1. What were the changes that you noticed?
Unfortunately, we were not able to complete this lab, therefore we could not analyze the different solutions to see any changes. When we boiled the 200 mL of water without salt, we obtained a boiling point of 99.8 degrees Celsius. Our boiling point was a very similar to our hypothesized boiling point of 100 degrees Celsius. We began the second step of adding salt
(NaCl) to our solution, however due to time constraint we had to stop in the middle of boiling our solution. We presume that the boiling point would increase from step one.
2. What were your results compared to the other groups?
In the first step of the lab, most groups had around the same boiling point between 95 and 100 degrees Celsius. As we continued the experiment many groups had a steady change in temperature, usually increasing a few degrees. However, there were one and two groups whose boiling points decreased or remained the same. This was interesting, as ideally, the boiling point should only increase a few degrees. There were many factors that determined the increases and decreases of temperature, such as amount of water added, NaCl added, and the boiling point of the solutions. Overall, most groups had a steady increase in temperature in each step of the experiment.
3. What were the relative differences?
Refer to question #2
4. What was the relative change in boiling point?
Our group did not reach this step in the lab due to time constraint. However, our hypothesis based on other groups' work would be that the temperature would increase a few degrees if we doubled the amount of solute. It would have been interesting to evaluate the changes in boiling point if we doubled the amount of solute.
Wednesday, April 29, 2009
Thursday, March 12, 2009
NaOH and HCl Lab
Jennifer Wilson
Chemistry 201-2
Mr. Schoudel
Given: 3M NaOH (aq) + 12M HCl (aq) → H2O + NaCl
How much water and how much salt?
Water: From the reaction
Introduction:
Our class has performed many interesting experiments, however we recently worked with dangerous acid and base solutions in an experiment to find the amount of water in a reaction. We were provided the equation above and the materials to accurately carry out the experiment. This experiment was very challenging, as we had to form our own methods and procedures. My partner, Samantha and I were unsure of how to approach the experiment, as we do not usually create our own procedures. We did have some knowledge of separating two aqueous solutions from an alcohol fermentation demonstration earlier in the year. While forming our own procedures was very challenging, it made us feel more in control of the experiment and at least for me, a closer connection to the lab. We did not have a set of directions; therefore we could alter our steps at any point during the procedure, which gave us more flexibility when finding the overall result. We made many revisions to our procedure, as the requirements for the experiment changed and we discovered new ways to reach the final result. After making these revisions, we finally devised a solid set of procedures that would hopefully lead us to the final result. Unlike past experiments that involved materials, such as water, sand or even a lollipop, we were using dangerous acid and base aqueous solutions. Although, we were nervous if we were forming the most accurate methods and did have a few mishaps here and there, our experiment was carried out well, which ultimately found us our unknown. This experiment was more challenging that usual labs, however the difficulty of the lab made it more interesting and informative.
Hypothesis:
We hypothesized that there would be a greater amount of water than salt, although we were not exactly positive why that would be the case. Furthermore, we believed that the solutions would be neutral when we first combined them, as we would measure the appropriate amounts. We knew that we had to boil the water out in order to find the amount of salt, and consequently, the amount of water. Additionally, we used the knowledge that we gained from the alcohol fermentation experiment that was demonstrated earlier in the year. From this experiment, we knew we needed to boil out one of the components in order to find the other. We made these hypotheses based on our knowledge of neutrality and stoichiometry.
Materials:
• NaOH
• HCl
• 2 small graduated cylinders
• 1 glass rod
• 2 100 mL beakers
• 1-2 pipettes
• 1 roll of paper towels
• 1 analytical balance
• 1-2 strips of pH paper
• Calculator
• Pencil
• Paper
• 1 Bunsen burner
• 1 stand
• 1 wire mesh square
• 1 starter/lighter
• 1 crucible and top
• Clock
• Baking soda
• Vinegar
• 1 pair of tongs
• 1 clear, plastic tray
Procedure:
1.Gather all supplies and materials necessary for the experiment.
2. Measure out 4 mL of the 3M NaOH and 1 mL of the 12M HCl into separate graduated cylinders. However, finding these precise measurement will be very difficult. To make this process easier, pour around 10 mL of each solution into a separate beaker. To make sure that the solution does not run down the side of the container, place a glass rod in the center of the beaker. Using a pipette, drop the correct amount of acid or base into the graduated cylinder. For the HCl, be sure to measure it out under the hood, as it will produce a cloud.
3. Find the mass of a 100 mL empty beaker. Record this number.
4. Pour the two solutions into the beaker. Using the glass rod, place a drop of the solution onto the pH paper. If the pH paper does not turn green, add the necessary amounts of acid or base. Record all information.
5. Using a pipette and an analytical balance, find the mass of one drop from the pipette. Take more than one sample and then calculate the average. Using the density formula, determine the volume of one drop.
6. Find the mass of the beaker. Find the mass of the solution. Record all information.
7. Set up the burner and all necessary materials for the later step.
8. Place the empty crucible on top of the burner and allow the flame to pass over it for 5 minutes. This will purify the crucible. Allow the crucible to cool for around 2-3 minutes.
9. Find the mass of the empty crucible.
10. Pour the neutral solution into the crucible.
11. Using a burner, place the crucible above the flame. Pass the flame gently over the crucible. Check the amount of water every minute or so to see how much water is left. When there is only white salt and no water left, turn the burner off. This will eventually evaporate the water out, leaving only the salt. Allow the crucible to cool.
12. Find the mass of the salt by finding the mass of the crucible. Record these results.
13. Subtract the amount of salt from the total mass. This will give you the amount of water.
14. Record your results and data.
15. Clean up all materials and workspace. When pouring out the solutions, you must neutralize them. For the acid solution, or HCl, pour a little bit of baking soda into the graduated cylinder/beaker. For the base solution, or NaOH, pour a little bit of vinegar into the graduated cylinder/beaker. This will neutralize the solutions and make them safe to go down the drain.
*If you are not completing your experiment in one sitting, cover the acid and base to ensure accurate results.
Data/Results:
# Of drops of acid Added 2 drops Added 5 drops Added 10 drops Added 0 drops
# Of drops of base Added 0 drops Added 0 drops Added 0 drops Added 3 drops
Color/Is it neutral? Dark blue= too basic Blue= too basic Red= too acidic Light green= neutral
*Note: These numbers were the amounts added we realized that the initial solution was not neutral. This is the amount of acid/base that we added to the first solution.
Mass of drops:
(1 drop) 0.0207 grams
(2 drops) 0.0341 grams
(3 drops) 0.0648 grams
(4 drops) 0.0889 grams
Average mass of 1 drop: 0. 0112 grams
Density=Mass/Volume
Density of water=1
Mass of drop=0.0112
1=0.0112/V
V= 0.0112 mL (1 drop)
Mass of empty graduated cylinder=25.93 g
Mass of empty beaker=50.83 g
Mass of beaker with neutral solution=56.0763 g
Mass of solution=56.0763-50.83=5.2463 g
Mass of empty crucible=15.5217 g
Mass of crucible after heating=15.8483 g
Amount of NaOH used=0.0121 moles=0.48 g
- 3M=moles/L
- 0.0112 x 3=0.0336 grams
- 4 mL + 0.0336=4.0336
- 4.0336/1000=0.0040336 L
- 3M=moles/0.0040336
- Moles=0.0121
- 0.0121 x 40=0. 48 g
Amount of HCl used=0.014 moles= 0.52 g
- 12M=moles/L
- 0.0112 x 17=0.1904 g
- 1 mL + 0.1904=1.1904
- 1.1904/1000=0.0011904 L
- 12M=moles/0.0011904
- Moles=0.014
- 0.014 x 36.458=0.52 g
Mass of NaCl at the end of the experiment=15.8483-15.5217=0.3266 g
0.3266 g/58.44=0.006 moles
Mass of H2O at the end of the experiment=5.2463-0.3266=4.92 g
4.92 g/ 20.16= 0.24 moles
Actual/Theoretical Yield:
Theoretical Yield= 3M NaOH + 12M HCl --> NaOH + H2O
Concentration= Mol/Volume
Mol= CV
HCl (12M)(0.001)= 0.012 Mol
NaOH (3M)(0.004)= 0.012 Mol
Mol --> Grams
0.012 Mol NaOH x 58.44 g/ 1 Mol NaOH = 0.7 g (Under perfect conditions)
% Yield= Actual/ Theoretical x 100
0.3266 g/ 0.7 g x 100 = 46.66 %
0.3266 g= Experimental Yield
Discussion/Analysis:
We hypothesized that there would be a greater amount of water than salt, although we were not exactly positive why that would be the case. Furthermore, we believed that the solutions would be neutral when we first combine them, as we would measure the appropriate amounts. We knew that we had to boil the water out in order to find the amount of salt, and consequently, the amount of water. We knew we needed to boil out one of the components in order to find the other. This was a step in the right direction, however I believe we made it more complicated than the experiment actually was. It was difficult to know if we were actually in the right direction because we had devised our own procedures that could possibly result in something very dangerous. Fortunately, everyone was safe and productive during this experiment, so that no group had any accidents with an acid or base solution. During our experiment we reached the point were we had to test if our solution was neutral. We used pH paper to determine the neutrality of the solution. On our first attempt, we were left with a blue drop on the paper, which signified that the solution was too basic. Therefore we added five more drops of acid, which formed another blue drop on the opposite side of the paper. We rushed the next step in our experiment and added ten drops of acid to reach a reddish dye on the paper. Now the solution was too acidic. Next time I think it is important that if we find ourselves frustrated that the solution is not changing, we add smaller amounts of the necessary acid or base, therefore we are more efficient. We finally added three more drops of base to finally neutralize our solution. We continued with our experiment and made many measurements and weight calculations to help determine our final mass of water in the reaction. Something to remember for next experiment is to work efficiently, but neatly as well. I think it would have helped our group if we worked at a more rapid pace, yet still maintained the neatness and accuracy when making measurements and calculations.
Conclusion:
The NaOH and HCl lab was a new and informative way of learning about neutrality and stoichiometry. The lab was different in the sense that we had to devise our own procedures and follow our methods, even if they were not accurate. This was one of the major challenges that my group had while performing this experiment. We were unsure if we were accurately testing the amount of water remaining in the reaction. Although this was a large obstacle to overcome right from the start of the experiment, we made some very tactful decisions and measurements that helped us to form our final answer. Furthermore, the materials and information given was very limited which made this experiment even more challenging. Once we reached the point that we knew our procedures were somewhat correct, we began to relax and try to carry out the experiment as efficiently as possible. With the exception of a few mishaps, Sam and I were able to follow through with our experiment to find what we hope to be the most accurate answer. This experiment was different from other experiments, as I felt we were more flexible with the procedures and could determine the results with our methods. I enjoyed the opportunity to devise our own procedures and follow through with an interesting experiment.
Chemistry 201-2
Mr. Schoudel
Given: 3M NaOH (aq) + 12M HCl (aq) → H2O + NaCl
How much water and how much salt?
Water: From the reaction
Introduction:
Our class has performed many interesting experiments, however we recently worked with dangerous acid and base solutions in an experiment to find the amount of water in a reaction. We were provided the equation above and the materials to accurately carry out the experiment. This experiment was very challenging, as we had to form our own methods and procedures. My partner, Samantha and I were unsure of how to approach the experiment, as we do not usually create our own procedures. We did have some knowledge of separating two aqueous solutions from an alcohol fermentation demonstration earlier in the year. While forming our own procedures was very challenging, it made us feel more in control of the experiment and at least for me, a closer connection to the lab. We did not have a set of directions; therefore we could alter our steps at any point during the procedure, which gave us more flexibility when finding the overall result. We made many revisions to our procedure, as the requirements for the experiment changed and we discovered new ways to reach the final result. After making these revisions, we finally devised a solid set of procedures that would hopefully lead us to the final result. Unlike past experiments that involved materials, such as water, sand or even a lollipop, we were using dangerous acid and base aqueous solutions. Although, we were nervous if we were forming the most accurate methods and did have a few mishaps here and there, our experiment was carried out well, which ultimately found us our unknown. This experiment was more challenging that usual labs, however the difficulty of the lab made it more interesting and informative.
Hypothesis:
We hypothesized that there would be a greater amount of water than salt, although we were not exactly positive why that would be the case. Furthermore, we believed that the solutions would be neutral when we first combined them, as we would measure the appropriate amounts. We knew that we had to boil the water out in order to find the amount of salt, and consequently, the amount of water. Additionally, we used the knowledge that we gained from the alcohol fermentation experiment that was demonstrated earlier in the year. From this experiment, we knew we needed to boil out one of the components in order to find the other. We made these hypotheses based on our knowledge of neutrality and stoichiometry.
Materials:
• NaOH
• HCl
• 2 small graduated cylinders
• 1 glass rod
• 2 100 mL beakers
• 1-2 pipettes
• 1 roll of paper towels
• 1 analytical balance
• 1-2 strips of pH paper
• Calculator
• Pencil
• Paper
• 1 Bunsen burner
• 1 stand
• 1 wire mesh square
• 1 starter/lighter
• 1 crucible and top
• Clock
• Baking soda
• Vinegar
• 1 pair of tongs
• 1 clear, plastic tray
Procedure:
1.Gather all supplies and materials necessary for the experiment.
2. Measure out 4 mL of the 3M NaOH and 1 mL of the 12M HCl into separate graduated cylinders. However, finding these precise measurement will be very difficult. To make this process easier, pour around 10 mL of each solution into a separate beaker. To make sure that the solution does not run down the side of the container, place a glass rod in the center of the beaker. Using a pipette, drop the correct amount of acid or base into the graduated cylinder. For the HCl, be sure to measure it out under the hood, as it will produce a cloud.
3. Find the mass of a 100 mL empty beaker. Record this number.
4. Pour the two solutions into the beaker. Using the glass rod, place a drop of the solution onto the pH paper. If the pH paper does not turn green, add the necessary amounts of acid or base. Record all information.
5. Using a pipette and an analytical balance, find the mass of one drop from the pipette. Take more than one sample and then calculate the average. Using the density formula, determine the volume of one drop.
6. Find the mass of the beaker. Find the mass of the solution. Record all information.
7. Set up the burner and all necessary materials for the later step.
8. Place the empty crucible on top of the burner and allow the flame to pass over it for 5 minutes. This will purify the crucible. Allow the crucible to cool for around 2-3 minutes.
9. Find the mass of the empty crucible.
10. Pour the neutral solution into the crucible.
11. Using a burner, place the crucible above the flame. Pass the flame gently over the crucible. Check the amount of water every minute or so to see how much water is left. When there is only white salt and no water left, turn the burner off. This will eventually evaporate the water out, leaving only the salt. Allow the crucible to cool.
12. Find the mass of the salt by finding the mass of the crucible. Record these results.
13. Subtract the amount of salt from the total mass. This will give you the amount of water.
14. Record your results and data.
15. Clean up all materials and workspace. When pouring out the solutions, you must neutralize them. For the acid solution, or HCl, pour a little bit of baking soda into the graduated cylinder/beaker. For the base solution, or NaOH, pour a little bit of vinegar into the graduated cylinder/beaker. This will neutralize the solutions and make them safe to go down the drain.
*If you are not completing your experiment in one sitting, cover the acid and base to ensure accurate results.
Data/Results:
# Of drops of acid Added 2 drops Added 5 drops Added 10 drops Added 0 drops
# Of drops of base Added 0 drops Added 0 drops Added 0 drops Added 3 drops
Color/Is it neutral? Dark blue= too basic Blue= too basic Red= too acidic Light green= neutral
*Note: These numbers were the amounts added we realized that the initial solution was not neutral. This is the amount of acid/base that we added to the first solution.
Mass of drops:
(1 drop) 0.0207 grams
(2 drops) 0.0341 grams
(3 drops) 0.0648 grams
(4 drops) 0.0889 grams
Average mass of 1 drop: 0. 0112 grams
Density=Mass/Volume
Density of water=1
Mass of drop=0.0112
1=0.0112/V
V= 0.0112 mL (1 drop)
Mass of empty graduated cylinder=25.93 g
Mass of empty beaker=50.83 g
Mass of beaker with neutral solution=56.0763 g
Mass of solution=56.0763-50.83=5.2463 g
Mass of empty crucible=15.5217 g
Mass of crucible after heating=15.8483 g
Amount of NaOH used=0.0121 moles=0.48 g
- 3M=moles/L
- 0.0112 x 3=0.0336 grams
- 4 mL + 0.0336=4.0336
- 4.0336/1000=0.0040336 L
- 3M=moles/0.0040336
- Moles=0.0121
- 0.0121 x 40=0. 48 g
Amount of HCl used=0.014 moles= 0.52 g
- 12M=moles/L
- 0.0112 x 17=0.1904 g
- 1 mL + 0.1904=1.1904
- 1.1904/1000=0.0011904 L
- 12M=moles/0.0011904
- Moles=0.014
- 0.014 x 36.458=0.52 g
Mass of NaCl at the end of the experiment=15.8483-15.5217=0.3266 g
0.3266 g/58.44=0.006 moles
Mass of H2O at the end of the experiment=5.2463-0.3266=4.92 g
4.92 g/ 20.16= 0.24 moles
Actual/Theoretical Yield:
Theoretical Yield= 3M NaOH + 12M HCl --> NaOH + H2O
Concentration= Mol/Volume
Mol= CV
HCl (12M)(0.001)= 0.012 Mol
NaOH (3M)(0.004)= 0.012 Mol
Mol --> Grams
0.012 Mol NaOH x 58.44 g/ 1 Mol NaOH = 0.7 g (Under perfect conditions)
% Yield= Actual/ Theoretical x 100
0.3266 g/ 0.7 g x 100 = 46.66 %
0.3266 g= Experimental Yield
Discussion/Analysis:
We hypothesized that there would be a greater amount of water than salt, although we were not exactly positive why that would be the case. Furthermore, we believed that the solutions would be neutral when we first combine them, as we would measure the appropriate amounts. We knew that we had to boil the water out in order to find the amount of salt, and consequently, the amount of water. We knew we needed to boil out one of the components in order to find the other. This was a step in the right direction, however I believe we made it more complicated than the experiment actually was. It was difficult to know if we were actually in the right direction because we had devised our own procedures that could possibly result in something very dangerous. Fortunately, everyone was safe and productive during this experiment, so that no group had any accidents with an acid or base solution. During our experiment we reached the point were we had to test if our solution was neutral. We used pH paper to determine the neutrality of the solution. On our first attempt, we were left with a blue drop on the paper, which signified that the solution was too basic. Therefore we added five more drops of acid, which formed another blue drop on the opposite side of the paper. We rushed the next step in our experiment and added ten drops of acid to reach a reddish dye on the paper. Now the solution was too acidic. Next time I think it is important that if we find ourselves frustrated that the solution is not changing, we add smaller amounts of the necessary acid or base, therefore we are more efficient. We finally added three more drops of base to finally neutralize our solution. We continued with our experiment and made many measurements and weight calculations to help determine our final mass of water in the reaction. Something to remember for next experiment is to work efficiently, but neatly as well. I think it would have helped our group if we worked at a more rapid pace, yet still maintained the neatness and accuracy when making measurements and calculations.
Conclusion:
The NaOH and HCl lab was a new and informative way of learning about neutrality and stoichiometry. The lab was different in the sense that we had to devise our own procedures and follow our methods, even if they were not accurate. This was one of the major challenges that my group had while performing this experiment. We were unsure if we were accurately testing the amount of water remaining in the reaction. Although this was a large obstacle to overcome right from the start of the experiment, we made some very tactful decisions and measurements that helped us to form our final answer. Furthermore, the materials and information given was very limited which made this experiment even more challenging. Once we reached the point that we knew our procedures were somewhat correct, we began to relax and try to carry out the experiment as efficiently as possible. With the exception of a few mishaps, Sam and I were able to follow through with our experiment to find what we hope to be the most accurate answer. This experiment was different from other experiments, as I felt we were more flexible with the procedures and could determine the results with our methods. I enjoyed the opportunity to devise our own procedures and follow through with an interesting experiment.
Tuesday, March 3, 2009
Lab Procedure
Jennifer Wilson
Chemistry 201-2
3/3/09
Given: 6M NaOH (aq) + 12M HCl (aq) → H2O + NaCl
How much water and how much salt?
Water:
1. From the reaction
2. From the reactants, already have the water
Procedure
1. Measure out 50 mL of the 6M NaOH and 100 mL of the 12M HCl in a graduated cylinder.
2. Find the mass of two empty Erlenmeyer flasks. Record these amounts. Label the Erlenmeyer flasks.
3. Pour the 50 mL of the NaOH solution into the Erlenmeyer flasks.
4. Find the mass of the solution. Record this amount.
5. Using a hot plate or a burner, place the Erlenmeyer flask full of the NaOH solution above the flame. This will eventually evaporate the water, leaving only the NaOH.
6. Find the mass of the NaOH. Record these results.
7. Subtract the mass of the NaOH from the mass that was found in step 4. This will give you the amount of water that is in the solution.
8. Repeat steps 3-7 with the HCl solution.
9. Repeat step 1.
10. Pour the two solutions into another Erlenmeyer flask. Shake until dissolved.
11. Find the mass of the solution.
12. Using a hot plate or a burner, place the Erlenmeyer flask above the flame. This will eventually evaporate the water out, leaving only the salt.
13. Find the mass of the salt. Record these results.
14. Subtract the amount of salt from the total mass. This will give you the amount of water.
15. Record your results and data.
Chemistry 201-2
3/3/09
Given: 6M NaOH (aq) + 12M HCl (aq) → H2O + NaCl
How much water and how much salt?
Water:
1. From the reaction
2. From the reactants, already have the water
Procedure
1. Measure out 50 mL of the 6M NaOH and 100 mL of the 12M HCl in a graduated cylinder.
2. Find the mass of two empty Erlenmeyer flasks. Record these amounts. Label the Erlenmeyer flasks.
3. Pour the 50 mL of the NaOH solution into the Erlenmeyer flasks.
4. Find the mass of the solution. Record this amount.
5. Using a hot plate or a burner, place the Erlenmeyer flask full of the NaOH solution above the flame. This will eventually evaporate the water, leaving only the NaOH.
6. Find the mass of the NaOH. Record these results.
7. Subtract the mass of the NaOH from the mass that was found in step 4. This will give you the amount of water that is in the solution.
8. Repeat steps 3-7 with the HCl solution.
9. Repeat step 1.
10. Pour the two solutions into another Erlenmeyer flask. Shake until dissolved.
11. Find the mass of the solution.
12. Using a hot plate or a burner, place the Erlenmeyer flask above the flame. This will eventually evaporate the water out, leaving only the salt.
13. Find the mass of the salt. Record these results.
14. Subtract the amount of salt from the total mass. This will give you the amount of water.
15. Record your results and data.
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