A mass spectrometer is set up to measure the mass to charge ration (m/z) of chem

Question

A mass spectrometer is set up to measure the mass to charge ration (m/z) of chemicals by ionizing a molecule by stripping it of one of its electrons and sending it through an area with a constant magnetic field of 0.25T. After the ions have travelled a radial 180 degrees with a speed of 1.6 e^6 m/s, they are detected by a counting the number of ions that hit a movable detector.

If we use this mass spectrometer to analyze the carbon monoxide (12C 16O), we find that most of the molecules peak at m/z 28. However, about 1% of the molecules are detected at m/z 29.

a.     A.) How far in cm did the detector move between these two peaks?

b.     B.) If a 0.5 ug sample is used and it takes 1 hour to run the entire sample through the machine, what is the effective current produced by the ions?

c.     C.)  If the heavy isotopes of carbon monoxide were directed into a cup, how much energy would the cup gain in the form of heat?

A mass spectrometer is set up to measure the mass to charge ration (m/z) of chemicals by ionizing a molecule by stripping it of one of its electrons and sending it through an area with a constant magnetic field of 0.25T. After the ions have travelled a radial 180 degrees with a speed of 1.6 e^6 m/s, they are detected by a counting the number of ions that hit a movable detector. If we use this mass spectrometer to analyze the carbon monoxide (12C 16O), we find that most of the molecules peak at m/z 28. However, about 1% of the molecules are detected at m/z 29. How far in cm did the detector move between these two peaks? If a 0.5 ug sample is used and it takes 1 hour to run the entire sample through the machine, what is the effective current produced by the ions? If the heavy isotopes of carbon monoxide were directed into a cup, how much energy would the cup gain in the form of heat?

Explanation / Answer

the atomic number will remain same... so change will remain same... but mass will change..

case 1 ...

m/z = 28..

so.. m = 28 z

q = charge = e , where e = charge of 1 proton

v = 1.6 * 10^6 m/sec

mass = 28 z * mp , where mp = mass of proton = 1.67 * 10^-27 kg

so m = 28z * 1.67 * 10^-27 = 4.676 * 10^-26 * z kg

now for 180 degrees...

mv^2 / radius = q*B*v

so.. radius = mv / (qB) = (4.676 * 10^-26 * z* 1.6 * 10^6 ) / ( 1.6 * 10^-19   * 0.25 )

z = 12 + 16 = 28

so radius ( for m/z = 28 ) = 52.3712 metres

radius ( for m/z = 29 ) = 54.2416 metres

so movement = 2 * ( 54.2416 - 52.3712) * 100 = 374.08 cm

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