UTF-8Template for Final ExamTemplate for Chem 352 Final Exam
Save this final as "Last_Name_Final_Exam." Save the simulation in the ORIGINAL state, with instructions on how to run it (what variables to change)
and a description of the observed results, how you interpret them, and the conclusions you draw from the results to answer the original question.
The first part of the assignment is to choose a question to investigate that meets two criteria:
1. It is interesting and addresses an issue you want to learn more about by conducting a computer experiment.
2. It is specific enough to be doable -- to be able to construct a set of simple simulations in which you can investigate
the effects of specific variables one at a time (for example, mass, intermolecular forces, size of particles, temperature etc.).
Your Name:{__________Heather Merritt__________________}
1. State the Question you are investigating:
{ How do electrons move in the presence of a magnetic field based on their mass?
}
2. Explain why this quesion is interesting:
{For me, the idea of a varying path of ions based on their molecular weight while in the presense of magnetic fields is interesting because it is the basis of how the mass of an ion is found when using mass spectrometry. The magnetic field will curve the path of an ion to a certain extent. This extent can be varied by changed the strength of the magnetic field and the size of charge of the ion. So, I find it interesting to see exactly how changing the mass of an ion will affect the path it travels due to a magnetic field.
}
3. Explain why this quesion is specific enough to be testable with simulation so as to give a definite answer.
{This is a very specific question in that there is only one changing variable (mass) and everything needed to set up the simulation and answer the question (magnetic field, ions, etc) can be found in the sumulator. In addition, the relative amount of variance between an ion of greater mass and an ion of weaker mass can be found using the coordinates of the ion particles at different points in time.
}
4. Describe your reasoning in building the simulation the way you did, the testing you did, and changes you
had to make to make it work.
{ I started off by adding a magnetic field to each side and place a negatively charged particle into the simulator. After it did not move, I remembered that a particle, in order to be affected by a magnetic field, must have a starting velocity. Therefiore, I gave it a small y-velocity of one m/s. This did not seem to make much of an impact on the ions so I increased the y-velocity to 1000. I gave one ion a mass of 60 and another 120 g/mol. However, at a mass of 120, the circles created by the magnetic field are two large for the simulation box, and the path of the ion was disrupted by the walls. So, I settled on an ion with a smaller radius with molecular masses of 80 and 40 g/mol.
}
5. What variables will stay fixed for the experiment and how did you choose the values for those variables?
{The variables that will stay fixed will be the direction and magnitude of the magnetic field. I just picked a direction for the field, but the magnitude was chosen so that the molecules would not hit the wall. In addition, the charge and radius of the ions will not change. I picked a radius that would be the most favorable to not hitting the walls during the simulation and the charge of -1 was given so that the magnetic field would make an impact on the ions, as neutral particles are not affected by magnetic fields. The starting positions and starting velocities of the particles will remain consistant but will vary from their intitial value, as this is what happens when moving ions are impacted by a magnetic field: they accelerate and change position.
}
6. What variable will you change to answer the question? Over what range of values will you test the effect of the variable?
{I will change only the mass of each of the ions used in the experiment. I will be testing 80 g/mol and 40 g/mol. I would add another at a higher mass, but I cannot place another simulation in the window.
}
7. What variables will you monitor or measure? How will you output or measure them? Examples of variables we
have output include the volume, the temperature (or average KE), the total energy, the potential energy, the arrangements of
particles, etc.
{ I want to figure out the radius of the circle that the ion will make. I will do this by measuring the change in position or Pf-Pi of the two ions' paths once they reach the farthest point from the initial position. I will do this by letting the simulation run until the molecules made a little more than a complete circle. Then, I will move the time bar until the the position of the ion goes back to the initial position after it had completed its first circle. I will take that time point and divide it by 2 and go to that time, which is where the ion had made half of the circle and therefore is farthest away from its initial position. I will take the x and y values from this and subtract the x and y compontents from the initial position from them to get a vector sum for the change in position. I will then combine the x and y components and this will be the diameter of the circle. Dividing this number by two will give the radius. With this information, I can compare the mass of the particle to the radius of the circle it makes.
}
8. Usually you need to equilibrate your simulation before running to measure results. Will you equilibrate your simulation with the heat bath on (Isothermally) or without the heat bath -- i.e. Adiabatically? Explain.
{I will not need to equilibrate my simulation because there is only one molecule in it.
}
9. When you actually run the simulation -- will you do it with the heat bath on or off? Explain.
{I will not put a heat bath on it because, as I found, it causes the ions to follow the same path with a different velocity. Therefore, it is impeding on the study, and it not needed anyways for the measurements I will be collecting. Although the heat of the system does increase to a point where it is too much for the system to handle, my measurements do not require the simulation to run that long and, therefore, I do not need to control the heat.
}
10. Provide directions for someone else to run your simulations to reproduce the experiments you got, and describe the results you obtained:
{Make two simulation boxes both with a height of 500 and a width of 400. Apply an outward magnetic field on both simulation boxes with a magnitude of .2 Teslas. Put one ion in each of the simulators. Make each ion be the #1 or Nt atoms with a charge of -1, an x position of 15, a y position of 45, a .7 angstrom interaction (or sigma), a zero x velocity, a y velocity of 1000 m/s, a zero for all other values. Make one ion have a mass of 80 g/mol and the other have a mass of 40 g/mol. Run each simulation separately, letting it go a little after one full circle. Return the ion back to the starting position after the full circle was completed and divide the time value by two. Go to the resulting time value and read the x and y values of that position. Take the x and y values from this and subtract the x and y compontents from the initial position from them to get a vector sum for the change in position. Combine the x and y components. This will be the diameter of the circle made by the ion. Divide this number by two to get the radius.
}
11. State the answer to your question and intepret the results in terms of relevant fundamental concepts (for example, Conservation of momentum, conservation of energy, conservation of charge, Coulomb's Law, Entropy, etc.). Any surprises?
{
}
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