Science 2017

SCIENCE 2017

Speed Distance Time Experiment

Aim:

I want to investigate the relationship between speed, distance and time.

Equipment:

• Pole with a 3.18 m string attached to it. 
• A person to run around the circle. 
• Stop watch 
• Paper & Pen to write results. 

Method:

1. Put the pole into the ground. 
2. Pull the string out to it's full length. 
3. Walk around in a circle holding the string as your guide, making the circle as you go.
4. Use the stop watch to time the person walking around the first lap.
5. Record the results. 
6. Without the person stopping, time them jogging around the second lap.
7. Record the results. 
8. For the third lap without the person stopping, time them running around the circle. 
9. Record the results.
10. Once they have finished running the third lap, the runner stops but you continue to leave the timer on for 5 more seconds. 

Results:

Distance (m)	Time (s)
20	14
40	21
60	28
60	33

Lap Number	Distance (m)	Time (s)	Lap Time	Speed (m/s)
Start	0	0	0	0
Lap 1	20	14	14	1.42
Lap 2	40	24	10	1.66
Lap 3	60	27	3	2.22
Finish	60	32	5	0

Investigating the Effect of Temperature on Reaction Rate  

Aim: I want to investigate the effect of temperature on the rate of reaction between sodium thiosulfate and hydrochloric acid. 

Equipment:  

• Beaker 
• Conical flask 
• Stopwatch 
• Measuring cylinder
• Thermometer 
• Water bath 
• Black cross on paper 
• 0.1 mol L -1 sodium thiosulfate 
• 1.0 mol L -1 hydrochloric acid 

Method:

1. Put the 'X' paper on the bench mat, and put the conical flask on top off the paper.

2. Measure 50mL of sodium thiosuflate solution and put it into the beaker.

3. Record the temperature of the sodium thiosulfate. 

4. Measure 5mL of HCL and pour this into the conical flask.

5. 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 (look look down through the mouth of the conical flask.

6. Wash out the flask thoroughly. 

7. Repeat the experiment, using a water bath to heat the sodium thiosulfate to 30℃, then 40℃ and finally 50℃. Keep the volume of acid the same each time.





Results:

17°C  took 25 seconds for the X to disappear.
30°C  took 12 seconds for the X to disappear.
40°C  took 10 seconds for the X to disappear.
( Not enough time to do 50°C )

Conclusion: 

For the chemical reaction to occur two or more particles must collide, and will need to have sufficient energy and the correct orientation. Increasing the temperature increases the kinetic energy of the particles. Increasing the likelihood of collisions occurring increases the rate of reaction.  

Investigating the Effect of Concentration on Reaction Rate

Aim: I want to investigate the effect of concentration on the rate of reaction between sodium thiosulfate and hydrochloric acid.  

Equipment:

• Conical flask 
• Measuring cylinder 
• Stopwatch 
• Black cross paper 
• 0.2 mol L -1 of sodium thiosulfate 
• 1.0 mol L -1 of hydrochloric acid

Method:  

1. Put the 'X' paper on the bench mat, and put the conical flask on top off the paper.

2. Measure 10mL of sodium thiosuflate solution and put it into the conical flask.

3. Measure 40mL of water and put it into the conical flask. Swirl the flask to mix the contents.

4. Measure 5 mL of acid. Por the acid into the conical flask, start the stopwatch, and swirl the flask. Time how long it takes for the cross to disappear.

5. Wash out the flask thoroughly. 

6. Repeat the experiment using the other volumes of sodium thiosulfate and water in the table in your sci-pads. Keep the volume of the acid the same each time. 

Results:  

10mL of Thiosulfate/40mL of Water took 540 seconds for the X to disappear.
20mL of Thiosulfate/30mL of Water took 90 seconds for the X to disappear.
30mL of Thiosulfate/20mL of Water took 60 seconds for the X to disappear.
40mL of Thiosulfate/10mL of Water took 42 seconds for the X to disappear.
50mL of Thiosulfate/0mL of Water took 35 seconds for the X to disappear.

Conclusion: 

For the chemical reaction to occur two or more particles must collide, and will need to have sufficient energy and the correct orientation. Increasing the concentration of Sodium Thiosulfate, means that more of the reactant particles were able to react. Increasing the likelihood of collisions occurring increases the rate of reaction.

Observing the Effects of Surface Area on Reaction Rate

Aim: To make simple observations during a reaction between calcium carbonate (CaCo3) chips and powder, with hydrochloric acid (HCl)

Equipment: 

• Boiling tube
• Spatula 
• Measuring cylinder 
• Hydrochloric acid 
• Calcium carbonate chips and Powder 

Method: 

1. Measure 2ml of hydrochloric acid and pour this into your boiling tube.

2. 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: The reaction of the Calcium Carbonate powder and Hydorchloric acid was vigorous and the Calcium Carbonate dissolved rapidly as bubbles are being produced.


3. Repeat the experiment, but this time use a chip of calcium carbonate that is roughly the same size as the spatula of the powder you used previously. Record your observations below:

Observations of CaCo3 chip: The Calcium Carbonate chip and Hydrochloric acid had a slower reaction, so it took a lot longer to dissolve than the Calcium Carbonate powder. Bubbles were still being produced but because the reaction was slow, so was the production of bubbles.


Conclusion: 

For the chemical reaction to occur two or more particles must collide, and will need to have sufficient energy and the correct orientation. Using Calcium Carbonate powder will increase the surface area of the reactants. This means that more particles are able to collide, resulting in more collisions occurring and an increase of the rate of reaction.  Using a Calcium Carbonate chip will decrease the surface area . This means that less particles are able to collide resulting in less collisions occurring and a decrease in the rate of reaction. 

Observing the Effect of a Catalyst on a Chemical Reaction 

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 
• Granulated zinc
• Copper turnings
• Dilute sulfuric acid  

Method: 

1. Add roughly the same mass of zinc to test tubes 1 and 3.  

2. Add roughly the same mass of copper to test tubes 2 and 3. 

3. Add 5 mL of dilute sulfuric acid to test tubes 1, 2 and 3 and note the rate of production of gas bubbles. 

                                              

Observations: 

Test Tube 1: This Test Tube contained Zinc and Acid and it was slow reacting. Bubbles were still being produced but because it was slow reacting the production of bubbles was slow too. 

Test Tube 2: This Test Tube contained Copper and Acid and it didn't react at all. The Copper and Sulfuric Acid particles were unable to collide.  

Test Tube 3: This Test Tube contained Zinc, Copper & Sulfuric Acid and was the one that reacted the most out of all 3 of them, continuously reacting and producing bubbles rapidly.  

Define the term 'Catalyst': 

A substance that changes the rate of the reaction, but is not used up in the reaction. 

Outline the purpose of Test Tube 2: 

The purpose of Test Tube 2 is to show that there is no reaction between the Copper and Acid. 

Suggest a method to show copper was not used up in the reaction in Test Tube 3:

A Catalyst is not used up in a reaction, the mass should be the same during the reaction. Therefore you could measure the mass of copper at the start of the reaction and compare it to the mass at the end of the reaction.

How to Make a Salt using Metals, Insoluble Bases or Insoluble Carbonates 

Aim: To produce copper sulfate salts by reacting copper oxide with an acid.

Equipment: 

• Copper oxide powder 
• Bunsen burner 
• Evaporating basin 
• Tripod 
• Gauze mat
• Funnel 
• Filter paper
• Thermometer 
• Spatula 
• Stirring rod 
• Dilute (1 mol L-1 sulfuric acid 
• 50 mL measuring cylinder 
• Two 100 mL beakers 
• 
  

Method:

1. Add 20 mL of sulfuric acid to a 100 mL beaker. Heat the acid until it reaches 70℃. Turn off your Bunsen burner. Do not boil the acid. 

2. Once heated, use a spatula to add pea-sized portions of copper oxide to the beaker. Stir the mixture for 30 seconds.

3. Repeat step 2 until no more will dissolve. Allow the beaker to cool.

4. Fold the filter paper and place it in the funnel. Place the filter funnel into a second beaker. 

5. Make sure the beaker is cool enough to hold at the top. the contents should still be hot. You may need your teacher to complete this step. 

6. Gently swirl the contents of the beaker to mix, and then pour into the filter paper in the funnel. Allow to filter through.

7. Rinse the beaker you used to heat the mixture previously, and place it back on top of your tripod filled
with 50-60 mL of water. 

8. Place the evaporating basin on top of this beaker and carefully our some of the solution from the other beaker into the evaporating basin.

9. Gently eat the beaker until the solution in the evaporating basin has reduced by half

10. Leave the evaporating basin to cool. Once cool, move the evaporating basin to a warm place where it will not be disturbed (e.g. a window-sill) and observe over the next few days 

Observations: 

While the copper oxide powder and hydrochloric acid were reacting it started off like a mucky black colour then turned into a beautiful blue after being filtered. The water evaporated and reduced it.

Bacteria and Disinfectants 

Research:

Purpose of investigation: How concentration can affect the performance rate of disinfectant in killing micro-organisms.

What is bacteria? 
Bacteria are tiny, single cell micro-organisms. Bacteria is known to be one of the first life forms on earth and inhabit soil, water, acidic hot springs, radioactive waste ect;

What is the life process of bacteria? 
MRS GREN - Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion and Nutrition.

How does a disinfectant work?  
Disinfectants inhibit bacteria rapidly when they come into contact. Disinfectant can kill bacteria on non living objects as well as living objects.

What is Savlon?
Savlon is an antiseptic that is used to prevent infections and to clean minor injuries, wounds, cuts, grazes, bites, stings, and minor burns.

What is the active ingredient in Savlon and how does it work? 
The active ingredient in Savlon is Cetrimide. Cetrimide is an antiseptic that is a mixture of different quaternary ammonium salts. When Cetrimide and bacteria come into contact it has been found that it will inhibit the bacteria within 15 seconds, which works by disruption of the cell wall and stopping the function of enzymes in the nucleoid.

URLS: https://en.m.wikipedia.org/wiki/Chloroxylenol
https://en.wikipedia.org/wiki/Bacteria

Trial Experiment:

Aim: I want to investigate how the concentration of dettol can affect the growth and reproduction of bacteria.

Hypothesis: I predict that a higher concentration of Dettol, will create a larger clear zone surrounding the bacteria.

Independent Variable: Concentration of Dettol ( Eg. 100%, 10%, 1%)
Dependent Variable: Inside of the clear zone (measured in mm)
Other Variables: Temperature to make sure that all three agar plates at the same temperature, eg. put them into an incubator, The sterility of conditions to make sure nothing is contaminated and the size of the fliter paper disk containing the dettol to make the test fair.

Equipment:

• 3 Agar Plates
• Dettol
• Yogurt
• Filter Paper 
• Hole Punch
• Water
• Permanent marker
• Ruler
• Ethanol
• Dropper
• Paper towel 
• Spotting Tiles
• Cotton buds 
• Tweezers
• Cello-tape

Method: 

1. Get your equipment.

2. Start by using a permanent marker (on the jelly side) to divide the agar plate into 4 sections. In each section label them with the different concentrations of dettol. (eg. 100%, 10%, 1% and water)

3. Use a cotton bud to smear the yogurt over the jelly side of the agar plate.

4. Using a dropper, put a few drops of dettol into a spotting tile. This is the concentration of 100%, and again using the dropper put 1 drop of the dettol into a separate tile. Then this time add 9 drops of water to equal a concentration of 10%. Repeat this step again by taking a drop of the 10% concentration, to then create a concentration of 1%. (Make sure the dropper is always clean so there is no contamination)

5. Then punch 4 full circles into the filter paper using a hole punch. (If the circles aren't the same the test won't be fair)

6. Dip your tweezers in ethanol and put it through the flame to sterilize it.

7. Use the tweezers to dip the filter paper into the different concentrations. Blot the filter paper onto a paper towel to get rid of any excess. Then put them onto the agar plate. 

8. Once you've done that use the cello-tape to tape around the edges
and wait for the bacteria to grow.

9. Measure the diameter of the clear zone.

*Unfortunately, I was unable to record the results as I was away the day of the experiment*

Experiment 

Aim: I want to investigate how the different concentrations of Savlon can affect the growth and reproduction of bacteria.

Hypothesis: I predict that a higher concentration of Savlon will create a larger clear zone surrounding the bacteria because the purpose of Savlon is to inhibit the growth and reprodution of micro-organisms.

Independent Variable: Concentration of Savlon ( Eg. 100%, 10%, 1% and the control which is water)
Dependent Variable: Inside of the clear zone (measured in mm)
Other Variables: Temperature to make sure that all three agar plates at the same temperature, eg. put them into an incubator, The sterility of conditions to make sure nothing is contaminated and the size of the fliter paper disk containing the dettol to make the test fair.

How will you make sure the data is accurate? To ensure that the results we collect are reliable we will carry out a fair test and repeat the same experiment, on 3 different agar plates to see if there is a consistency with the results.

Equipment:

• 3 Agar Plates,
• Savlon
• Yogurt
• Conical Flask 
• Water
• Filter Paper 
• Hole Punch
• Permanent marker
• Ruler
• Ethanol
• Dropper
• Paper towel 
• Spotting Tiles
• Tweezers
• Cello-tape

Method: 

1. Get your equipment.


2. Start by using a permanent marker (on the jelly side) to divide the agar plate into 4 sections. In each section label them with the different concentrations of savlon. (eg. 100%, 10%, 1% and water)

3. Get a conical flask and add the yogurt. Then put some water to dilute it, which will make the yogurt more of a runnier texture. This will make it easier for you to just pour it onto the agar plate and move it around so the whole surface is covered, and you can get a clear look at the bacteria.


4. Using a dropper, put a few drops of savlon into a spotting tile. This is the concentration of 100%, and again using the dropper put 1 drop of the savlon into a separate tile. Then this time add 9 drops of water to equal a concentration of 10%. Repeat this step again by taking a drop of the 10% concentration, to then create a concentration of 1%. (Make sure the dropper is always clean so there is no contamination)

5. Then punch 4 full circles into the filter paper using a hole punch. (If the circles aren't the same the test won't be fair)

6. Dip your tweezers in ethanol and put it through the flame to sterilize it.

7. Use the tweezers to dip the filter paper into the different concentrations. Blot the filter paper onto a paper towel to get rid of any excess. Then put them onto the agar plate. 

8. Once you've done that use the cello-tape to tape around the edges and wait for the bacteria to grow.

9. Measure the diameter of the clear zone.

10. Repeat this exact same experiment 2 more times so you've carried out a fair test.

* The changes I made to my method were: How I applied the yogurt onto the agar plate. My first method was to smear it on with the cotton bud but that left smeared marks over the agar plate. So I changed it to adding yogurt and water into a conical flask to dilute it, to be able to easily pour it onto the agar plate. We also changed the type of disinfectant we were using. For the trial experiment we used dettol, but found that Savlon would work better so for the actual experiment we used Savlon*

*Some difficulties I faced were: Not draining enough of the excess yogurt from the agar plate, which I believe could've made the data less accurate because there wasn't the same amount of yogurt on each agar plate so there wouldn't be a consistency in the results.*

Results and Analysis: 

Concentration	Clear Zone of Agar Plate 1 (mm)	Clear Zone of Agar Plate 2 (mm)	Clear Zone of Agar Plate 3 (mm)	Average
0%	0	0	0	0
1%	2	1	3	2
10%	6	8	8	7.3
100%	15	14	12	13.

Conclusion:

The aim of this experiment was to investigate how different concentrations of Savlon can affect the growth and reproduction of bacteria. I predicted that that a higher concentration of Savlon would create a larger clear zone surrounding the bacteria, because the purpose of Savlon is to inhibit the growth and reproduction of micro-organisms. After analysing my data/graph I noticed an increasing trend had formed. I conclude that as you increase the concentration of the Savlon, the size of the clear zone surrounding the bacteria will also increase.

Explanation:

Bacteria are tiny, single cell micro-organisms. Bacteria is known to be one of the first life forms on earth and inhabit soil, water, acidic hot springs, radioactive waste ect; Bacteria uses the cycle of MRS GREN (Movement, Reproduction, Sensitivity, Growth, Respiration, Excretion and Nutrition.) For this experiment we only focused on Growth, Reproduction and Nutrition. Bacteria is gel like and is composed of mainly water, enzymes, nutrients, wastes, and gases. Inside the 'soup' of the cell is called the Cytoplasm that contains the nucleoid (holds DNA for essential life), Rimbosomes (where proteins are made in the cell), Plasmids (extra bits of DNA) but mostly water as I've already mentioned. The outer structure of the bacteria has 3 layers. The inside layer is called the Cell Membrane which is used for nutrition and excretion. The middle layer is called the Cell Wall which is a structure to give the bacteria shape, and to protect it as well. The outer layer is called the Capslue and is the protective outer layer of the cell. On the outside of the Capsule are Pili's that are used to build bridges to other bacteria. Then at an bottom of the bacteria is the Flagellum, which is basically the tail and is used for movement. Bacteria reproduces asexually, meaning it only needs a single cell to reproduce. Being asexual means that all offspring are clones of the parent and have the same number of chromosomes. Bacteria are fast at reproducing and can reproduce every 20 minutes. The process of a bacteria's reproduction is called Binary Fission. During Binary Fission, for bacteria to reproduce it will replicate it's DNA. Then as the DNA is pulled to separate sides of the bacteria the cell wall will start to grow. The cell wall of the bacteria will then begin to slowly split because of the rapid growth of the cell wall. The new cell wall of the bacteria becomes fully developed, making a complete split of the bacteria to form two daughter cells. Most bacteria are autotrophs meaning they are organisms that produce complex organic compounds like carbohydrates, fats, and proteins from simple substances present in its surrounding. They are generally using energy from photosynthesis or chemical reactions. Nutrition can be transported to bacteria in 2 different ways - Diffusion and Active Transport. Diffusion Transport is when there is a high concentration outside of the cell and it will have a low concentration on the inside. Active Transport is when there is a low concentration outside the cell and a high concentration inside of the cell and it will require energy to be transported.


Savlon is an antiseptic that is used to prevent infections and to clean minor injuries, wounds, cuts, grazes, bites, stings, and minor burns. The active ingredients in Savlon are - Chlorhexadine  C₂₂H₃₀Cl₂N₁₀ and Certrimde (C16H33)N(CH3)3. Cetrimide is an antiseptic that is a mixture of different ammonium salts. Chlorhexidine is a disinfectant as well as an antiseptic that is used for skin disinfection and sterilisation. In the Savlon we used for the experiment there was 0.3% of Chlorhexadine and 3.0% of Cetrimide. When Cetrimide and Chlorhexidine come into contact with bacteria it has been found that it will inhibit the bacteria within 15 seconds. This works by oxidising the molecules present on the bacteria's surface, which will then disrupt the cell wall and the proteins on the surface to damage them, that will then stop the function of enzymes in the nucleoid. This is called cell lysis which breaks apart the Cell Membrane. The function of the Cell Membrane is to let food in and waste out, so by disrupting this part of the bacteria it won't be able to survive. Savlon enters the bacteria by diffusion transport when there is a high concentration outside of the cell and a low concentration on the inside of the cell and it attacks the Cell Membrane. Therefore, the Cell Membrane is no longer able to function correctly and transport the essential nutrients for the bacteria to survive. The Cell Membrane also consists of Hydrophile molecules that are attracted to water and Lipophilicity molecules that are attracted to fats and oils, and because most bacteria are autotrophs they produce carbohydrates, fats, and proteins from simple substances surrounding it. Therefore disinfectants dissolve the Cell Membrane because they interact with both Hydophile and Lipophilicity molecules. After analysing my data/graph I noticed a trend when I increased the concentration of Savlon, the size of the clear zone surrounding the bacteria would also increase. 

Evaluation: 

I think the experiment and it's data was reasonably reliable, and the results weren't too far off one another being in a 1-3mm of the clear zone range from each other. So the experiment was pretty accurate. This data shows us that by increasing the concentration of Savlon, it will also increase the size of the clear zone around the disk. I have proven my hypothesis that a higher concentration of Savlon will create a larger clear zone surrounding the bacteria because the purpose of Savlon is to inhibit the growth and reprodution of micro-organisms. Some difficulties I faced throughout the experiment was not draining enough of the excess yogurt from the agar plate, which though could've made the data less accurate because there wasn't the same amount of yogurt on each agar plate so there could be an inconsistency in the results, but after analysing the data I don't think it affected it too much. I also altered two things in my method after the trial investigation. They were 1. How I applied the yogurt onto the agar plate. In my first method I smeared the yogurt on with a cotton bud, but that left marks over the agar plate. So I changed the method to adding yogurt and water into a conical flask to dilute it, so it would be easily pour it onto the agar plate. 2. We changed the type of disinfectant we were using. For the trial experiment we used dettol, but found that Savlon would work better for what we were investigating so for the experiment we used Savlon. After doing this investigation I have no further questions, but I believe I have a better knowledge on bacteria and disinfectants than what I did before starting the investigation.