Liquids and Boiling Point Elevation Questions

1. What were the changes that you noticed?

Unfortunately, we were not able to complete this lab, and therefore did not see any changes. When we boiled the 200 mL of water without NaCl, we obtained a boiling point of 99.8 degrees Celsius. This result is very close to the boiling point that was expected. However, due to the time constraint, we were not able to get past this first step, as we were midway through adding NaCl when we were forced to stop. If we were able to continue this experiment, we should have noticed that the boiling point increased as more NaCl was added. 

2. What were your results compared to the other groups?

Although many groups did not get to finish, the groups who completed the experiment saw an increase in the boiling point as more NaCl was added. However, there were one or two groups whose boiling point decreased or stayed the same. This was very interesting, as ideally, the boiling point would increase as more NaCl was added. Due to the environment that we are in, there are many variables that could result in the decrease of the boiling point. For example, the time after boiling point when the temperature was recorded. Some groups recorded their temperature just as the water was brought to a boil, while some recorded the temperature after the boiling had continued for a few minutes. Furthermore, the amount of water and the amount of salt could have varied from group to group, resulting in these changes that ultimately affected the outcome of the experiment. 

3. What were the relative differences?

See question number 2 (above). 

4. As you doubled the amount of solute, what was the relative change in boiling point?

Although we did not get to this point in the experiment, we can hypothesize that as we doubled the amount of solute, the boiling point would increase. However, the boiling point would most likely not double. Judging from the results of the other groups, the boiling point would only increase by a little less than 2%. It would be interesting to see if the change in boiling point is linear or non-linear if we doubled the salt again. Although there are many independent variables, there should be some relationship between the amount of NaCl added and the increase in boiling point. It would be interesting to see what our increase in boiling point would have been if we had been able to complete the experiment. 

How Much Water/How Much Salt?

Samantha Karp
3/12/09
Lab Report
How much Water and How much Salt?
Introduction:
When we were first presented with this experiment, I was excited to discover the results, although I was a little bit confused about where we were supposed to begin. This experiment, which produced common table salt, was conducted over the course of several days. The assignment was to make a procedure given the molarity, formula, reactants, and products, along with our previous knowledge, and determine the amount of water from the reaction. When we first began the experiment, we were told that we needed to find how much water not only from the reaction, but also from the reactants. Later in the experiment, this was changed to simply finding the water from the reaction. We were told that the molarity of the NaOH solution was 3M and the molarity of the HCl was 12 M. The products of NaOH and HCl are H2O +NaCl. We needed to use our knowledge of neutrality in order to neutralize the solution. Since we were not given a procedure, as we normally are, the first day or two was devoted to simply discovering what steps we were supposed to take. When we first began, we thought that we needed to separate the NaOH and HCl and boil them separately before combining them. However, we were later told that those steps were not necessary. The formulas that we had to use were only necessary for calculating the final results. That formula was C=mol/L, with C being concentration, mol meaning moles, and L meaning liters. Although our hypothesis did not include the exact mass of the water, we predicted that there would be more water than salt. This experiment was very challenging at first, although it proved to be very interesting towards the end.

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 stochiometry.

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

Methods:
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 are after we realized that the initial solution was not neutral. This is the amount of acid/base that we added to the first solution.
Note: On Word, this is in a chart. Look at the numbers as if it were on a chart. Read vertically. Example (first column): Added 2 drops of acid, 0 drops of base, result=dark blue=too basic.

Mass of drops (g):
0.0207 g(1 drop)
0.0341 g(2 drops)
0.0648 g(3 drops)
0.0889 g(4 drops)
Average mass of 1 drop:0. 0112 g

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=  4mL of 3M NaOH + 1 mL of 12M HCL-->NaCl +H2O

C=mol/v    mol=cv

HCl=(12M)(0.001)=0.012 moles

NaOH=(3M)(0.004)=0.012 moles

0.012 mol NaCl x 58.44=0.7 grams=Theoretical (under perfect conditions)

0.3266=Actual=Experimental yield 

% yield=Actual/Theoretical x 100

0.3266 g/0.7 x 100=46.66%

Discussion/Analysis:
Our hypothesis, which was that the amount of water would be greater than the amount of salt, was proven correct. Although some of our water spilled out of the crucible, our hypothesis was still proven, as the mass of the NaCl was 0.3226 grams while the mass of the H2O was 4.92 grams. However, the second part of our hypothesis, which was that the solution would be neutral the first time we combined it, was not correct. We made four more attempts at achieving a neutral point by adding drops of acid or base, depending on what color the pH paper turned. Although we did have to try four times, when the pH paper turned red, we only had to add three more drops. Drops do not have a lot of volume, and we knew that we would only have to add a small amount of acid or base in order to achieve neutrality, since we did not measure out a large quantity of volume at the beginning of the experiment. Furthermore, the moles of base are not exactly equal to the moles of acid. This is due to the margin of error. The NaOH is not new, so it has absorbed more water due to this fact. Also, other people left the NaOH open, which caused it to be exposed to the air. Saying this, our moles of acid compared to our moles of base are very close nonetheless. Additionally, we had to revise our procedure many times before we got our final product. The first class in which we were presented with this experiment we simply thought of ideas on how to approach this experiment. Our first idea was too arithmetical, and Mr. Schoudel wanted us to find the results by experimentation. This led to us revising our procedure once again. Furthermore, we used our knowledge from the alcohol fermentation lab that we observed earlier in the year. We knew that in that experiment, Mr. Schoudel boiled out the alcohol, which is something very similar to what we wanted to do. If we had a more accurate procedure from the beginning of the experiment, we could have performed it more efficiently. However, there were many obstacles and challenges that we had to overcome, as this was the first time we were presented with a lab without a procedure. Although I am very pleased with how the experiment turned out, there would be some improvements that I would make. First, I would place the flame over the crucible filled with solution more slowly. Although we tried our best to do this, we held the flame under the crucible for just a moment too long, which caused a tiny bit of water to spill out of the crucible. Although it was just a small amount of water, it still changed the outcome of the experiment. Also, I would move more efficiently the next time. Although we did finish the experiment, we had to stay after class for around five more minutes. If we had known exactly what we had to do, we could have been more efficient. Finally, I would make sure that we made all of our measurements on the analytical balance. Although we made the majority of them on the analytical balance, we used a regular balance for two or three measurements. Since science is such a precise subject, every decimal place counts. There is a great margin for error in every experiment we perform, as we are subjected to many different variables, such as the old NaOH. These are variables that we cannot control, so we have to do our best to work around them. Although I could make changes, I am extremely pleased with the way we executed the experiment.

Conclusion
This experiment was exciting, interesting, and challenging for me. I never knew that we could produce table salt so easily. This experiment was interesting, as I really wanted to discover the results and answers to the experiment. Getting around the different obstacles was challenging, but we were able to perform a great experiment. This experiment used our previous knowledge and the information that we are learning and forced us to think critically about it. I can say that I understand more about products and reactants, neutrality, and other topics than I did before. Once our procedure was completed, the experiment was much less challenging. However, making us create our own procedure was another step and another obstacle. I think that we handled the experiment very well, and really applied the chemistry knowledge that we had. Although I was a little concerned at first about the experiment, as I did not know how it was going to go, I enjoyed performing this experiment very much.

3/3-Lab Procedure-How Much Water/Salt?

Samantha Karp
3/3/09
Lab Procedure

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 we 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.


Questions to Ask in Class:
Will the glass burn if it is under the burner?
Do we need to collect the steam?

Density/Buoyancy Lab Report

Samantha Karp
9/24/08
Density and Buoyancy Lab
Introduction:
When first presented with the experiment, I was excited to begin, as I was wondering what the outcome would be. This experiment, which tested density, was conducted over the course of several days. The assignment was to discover the necessary density of the vial in order for it to stay in the middle of the two types of water. The water had different temperatures, as one was frigid salt water, and one was warm tap water. The warm tap water was dyed blue with food coloring, as to see the separation between the water more clearly. The warm tap water was on top of the salt water, as it had a lower density. We were told that the salt water had a density that was greater than one, and the tap water had a density of less than one, but we were not given the exact densities. In order to perform this experiment, we had to use the density formula. The density formula is mass per unit volume, represented by D=m/V, with D being density, m being mass, and V being volume. We hypothesized that the density had to be one, so it could remain in the middle. This experiment was very interesting and exciting to perform.

Hypothesis:
We hypothesized that the vial needed to have a density of around one, as the two types of water had densities greater than one and less than one. Furthermore, we knew that we had to fill the vial with either salt or sand, in order to have the vial remain in the middle. We made this hypothesis using the density formula and the variables that were given.

Materials:
• 1 graduated cylinder
• 1 fish tank
• 1 balance
• 2 vials
• Warm tap water
• Cold salt water
• Blue food coloring
• Sand
• Table Salt
• Pencil
• Paper
• Calculator

Methods
1. Gather all the materials
2. Get the salt water and measure out the desired amount
3. Get the warm tap water and measure out the desired amount
4. Using the blue food coloring, dye the warm tap water blue
5. Put both the salt water and the tap water into the fish tank, they should separate into two layers, with the salt water being on the bottom.
6. Fill the graduated cylinder with water. Do not fill it all the way up, but simply fill it up to about halfway. We filled it up to 52.3 mL.
7. Record the amount of water that was put in the graduated cylinder
8. Get the vial and put some sand in it. You may measure and record the amount of sand that is put into the vial, if desired. A good amount is around 13.0 mL of sand.
9. Place the vial with the sand into the graduated cylinder.
10. Record how much the water rises.
11. Subtract the value from step ten from the initial value of water that was put into the graduated cylinder. Record the results. This is the volume of the vial.
12. Measure and place some sand into the vial. Record how much sand was put into the vial.
13. Measure the mass of the sand and the vial using the balance. Record the results.
14. Divide the calculation from step 13 by the volume of the vial, which is step 11. This will give you the density.
15. If the density is very close to or at one, place the vial into the fish tank. Record the results.
16. If the vial was resting in the middle of the fish tank, record the data and share your results.
17. If the vial sunk or float, repeat steps 12-16, until the vial is resting in the middle.
18. Record and analyze all of the data.

Data/Results
Volume of the Vial: 52.3 mL=initial amount of water in the graduated cylinder
76.8 mL=terminal amount of water in the graduated cylinder
76.8mL-52.3mL=24.5ml=Volume of the vial
Density
Amount of Sand (mL) 13.0 11.9 12.7 12.25 12.5 12.6 12.8
Mass (g) 26.4 24.49 24.6 24.55 25.62 24.77 24.8894
Density (g/cm3) 1.077 .999 1.004 1.002 1.046 1.011 1.0158

The last number in the table, with a mass of 24.8894, was the vial that stayed in the middle. We used 12.8 mL of sand, which gave us a density of 1.0158. This was the second closest that we came to getting a density of 1, which was our goal. Even though we had a density that was 1.011, which was the closest to one, that vial still rose to the top of the water. However, even though it wasn’t exactly one, the final vial was still resting in the middle of the two types of water.

Discussion/Analysis
Our hypothesis, which was that we needed to get a density close to or around one, was proven correct. Although the vial that worked was not the closest to one, as there was another number that was closer to one, it still proves our hypothesis. Although we had to try numerous times, we were always very close to our goal density of one. The farthest density from one that we got was 1.077, which was the first value that we tested. Additionally, none of our vials sank. The vials that did not work were always too light, and we needed to add more sand, since the vials were floating to the top. We were hesitant to add a lot more sand to the vial, as we preferred that it did not sink. This would explain why all of our measurements are very close together, because the amount of sand that we added was very small. Although I am very pleased with how the experiment turned out, there would be some improvements that I would make. First, I would have recorded my notes on a neater sheet of paper, in a neater fashion. However, my results are still shown, but I would prefer a neater sheet next time. Furthermore, I would measure the amounts more carefully. Because science is an exact subject, all the measurements need to be precise, as a tenth of a decimal can make a difference. Finally, I would be more hesitant to put the first vial in the fish tank, and make sure that all the measurements were exactly how I wanted them. Although I would make these changes, I am very pleased with the way we executed the experiment.

Conclusion
This experiment was both interesting and challenging for me. It was interesting because I was excited to know what the answer to the experiment was, and I could not wait to get the result. However, determining the exact amount of sand to put in was challenging. This experiment made us think critically about what we needed to do, and how we could use the variables that were given, along with our prior knowledge. Once we knew how to perform the experiment, it was much less challenging. I enjoyed performing this experiment very much.