Science
Science this quarter, we learned about Chemistry. In chemistry we learned about chemical reactions, balancing equation and stoichiometry. Below is my lab report on the experiment we did in Chemistry
Lab Report
Introduction
What is vinegar and what does it contain?
Vinegar is made from the fermentation of Ethanol, where bacteria is used to break down the ethanol and aethic acid into by products
Methods that can be used to analyze the content of vinegar.
Procedure:
Be sure to record all data in the table on your results sheet.
1. Clean your buret, rinse it with distiled water and then rinse the buret with 3 x 5 mL sample of titrant (NaOH). Allow this solution to drain from the bottom by opening the stopcock.
2. Make sure the whole interior of the buret has been sufficiently rinsed with distilled water and the titrant solution. Discard the titrant used to rinse the buret and close the stopcock.
3. Fill the buret with titrant as close as you can to the top of the buret. Now open the stopcock and allow some of the titrant to be released. (This eliminates any bubbles at the tip which can cause error in your data.) Try to start your titration with the titrant level near the 0.00 mL mark. However, it does not have to be exactly 0.00 mL, so please do not waste time. Always record this initial volume. The technique for reading the values from a buret are the same as those for the graduated cylinder, read the bottom of the meniscus.
Using the buret provided for you, carefully measure and pour 25.00 mL of vinegar into a 250.0 mL Erlenmeyer flask. Calculate the mass assuming the density is 1 g/mL.
Add 3-5 drops of phenolphthalein indicator to the flask.
After properly cleaning your buret, fill the buret with sodium hydroxide solution and record the initial volume.
Titrate your vinegar sample with the sodium hydroxide solution, making sure to gently swirl your flask as you are adding the sodium hydroxide. Add the sodium hydroxide until you have a very slight pink color that remains for more than thirty seconds. You will see a pink color as you add the sodium hydroxide to the flask but will notice when you swirl the flask it disappears. This means that you have not reached the equivalence point yet and need to add more base. Once the color remains for more than thirty seconds, you can be confident that you have reached the equivalence point for your titration.
On your first attempt at performing the titration, you may find you have passed the equivalence point and now have a deep pink color instead of slightly pink. This is okay since you will not count this trial run when you work on calculations with your data. This trial run is to give you a good idea as to the number of milliliters of base that need to be added to reach the equivalence point. Since you are measuring the same amount of vinegar each time, you now will know when you are getting relatively close to the equivalence point and then you can add more carefully as you get closer to the volume of base that you need.
Repeat steps 1-5 three more times.
Using the data from step 5, calculate the average percentage of acetic acid in vinegar. Provide a sample calculation for each calculation you perform in the space provided under calculations.
Titration – what is it? how does it work?
A titration is a method where a solution of a concentration is known that can be used to determine the concentration of an unknown solution
A titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution.
Indicator – what is it? how does it work?
Indicators are weak chemicals that will changes its color depending on each pH level of a solution
How it works:
Drop 3 – 4 drops each 100 ml of the chemical reactions; do not drop to much because indicators are weak. See the indicator it will slowly change its colors.
Equivalent point and end point – what are they
End point is the last point in titration, which means that the titration process has already finished.
Equivalence point is the middle point where the acid has reach the exact pH meter.
Objective
The aim of this experiment is to determine the molarity of ethanoic acid in vinegar (CH3COOH) by adding a volume of sodium hydroxide (NaOH).
Hypothesis
The molarity of Vinegar is equal to the molarity of NaOH
Variables
· Independent Variables: Volume of acid (0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL)
· Dependent Variable: the molarity of acid
· Controlled Variables: the molarity of sodium hydroxide (1M), the type of vinegar (CH3COOH), room temperature, pressure, the addition of phenolphthalein indicator (3 drops), the volume of distilled water into the acid (50 mL).
Tools and Materials
· Burette (1)
· 250 mL Erlenmeyer flask (5)
· 50 mL measuring cylinder (1)
· 10 mL measuring cylinder (1)
· 250 mL beaker (3)
· 150 mL beaker (2)
· 10 mL beaker (1)
· Retort stand and clamp (1)
· 25 mL of vinegar (CH3COOH)
· 600 mL of sodium hydroxide (NaOH)
· 20 ml of phenolphthalein indicator
· 1 L of distilled water
· Wash bottle (1)
· 5 mL Pipette (3)
· Dropper (1)
· Funnel (1)
· Goggles
· Gloves
· Lab Coat
· Sheet of white and dark paper
Method
1. Rinse the tools (burette, flasks, and beakers).
2. Make sure the burette stopcock is closed.
3. Fill the burette with 25 mL of sodium hydroxide.
4. Place a beaker under the burette.
5. Open the stopcock to allow the liquid to drain out into the beaker and then close the stopcock. Make sure that there is no air bubbles remain in the stopcock.
6. Remove the beaker.
7. Using the 5 mL pipette, pour 0.5 mL of vinegar solution into the Erlenmeyer flask.
8. Measure 50 mL of distilled water using the 50 mL measuring cylinder and add it to the vinegar solution.
9. Add 3 drops of phenolphthalein into the vinegar solution in the Erlenmeyer flask. The solution should remain colourless at this point.
10. Place the flask under the burette. Put a sheet of white paper under the flask to make the endpoint easier to see.
11. Read the volume of the sodium hydroxide in the burette. This is your initial volume. Reading is made easier by holding a piece of dark paper behind the burette.
12. Slowly open the burette stopcock and add some sodium hydroxide into the flask, while doing so, swirl the flask. Observe the colour of the solution, you may notice a temporary colour change in the solution.
13. Continue adding the sodium hydroxide. The colour change will take longer to disappear. This is a signal that the endpoint is getting closer and the sodium hydroxide should be added dropwise.
14. Stop adding the sodium hydroxide when a permanent colour change is observed (a pale pink; longer than 30 seconds). This indicates that the solution has reached its endpoint.
15. Record the volume of sodium hydroxide in the burette. This is your final volume. Subtract the initial volume from the final volume to determine the volume of sodium hydroxide added.
16. Repeat step 1 to 15 using different volume of vinegar: 1mL, 1.5mL, 2mL and 2.5mL.
17. Refill the burette with sodium hydroxide solution if it was not enough but remember to record the volume of sodium hydroxide used.
18. Repeat step 1 to 17 three times to obtain accurate results.
Volume of Vinegar (mL)
1st Trial (mL)
Volume of NaOH
2nd Trial (mL)
Volume of NaOH
3rd Trial (mL)
Volume of NaOH
0.5 ml
2.6
2.4
2.4
1 ml
4.7
4.8
4.9
1.5 ml
6.5
6.6
6.8
2 ml
10.6
9
11
2.5 ml
11.3
11
11.3
Data Collection
Data Processing
Molarity = Moles / Volume (1000 cm3)
Molarity of NaOH = Moles/ Volume
Molarity of NaOH
Volume of NaOH
Moles of NaOH
Moles of Vinegar
Volume of Vinegar
Molarity of Vinegar
1M
2.467cm3
0.002467 mole
0.002467mole
50.5cm3
0.04885M
1M
4.8 cm3
0.0048mole
0.0048mole
51cm3
0.09411M
1M
6.634cm3
0.006634mole
0.006634mole
56.5cm3
0.11741M
1M
10.2cm3
0.00102mole
0.00102mole
52cm3
0.02154M
1M
11.2cm3
0.00112mole
0.00112mole
52.5cm3
0.02133M
Data Presentation
Data Presentation
Discussion
On this data presentation, it clearly shows that the numbers on the left are the volume of the NaOH. The numbers below are the volume of Vinegar. The color yellow is shown as the first trial, while the color pink is the second trial and last but not least the color blue is third trial. This is a graph which shows the data received based on the experiment. On the first volume it shows that the first trial is around 2.6 mL of NaOH. Then the second and the third trial had the same result, which were 2.4 mL. Then on the second volume, the first trial resulted 4.7 mL. On the second trial the result was 4.8 mL. Last but not least the third trial was 4.9 mL. On the third volume, the first trial resulted 6.5 mL. Then on the second trial the result was 6.6 mL. Last but not least the last trial was 6.8 mL. On the fourth volume of vinegar we used 2mL of Volume of Vinegar whereas the first trial resulted 10.6 mL. Then for the second trial, the result was 9mL and last but not least the third trial was 11 mL. The first trial was 11.3 mL. Then on the second one was 11mL and last the third trial it was 11.3mL. From this data it is defined that the data was consistent as the numbers collected was near to each other, it is quite consistent which is a good thing.
The pattern shown on this graph is that each time the volume of vinegar is higher; the NaOH gets higher as well. But then on the trials, they are near with each other. It is clearly shown on the table of data processing that my hypothesis was correct, as the molarity of vinegar is equal to the molarity of NaOH which means that this experiment was a success and have reached our goal.
Evaluation
The method used for this experiment was rather a success, it seemed that there is no much weakness. The weakness of this method is based on the person who uses the method. In order to not show any weaknesses towards this method, we should be careful, be precised and don’t rush. First to be careful, what I mean by this is that when filling the tube with NaOH, make sure nothing was spilled, clean the tubes and beakers properly. Then precised, what I mean by is to take notes clearly, calculate and check the points and when filling it with chemical make sure it is the right measurement. Last but not least, we must be patient and don’t rush. If we are patient, we could get successful result. In order to create this method without weaknesses is by improving ourselves to do the things that are written above and everything is going to go well.
Conclusion
From this experiment I learned how to find the exact measurement of Chemical that was used. I learned more on how to be patient and to be precised whcn experimenting, which we should drop little by little of NaOH to the mixed chemical. I think that the studies was a good addition for me, which I can calculate the molarity easily and it seemed that the result was the same as my hypothesis. Based on the data, we did 3 trials for each volume of vinegar and that the results were quiet near to each other. Afterwards after processing the data, it shows the hypothesis was correct and that my experiment was a huge success.The problems I occurred during this experiment, was most probably impatient and I was not careful, as I spilled NaOH and it affected the experiment as the liquid tremendously drops all the time. I was impatient cause on my mind, I was set to do things in a hurry cause I wanted to get things over with. But that was wrong, and I should do the opposite to create the success. The method was reliable because with it, I was able to get a result that was the same as my hypothesis and I think that is valid as we did the procedure and we received the result we wanted. There is no improvements for the method, but improvement for ourselves as we need to be extra careful, extra precised and extra patient. With three of those things, I’m sure you’ll have a huge success on this experiment.
Reference
"What Is Vinegar?" About.com Food Reference. N.p., n.d. Web. 16 Sept. 2013.
Becker, Scott. "How Does an Acid Base Indicator Work? | EHow." EHow. Demand Media, 25 July 2009. Web. 16 Sept. 2013.
"The Analysis of Vinegar." The Analysis of Vinegar. N.p., n.d. Web. 16 Sept. 2013.
"What Is an Indicator?" What Is an Indicator? N.p., n.d. Web. 17 Sept. 2013.
"How Does the Equivalence Point of a Titration Differ from Its End Point?" WikiAnswers. Answers, n.d. Web. 17 Sept. 2013.
REFLECTION
This is my best sample, because I think that I have done well on it and I received 4/6 and 3/6 and 5/6 for my grades. The experiment was to find the right amount of solution that would change a certain solution into the right bright purple. It took us a lot of experiments but in end, we made it and I got a quite satisfying result. I think my attitude during the experiment was well that was why I received a 5 out of 6 in the criteria and the others was just a passing grade. In the near future I would improve by showing more effort in my work so that I could get a better grade in the future.
This quarter, it could be related to the concept intercultural awareness by is that we had nothing to do with intercultural awareness. Tho, we showed respect to the teacher, submitting on time. We treated the equipments properly and neatly this quarter and that we had a great time.
Lab Report
Introduction
What is vinegar and what does it contain?
Vinegar is made from the fermentation of Ethanol, where bacteria is used to break down the ethanol and aethic acid into by products
Methods that can be used to analyze the content of vinegar.
Procedure:
Be sure to record all data in the table on your results sheet.
1. Clean your buret, rinse it with distiled water and then rinse the buret with 3 x 5 mL sample of titrant (NaOH). Allow this solution to drain from the bottom by opening the stopcock.
2. Make sure the whole interior of the buret has been sufficiently rinsed with distilled water and the titrant solution. Discard the titrant used to rinse the buret and close the stopcock.
3. Fill the buret with titrant as close as you can to the top of the buret. Now open the stopcock and allow some of the titrant to be released. (This eliminates any bubbles at the tip which can cause error in your data.) Try to start your titration with the titrant level near the 0.00 mL mark. However, it does not have to be exactly 0.00 mL, so please do not waste time. Always record this initial volume. The technique for reading the values from a buret are the same as those for the graduated cylinder, read the bottom of the meniscus.
Using the buret provided for you, carefully measure and pour 25.00 mL of vinegar into a 250.0 mL Erlenmeyer flask. Calculate the mass assuming the density is 1 g/mL.
Add 3-5 drops of phenolphthalein indicator to the flask.
After properly cleaning your buret, fill the buret with sodium hydroxide solution and record the initial volume.
Titrate your vinegar sample with the sodium hydroxide solution, making sure to gently swirl your flask as you are adding the sodium hydroxide. Add the sodium hydroxide until you have a very slight pink color that remains for more than thirty seconds. You will see a pink color as you add the sodium hydroxide to the flask but will notice when you swirl the flask it disappears. This means that you have not reached the equivalence point yet and need to add more base. Once the color remains for more than thirty seconds, you can be confident that you have reached the equivalence point for your titration.
On your first attempt at performing the titration, you may find you have passed the equivalence point and now have a deep pink color instead of slightly pink. This is okay since you will not count this trial run when you work on calculations with your data. This trial run is to give you a good idea as to the number of milliliters of base that need to be added to reach the equivalence point. Since you are measuring the same amount of vinegar each time, you now will know when you are getting relatively close to the equivalence point and then you can add more carefully as you get closer to the volume of base that you need.
Repeat steps 1-5 three more times.
Using the data from step 5, calculate the average percentage of acetic acid in vinegar. Provide a sample calculation for each calculation you perform in the space provided under calculations.
Titration – what is it? how does it work?
A titration is a method where a solution of a concentration is known that can be used to determine the concentration of an unknown solution
A titration is a technique where a solution of known concentration is used to determine the concentration of an unknown solution.
Indicator – what is it? how does it work?
Indicators are weak chemicals that will changes its color depending on each pH level of a solution
How it works:
Drop 3 – 4 drops each 100 ml of the chemical reactions; do not drop to much because indicators are weak. See the indicator it will slowly change its colors.
Equivalent point and end point – what are they
End point is the last point in titration, which means that the titration process has already finished.
Equivalence point is the middle point where the acid has reach the exact pH meter.
Objective
The aim of this experiment is to determine the molarity of ethanoic acid in vinegar (CH3COOH) by adding a volume of sodium hydroxide (NaOH).
Hypothesis
The molarity of Vinegar is equal to the molarity of NaOH
Variables
· Independent Variables: Volume of acid (0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL)
· Dependent Variable: the molarity of acid
· Controlled Variables: the molarity of sodium hydroxide (1M), the type of vinegar (CH3COOH), room temperature, pressure, the addition of phenolphthalein indicator (3 drops), the volume of distilled water into the acid (50 mL).
Tools and Materials
· Burette (1)
· 250 mL Erlenmeyer flask (5)
· 50 mL measuring cylinder (1)
· 10 mL measuring cylinder (1)
· 250 mL beaker (3)
· 150 mL beaker (2)
· 10 mL beaker (1)
· Retort stand and clamp (1)
· 25 mL of vinegar (CH3COOH)
· 600 mL of sodium hydroxide (NaOH)
· 20 ml of phenolphthalein indicator
· 1 L of distilled water
· Wash bottle (1)
· 5 mL Pipette (3)
· Dropper (1)
· Funnel (1)
· Goggles
· Gloves
· Lab Coat
· Sheet of white and dark paper
Method
1. Rinse the tools (burette, flasks, and beakers).
2. Make sure the burette stopcock is closed.
3. Fill the burette with 25 mL of sodium hydroxide.
4. Place a beaker under the burette.
5. Open the stopcock to allow the liquid to drain out into the beaker and then close the stopcock. Make sure that there is no air bubbles remain in the stopcock.
6. Remove the beaker.
7. Using the 5 mL pipette, pour 0.5 mL of vinegar solution into the Erlenmeyer flask.
8. Measure 50 mL of distilled water using the 50 mL measuring cylinder and add it to the vinegar solution.
9. Add 3 drops of phenolphthalein into the vinegar solution in the Erlenmeyer flask. The solution should remain colourless at this point.
10. Place the flask under the burette. Put a sheet of white paper under the flask to make the endpoint easier to see.
11. Read the volume of the sodium hydroxide in the burette. This is your initial volume. Reading is made easier by holding a piece of dark paper behind the burette.
12. Slowly open the burette stopcock and add some sodium hydroxide into the flask, while doing so, swirl the flask. Observe the colour of the solution, you may notice a temporary colour change in the solution.
13. Continue adding the sodium hydroxide. The colour change will take longer to disappear. This is a signal that the endpoint is getting closer and the sodium hydroxide should be added dropwise.
14. Stop adding the sodium hydroxide when a permanent colour change is observed (a pale pink; longer than 30 seconds). This indicates that the solution has reached its endpoint.
15. Record the volume of sodium hydroxide in the burette. This is your final volume. Subtract the initial volume from the final volume to determine the volume of sodium hydroxide added.
16. Repeat step 1 to 15 using different volume of vinegar: 1mL, 1.5mL, 2mL and 2.5mL.
17. Refill the burette with sodium hydroxide solution if it was not enough but remember to record the volume of sodium hydroxide used.
18. Repeat step 1 to 17 three times to obtain accurate results.
Volume of Vinegar (mL)
1st Trial (mL)
Volume of NaOH
2nd Trial (mL)
Volume of NaOH
3rd Trial (mL)
Volume of NaOH
0.5 ml
2.6
2.4
2.4
1 ml
4.7
4.8
4.9
1.5 ml
6.5
6.6
6.8
2 ml
10.6
9
11
2.5 ml
11.3
11
11.3
Data Collection
Data Processing
Molarity = Moles / Volume (1000 cm3)
Molarity of NaOH = Moles/ Volume
Molarity of NaOH
Volume of NaOH
Moles of NaOH
Moles of Vinegar
Volume of Vinegar
Molarity of Vinegar
1M
2.467cm3
0.002467 mole
0.002467mole
50.5cm3
0.04885M
1M
4.8 cm3
0.0048mole
0.0048mole
51cm3
0.09411M
1M
6.634cm3
0.006634mole
0.006634mole
56.5cm3
0.11741M
1M
10.2cm3
0.00102mole
0.00102mole
52cm3
0.02154M
1M
11.2cm3
0.00112mole
0.00112mole
52.5cm3
0.02133M
Data Presentation
Data Presentation
Discussion
On this data presentation, it clearly shows that the numbers on the left are the volume of the NaOH. The numbers below are the volume of Vinegar. The color yellow is shown as the first trial, while the color pink is the second trial and last but not least the color blue is third trial. This is a graph which shows the data received based on the experiment. On the first volume it shows that the first trial is around 2.6 mL of NaOH. Then the second and the third trial had the same result, which were 2.4 mL. Then on the second volume, the first trial resulted 4.7 mL. On the second trial the result was 4.8 mL. Last but not least the third trial was 4.9 mL. On the third volume, the first trial resulted 6.5 mL. Then on the second trial the result was 6.6 mL. Last but not least the last trial was 6.8 mL. On the fourth volume of vinegar we used 2mL of Volume of Vinegar whereas the first trial resulted 10.6 mL. Then for the second trial, the result was 9mL and last but not least the third trial was 11 mL. The first trial was 11.3 mL. Then on the second one was 11mL and last the third trial it was 11.3mL. From this data it is defined that the data was consistent as the numbers collected was near to each other, it is quite consistent which is a good thing.
The pattern shown on this graph is that each time the volume of vinegar is higher; the NaOH gets higher as well. But then on the trials, they are near with each other. It is clearly shown on the table of data processing that my hypothesis was correct, as the molarity of vinegar is equal to the molarity of NaOH which means that this experiment was a success and have reached our goal.
Evaluation
The method used for this experiment was rather a success, it seemed that there is no much weakness. The weakness of this method is based on the person who uses the method. In order to not show any weaknesses towards this method, we should be careful, be precised and don’t rush. First to be careful, what I mean by this is that when filling the tube with NaOH, make sure nothing was spilled, clean the tubes and beakers properly. Then precised, what I mean by is to take notes clearly, calculate and check the points and when filling it with chemical make sure it is the right measurement. Last but not least, we must be patient and don’t rush. If we are patient, we could get successful result. In order to create this method without weaknesses is by improving ourselves to do the things that are written above and everything is going to go well.
Conclusion
From this experiment I learned how to find the exact measurement of Chemical that was used. I learned more on how to be patient and to be precised whcn experimenting, which we should drop little by little of NaOH to the mixed chemical. I think that the studies was a good addition for me, which I can calculate the molarity easily and it seemed that the result was the same as my hypothesis. Based on the data, we did 3 trials for each volume of vinegar and that the results were quiet near to each other. Afterwards after processing the data, it shows the hypothesis was correct and that my experiment was a huge success.The problems I occurred during this experiment, was most probably impatient and I was not careful, as I spilled NaOH and it affected the experiment as the liquid tremendously drops all the time. I was impatient cause on my mind, I was set to do things in a hurry cause I wanted to get things over with. But that was wrong, and I should do the opposite to create the success. The method was reliable because with it, I was able to get a result that was the same as my hypothesis and I think that is valid as we did the procedure and we received the result we wanted. There is no improvements for the method, but improvement for ourselves as we need to be extra careful, extra precised and extra patient. With three of those things, I’m sure you’ll have a huge success on this experiment.
Reference
"What Is Vinegar?" About.com Food Reference. N.p., n.d. Web. 16 Sept. 2013.
Becker, Scott. "How Does an Acid Base Indicator Work? | EHow." EHow. Demand Media, 25 July 2009. Web. 16 Sept. 2013.
"The Analysis of Vinegar." The Analysis of Vinegar. N.p., n.d. Web. 16 Sept. 2013.
"What Is an Indicator?" What Is an Indicator? N.p., n.d. Web. 17 Sept. 2013.
"How Does the Equivalence Point of a Titration Differ from Its End Point?" WikiAnswers. Answers, n.d. Web. 17 Sept. 2013.
REFLECTION
This is my best sample, because I think that I have done well on it and I received 4/6 and 3/6 and 5/6 for my grades. The experiment was to find the right amount of solution that would change a certain solution into the right bright purple. It took us a lot of experiments but in end, we made it and I got a quite satisfying result. I think my attitude during the experiment was well that was why I received a 5 out of 6 in the criteria and the others was just a passing grade. In the near future I would improve by showing more effort in my work so that I could get a better grade in the future.
This quarter, it could be related to the concept intercultural awareness by is that we had nothing to do with intercultural awareness. Tho, we showed respect to the teacher, submitting on time. We treated the equipments properly and neatly this quarter and that we had a great time.