An accelerated iron Ion moving through a mass spectrometer's field

In summary, a sample of two different iron ions, Fe2+ and Fe3+, are accelerated by the same potential and then sent through the uniform magnetic field of a mass spectrometer. After being accelerated, the Fe3+ ion moves faster due to its stronger charge and smaller mass. In terms of path radius, equating the centripetal force to the force of a moving charge in a magnetic field shows that the Fe2+ ion will follow the path with the largest radius.
  • #1
slybuster
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Homework Statement



A sample of two different iron ions, Fe2+ and Fe3+, are accelerated by the same potential and then sent through the uniform magnetic field of a mass spectrometer.

a) Which ion moves faster after being accelerated?
b) Which ion follows the path with the largest radius?

Homework Equations



a)
Ek = 1/2mv^2
v= sqrt|(2qV)/m|
??v= (qBr)/m??

b)
Fc= (mv^2)/r
r = sqrt|(m2V)/(qB)|



The Attempt at a Solution



a) Stated that Fe3+ had a stronger charge and a smaller (though negligibly) mass. Related this to the Ek and v= sqrt|(2qV)/m| equations in order to show that it would have a faster velocity. I think I'm alright here...

b) This is where I have trouble. My gut tells me that the Fe2+ should have the larger radius (when I picture the charge in my head it has a lower Ek and gets deflected more). However, relating the equations is confusing me as I keep getting tripped up by thinking that the larger charge of the Fe3+ ion will cause it to experience more force and thus a wider radius pushing it. Maybe I should be picturing it enter the field from over top? (i.e. (x) and not from the side -->). Also, I want to try and set up r(Fe+3)/r(Fe+2) = ?/? but can't figure out which equation to use on the right side...

Help is very much appreciated.
 
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  • #2
Equate centripetal force to the force of a moving charge in a magnetic field. What do you get?
 

1. How does a mass spectrometer work?

A mass spectrometer is a scientific instrument used to measure the mass of particles present in a sample. It works by ionizing the particles and then separating them based on their mass-to-charge ratio. This is done by accelerating the particles through an electric field and then bending their path using a magnetic field. The particles are then detected and their mass-to-charge ratio is measured, allowing for identification and quantification of the particles present in the sample.

2. What is an iron ion and why is it used in mass spectrometry?

An iron ion is a positively charged particle that consists of one iron atom. It is often used in mass spectrometry because it has a relatively high mass-to-charge ratio, making it easier to detect and measure accurately. Additionally, iron is a commonly found element in many samples, making it a useful ion to use for identification and quantification.

3. How does the acceleration of iron ions affect their behavior in a mass spectrometer?

When an iron ion is accelerated through an electric field in a mass spectrometer, it gains kinetic energy. This energy allows the ion to travel faster and reach the detector more quickly. It also causes the ion to experience a greater force when passing through the magnetic field, which results in a larger deflection of its path. This allows for better separation and identification of the iron ion among other particles in the sample.

4. What factors can affect the speed and accuracy of an iron ion moving through a mass spectrometer?

The speed and accuracy of an iron ion in a mass spectrometer can be affected by a number of factors, including the strength of the electric and magnetic fields, the initial velocity and charge of the ion, and any interferences or contaminants in the sample. Other factors such as temperature and pressure can also affect the behavior of the ion.

5. How is data collected and analyzed in a mass spectrometer?

As the iron ion and other particles are detected by the mass spectrometer, their mass-to-charge ratios are recorded. This data is then plotted on a graph called a mass spectrum, with the mass-to-charge ratio on the x-axis and the abundance or intensity of the particles on the y-axis. From this data, scientists can identify the different particles present in the sample and determine their relative abundance or concentration.

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