dettol
- Filter paper
- Hole punch
- Bacteria (yoghurt)
- Beaker
- Plastic pipette
- Spotting tile
- Tweezers
- Bunsen burner
- Ruler
Method:
- Get your equipment.
- Acquire three agar plates and mark each one with your permanent marker into 4 quadrants.
- Pour diluted yoghurt into the 3 agar plates, remove excess fluid.
- Use your plastic pipette to drop 10 drops of Savlon into one section of your spotting tile. Then add 9 drops of water into 3 other sections(A,B,C) on the spotting tile. In section A (1:10 dilution), add one drop of the 100% Savlon then mix. Next add one drop from section A into section B(1:100 dilution) then mix. Finally, add one drop of section B into section C(1:1000 dilution) then mix.
- Hole punch filter paper into 4 small discs for each plate.
- Sterilize your tweezers by dipping them into a jar of ethanol (make sure you put the lid back on after use) then put the tweezers through the flame of the Bunsen burner
- Pick up a piece of your hole punched filter paper with your tweezers and soak it in water, then place it in the centre of the first section of your agar plate - this will be your control. Repeat this same step for all three of your agar plates.
- For each of the 3 dilutions (1:10, 1:100, 1:1000), soak a hole punched filter paper in each one. Then place the filter papers separately in the other sections of the agar plate. Repeat this for each of your agar plates.
- Sellotape the agar plates shut and lay them upside down in an incubator overnight.
Results:
Analysis:
Conclusion: I predicted that if the concentration of the Savlon was higher then it would have a greater effect on the growth and reproduction of bacteria and the clear zone around the filter paper disc would be larger. From my graph, I can see an increasing trend. I conclude that the higher the concentration of the Savlon the more effective it will be at preventing the growth and reproduction of bacteria and result in a larger clear zone around the disk.
EXPLAINING:
Discussion:
Bacteria is a gel-like matrix consisting of nutrients, water, enzymes, wastes and gases. Bacteria have a cellular structure as seen in the image above. The outer layer of the bacterial cell is called the capsule and protects the cell. The cell wall is between the capsule and the cell membrane. The cell wall gives the cell its shape and protects the cell contents. The cell membrane controls what enters and exits the cell, nutrition and excretion. Pili are located around the capsule and are used to attach to other bacterial cells and exchange genetic information, which is called conjugation. The flagellum is known as the 'tail', it is used for movement. Plasmids are circular bits of DNA which code for nonessential characteristics. Cytoplasm is the 'soup' of the cell which holds the DNA. Ribosomes are found inside the cell and are where proteins are made. The nucleoid floats in the cytoplasm and contains DNA. It may also contain RNA, proteins and enzymes. MRS GREN is an acronym that stands for movement, respiration, sensitivity, growth, excretion and nutrition. Bacteria use these necessary features to live. In our experiment, we mainly aimed our attention at the bacteria's growth, reproduction and nutrition. Bacteria can reproduce very quickly through binary fission, a form of asexual reproduction. This is where new cells are produced which are genetically identical to the parent cell, they are known as clones. Although the offspring are identical to the parent cell, they could have mutations (occurs when a DNA gene is damaged or changed in such a way as to alter the genetic message carried by that gene) within their DNA. In the image to the left, you can see the process of Binary Fission. The DNA replicates and the cytoplasm pinches off and new cell walls are created. Two identical daughter cells are produced. Every time the cell grows it is reproducing. As bacteria reproduce their numbers build up very quickly, which can lead to a competition between bacteria for resources such as nutrients. Bacteria need nutrients for energy to grow and other cell processes. Nutrition is where bacteria secrete (produce and discharge) enzymes onto their food. The enzymes then digest the food and it is absorbed into the bacterial cell by diffusion (passive movement of molecules through an area of higher concentration to an area of lower concentration).The purpose of this investigation was to see what affect disinfectants and different concentrations of them had on microorganisms. Disinfectants are antimicrobial agents that are used to eradicate microorganisms living on the surface of non-living objects. Disinfectants destroy microorganisms by destroying the cell membrane (which has control over nutrition and excretion) or by interfering with the metabolism. Savlon is a disinfectant that can also be used on living organisms, it's an antiseptic. Savlon can reduce the possibility of infections from a wound. Savlon is a combination of the antiseptics, Cetrimide(C16H33)N(CH3)3 and Chlorhexidine C22H30Cl2N10. Cetrimide contains a mixture of ammonium salts. Cetrimide works by rupturing the cell membrane which controls what enters and exits the cell, it breaks apart the bacteria. Chlorhexidine is both a disinfectant and antiseptic. It is a broad spectrum bactericide, meaning it can kill a wide range of bacteria. Chlorhexidine kills microorganisms at a faster rate than other antimicrobials. Chlorhexidine works by killing enzymes, which are used for growth, reproduction, creating energy, and are often excreted (discharged from the microorganism) outside their cell walls.The Savlon in our experiment had a combination of 0.3% of Chlorhexidine and 3.0% of Cetrimide. Chlorhexidine and Cetrimide hinder the bacteria by oxidizing (adding oxygen or removing hydrogen from the molecule) the molecules on the surface of the bacteria, thus disrupting the cell wall and cell membrane and irreversibly harming the proteins on the surface, causing to stop the enzymes in the nucleoid to work accordingly. Cell lysis subsists of a disruption to the cell membrane in a bacterial cell. The cell membrane is where molecules are transported in and out of the cell. It keeps concentration gradients (the process of particles moving through a solution or gas from an area with a higher number of particles to an area with a lower number of particles. The areas are separated by the cell membrane) which is very important as it helps the cell survive. So if the cell membrane is disrupted the cell will no longer be able to survive, because it will no longer be able to acquire the nutrients it needs. I can see from my graph that there is an increasing trend. When the concentration of the Savlon was higher the clear zone around the disc was larger. I can, therefore, conclude that I have proved my hypothesis correct, as the clear zone is larger when the concentration of the Savlon is higher.
Evaluation:
I believe that this experiment was reliable as we completed the exact same experiment 3 times and saw similar results for the measurements of the clear zones throughout each one. We were initially going to use Dettol as our disinfectant for our experiment, but we switched to Savlon as it worked rather well in our practice experiment. Another thing we changed was the application of the yoghurt. Originally in the practice experiment, we just smeared the yoghurt onto the agar plate with a cotton bud, but we decided to dilute (make a liquid thinner or weaker by adding water or another solvent to it) the yoghurt so we could just pour it onto the agar plates and remove the excess liquid. This helped a lot because the yoghurt was spread out more evenly and there were no smear marks. If I were to do this experiment again I would like to use a larger agar plate so that I could clearly see the whole clear zone around each disc, since some of the clear zones joined together in our experiment. I found this investigation very interesting. I learned a lot about bacteria and how they are structured and how they work. I also learned a lot about disinfectants and what exactly they do. I learnt about the ingredients in Savlon and how they are effective at killing bacteria. I don't think I have any further questions at this point. ______________________________________________________________________________
Experiment 4
Observing the Effect of a Catalyst on a Chemical Reaction Level 1 SciPad page 133
Aim: To observe the effects of a copper catalyst on the reaction between zinc and sulfuric acid.
Equipment:
- Three test tubes
- Test tube rack
- 10mL measuring cylinder
- Dropping pipette
- Granulated zinc
- Copper turnings or powder
- Dilute sulfuric acid (H2SO4)
Method:
- Add roughly the same mass of zinc to test tubes 1 and 3
- Add roughly the same mass of copper to test tubes 2 and 3
- Add 5mL of dilute sulfuric acid to test tube 1. Note the rate of production of gas bubbles
- Add 5mL of dilute sulfuric acid to test tube 2. Note the rate of production of gas bubbles
- Add 5mL of the acid to test tube 3. Note the rate of production of gas bubbles
Observations
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Test tube 1
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Test tube 2
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Test tube 3
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As we inserted the acid into the zinc it bubbled for a long time
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As we inserted the acid into the copper powder, not a lot happened
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As we inserted the acid into the copper and zinc, it bubbled faster than the first test tube
|
Conclusion:
Test tube 1 contained a normal reaction at its normal reaction rate with the acid and zinc. Test tube 3 had a way faster reaction rate than test tube 1, because the catalyst; copper, was added to the acid and zinc. The catalyst sped up the reaction between the acid and zinc, but the copper didn't chemically change it.
Wednesday, 24 May 2017
Experiment 3
Observing the Effects of Surface Area on Reaction Rate Level 1 SciPad page 130
Aim: To make simple observations during a reaction between calcium carbonate (CaCo3) chips and powder, with hydrochloric acid (HCl).
Equipment:
- Boiling tube
- Calcium carbonate chips and powder
- Hydrochloric acid
- Measuring cylinder
- Spatula
Method:
- Measure 2mL of hyrdrochloric acid and pour this into your boiling tube.
- Holding your boiling tube over a sink or heatproof mat, add a pea-sized amount of calcium carbonate powder to your boiling tube. Record your observations below.
Observations of powdered CaCo3:
As we dropped the calcium carbonate powder into the boiling tube of HCl, it fizzed for about 5 seconds then dissolved completely.
As we dropped the calcium carbonate powder into the boiling tube of HCl, it fizzed for about 5 seconds then dissolved completely.
3. Repeat the experiment, but this time use a chip of calcium carbonate that is roughly the same size as the spatula of powder you used previously. Record your observations below.
Observations of CaCo3 chip:
As we dropped the calcium carbonate chips into the boiling tube of HCl, it began to fizz, like the powder, although the chips fizzed for a much longer time than the powder, and took longer to dissolve.
As we dropped the calcium carbonate chips into the boiling tube of HCl, it began to fizz, like the powder, although the chips fizzed for a much longer time than the powder, and took longer to dissolve.
Conclusion:
The calcium carbonate powder reacted more quickly with the HCl than the calcium carbonate chips did. Since the size of the powder was smaller, the rate of reaction was faster, because it increases the surface area available for collisions to take place, it also increases the number of collisions.
Tuesday, 23 May 2017
Experiment 2
Investigating the Effect of the Concentration on Reaction Rate Level 1 SciPad page 128
Aim: I want to investigate how concentration effects the rate of reaction.
Equipment:
- Conical flask
- Measuring Cylinder
- Stopwatch
- Black cross on paper
- 0.2 mol L-1 sodium thiosulfate
- 1.0 mol L-1 hydrochlroic acid
Method:
- Put the 'X' paper on the bench mat, and put the conical flask on top of the paper
- Measure 10mL of sodium thiosulfate solution and put it into the conical flask
- Measure 40mL of water and put it into the conical flask, start the stopwatch, and swirl the flask. Time how long it takes for the cross to disappear;.
- Measure 5mL of acid. Pour the acid into the flask, start the stopwatch, and swirl the flask. Time how long it takes for the cross to disappear.
- Wash out the flask thoroughly. Repeat the experiment using the other volumes of sodium thiosulfate and water in the table on the right. Keep the volume of acid the same each time.
Results:
| Volume of sodium thiosulfate/ volume of water (mL) | Time (secs) |
| 10/40 | 224 |
| 20/30 | 78 |
| 30/20 | 57 |
| 40/10 | 42 |
| 50/0 | 33 |
Conclusion:
When the reactant particles have a higher concentration, successful collisions will be faster and happen more often.
__________________________________________________________________________________
Thursday, 18 May 2017
Experiment 1
Investigating the Effect of Temperature on Reaction Rate Level 1 SciPad page 126
Aim: I want to investigate how temperature effects the rate of reaction.
Equipment:
- Conical flask
- Beaker
- Measuring Cylinder
- Stopwatch
- Black cross on paper
- Water bath
- Thermometer
- 0.1 mol L-1 sodium thiosulfate
- 1.0 mol L-1 hydrochlroic acid
Method:
- Put the 'X' paper on the bench mat, and put the conical flask on top of the paper
- Measure 50mL of sodium thiosulfate solution and put it into the beaker
- Record the temperature of the sodium thiosulfate
- Measure 5mL of HCl and pour this into the conical flask
- Pour the sodium thiosulfate into the conical flask, start the stopwatch and swirl the flask. Time how long it takes for the cross to disappear when viewed from above (i.e. look down the mouth of the conical flask).
- Wash out the flask thoroughly.
- Repeat the experiment, sing a water bath to heat the sodium thiosulfate to 30°C, then 40°C and finally 50°C. Keep the volume of acid the same each time.
Results:
18°C 22 s
30°C 15 s
40°C 10 s
50°C 9.16 s
Conclusion:
For a successful collision to occur there needs to be sufficient energy and the correct orientation between particles. As you increase the temperature of the Sodium thiosulfate, there will be a higher chance of collisions and collisions happening more often, the faster it will react with the hydrochloric acid.
TUESDAY, 11 APRIL 2017
Science Assessment
Task B:
Gather Secondary Data
Report Sheet 1 What is Internal Reflection?
Source 1) Write URL, book or magazine:
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Information from Source 1) (copy and paste from website, book or magazine)
Waves going from a dense medium to a less dense medium speed up at the boundary. This causes light rays to bend when they pass from glass to air at an angle other than 90º. This is refraction.
Beyond a certain angle, called the critical angle, all the waves reflect back into the glass. We say that they are totally internally reflected.
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Key words from Source 1
dense, medium, speed up, boundary, light rays, bend, critical angle, waves,
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In your own words summarise relevant information from website, book or magazine
Internal reflection occurs when the angle of incidence is greater than the critical angle, all the waves are reflecting back into the medium.
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Report Sheet 2 How internal reflection is used in everyday life?
Source 1) Write URL, book or magazine:
|
Information from Source 1) (copy and paste from website, book or magazine)
Fiber optic cables carry communication signals using pulses of light generated by small lasers or light-emitting diodes (LEDs).
The cable consists of one or more strands of glass, each only slightly thicker than a human hair. The center of each strand is called the core, which provides the pathway for light to travel. The core is surrounded by a layer of glass called cladding that reflects light inward to avoid loss of signal and allow the light to pass through bends in the cable.
The two primary types of fiber cables are called single mode and multi mode fiber. Single mode fiber uses very thin glass strands and a laser to generate light while multi mode fibers use LEDs.
Single mode fiber networks often use Wave Division Multiplexing (WDM) techniques to increase the amount of data traffic that can be sent across the strand. WDM allows light at multiple different wavelengths to be combined (multiplexed) and later separated (de-multiplexed), effectively transmitting multiple communication streams via a single light pulse.
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Key words from Source 1
Communication signals, light, small lasers, strands of glass, core, travel, cladding, reflects light inward, bends
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In your own words summarise relevant information from website, book or magazine
An optic fibre is a thin fibre of glass that can carry light from one end to the other. Fibre optic cables carry communication signals, the main use of optical fibre is in long distance communication, like telephones. The core of the cable provides the pathway for light to travel. The cladding surrounds the core and reflects light inwards to avoid loss of signal.
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Report Sheet 3 How internal reflection is used in everyday life?
Source 1) Write URL, book or magazine:
|
Information from Source 1) (copy and paste from website, book or magazine)
Diamonds achieve their brilliance partially from total internal reflection. Because diamonds have a high index of refraction (about 2.3), the critical angle for the total internal reflection is only about 25 degrees. Incident light therefore strikes many of the internal surfaces before it strikes one less than 25 degrees and emerges. After many such reflections, the colors in the light are separated, and seen individually.
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Key words from Source 1
total internal reflection, high index of refraction, critical angle, incident light, strikes, internal surfaces, reflections, separated
|
In your own words summarise relevant information from website, book or magazine
The light that is seen upon a diamond (the shininess), is due to total internal reflection. Diamonds have a high index of refraction, so the critical angle for the total internal reflection is only roughly 25 degrees. So incident light strikes many of the internal surfaces, after all the reflections, the colours in the light are separated, and seen individually.
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Summary of information
:
What is internal reflection and how do we use it?
Using the information you have gathered write a summary paragraph explaining what internal reflection is and how it can be used in everyday life.
When the angle of incidence is greater than the critical angle all the waves reflect back into the medium and total internal reflection occurs. Internal reflection can be seen in everyday life quite a bit. Internal reflection can be seen in optic fibres. Optic fibres are thin fibres of glass that can carry light from one end to the other. The core of the fibre provides a pathway for the light to travel. The cladding surrounds the core and reflects light inwards to avoid loss of signal. Optic fibres are mostly used for long distance communication, like telephones and the internet. Another daily phenomenon that consists of internal reflection, is the beautiful shine belonging to diamonds. The light that is seen upon a diamond (the shininess), is due to total internal reflection. Diamonds have a high index of refraction, so the critical angle for the total internal reflection is only roughly 25 degrees. So incident light strikes many of the internal surfaces, after all the reflections the colours in the light are separated, and seen individually.
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Task C:
Written Report
FUTURE (I wrote this with like 15 minutes left of class pls don't judge me)
The future of electricity includes something called fibre optics. Fibre optics are the use of thin flexible fibres of glass or other transparent solids to transmit light signals, chiefly for telecommunications or for internal inspection of the body (courtesy of google for the definition). At the moment (present time) copper wires are being used for power and such, those long wires you see connected to power poles. These copper wires are a real nuisance in my opinion. You wouldn't want to have your home under one of these suckers, because guess what, they radiate electromagnetic radiation, bummer right. You wouldn't have this problem with fibre optic cables, as they're stored under the ground, that's right all those people you've been seeing down your street digging up your neighborhood, they've been bringing you the future. In comparison to copper, a fibre optic cable has nearly 4.5 times as much capacity as the wire cable has and a cross sectional area that is 30 times less, jeepers. Fibre optics are also a bargain, yup they're cheap cheap cheap. The raw materials for glass are plentiful, unlike copper. This means glass can be made more cheaply than copper. So the future looks brights doesn't it, and you can give your mate a call using your fibre optics and tell them all about it, and don't worry you can't be tapped.
When the angle of incidence is greater than the critical angle all the waves reflect back into the medium and total internal reflection occurs. For internal reflection to occur light must travel from a dense medium to a less dense medium. If the light rays are travelling from a less dense material to a dense medium they are refracted towards the normal and if they are travelling from a dense to less dense medium they are refracted away from the normal. Internal reflection can be seen in everyday life quite a bit. Internal reflection can be seen in optic fibres. Optic fibres are thin fibres of glass that can carry light from one end to the other. The core of the fibre provides a pathway for the light to travel. The cladding surrounds the core and reflects light inwards to avoid loss of signal. Optic fibres are mostly used for long distance communication, like telephones and the internet. An advantage for optic fibres is the fact that light can not leak out of the fibre as it travels, this allows the light to go a long distance before the signal gets too week. A disadvantage of optic fibres is that they require more protection than around the cable compared to copper. Another daily phenomenon that consists of internal reflection, is the beautiful shine belonging to diamonds. The light that is seen upon a diamond (the shininess), is due to total internal reflection. Diamonds have a high index of refraction, so the critical angle for the total internal reflection is only roughly 25 degrees. So incident light strikes many of the internal surfaces, after all the reflections the colours in the light are separated, and seen individually. An advantage for diamonds is if they are cut perfectly their shine will be extravagant, a disadvantage would be if they're cut poorly, as the effect would not be as good. Different mediums have different refractive indexes, air has a low refractive index, whereas diamonds and fibre optic cables have a high refractive index, because they have a lot more matter than air does. Diamonds and Fibre optic cables are much more dense than air, which is why they have higher refractive indexes. The speed of a light wave is dependent upon the density of the medium. The more dense the medium is, the slower the light wave will move through the medium, or vice versa. I've learnt form my experiments in task A and previous similar experiments that light behaves differently when striking the boundary of different medias. In task A I used a transparent glass prism and shined a light at it. If I shined the light at an angle less than the critical angle (roughly 42 degrees), it would travel through the prism and refract out the other side, if the angle of light were greater than the critical angle it would reflect, and internal reflection would occur. At the critical angle there is both reflection and refraction. If I shined at light at a mirror it would only reflect, unlike the glass prism being able to do both reflection and refraction.
FUTURE (I wrote this with like 15 minutes left of class pls don't judge me)
The future of electricity includes something called fibre optics. Fibre optics are the use of thin flexible fibres of glass or other transparent solids to transmit light signals, chiefly for telecommunications or for internal inspection of the body (courtesy of google for the definition). At the moment (present time) copper wires are being used for power and such, those long wires you see connected to power poles. These copper wires are a real nuisance in my opinion. You wouldn't want to have your home under one of these suckers, because guess what, they radiate electromagnetic radiation, bummer right. You wouldn't have this problem with fibre optic cables, as they're stored under the ground, that's right all those people you've been seeing down your street digging up your neighborhood, they've been bringing you the future. In comparison to copper, a fibre optic cable has nearly 4.5 times as much capacity as the wire cable has and a cross sectional area that is 30 times less, jeepers. Fibre optics are also a bargain, yup they're cheap cheap cheap. The raw materials for glass are plentiful, unlike copper. This means glass can be made more cheaply than copper. So the future looks brights doesn't it, and you can give your mate a call using your fibre optics and tell them all about it, and don't worry you can't be tapped.
This is a very good report. It is a Low Excellence. For a higher grade, i would have liked to have seen more depth in your explanations of the everyday uses.
ReplyDeleteWhen I see formatting change during a paragraph, it makes me suspicious!
Hi Amber,
ReplyDeleteThis is a very thorough report for Bacteria and Disinfectants so far - well done! The Excellence part will come from your discussion so make sure you research Savlon and it's active ingredient. You will also need to reflect on your method - is there anything you would do differently next time to improve?
Miss Huddleston