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Mass Spectrometry Difficult Question

An ionised sample contained the ions 23Na which had a time of flight of 1.134 x 10 -5 s and an unknown element X whose ions had a time of flight of 1.689 x 10 -5 s. Find the Ar of the unknown element.I have just started AS-Level Chemistry and I am not really sure how to approach this question.

Reply 1

charco

Study Forum Helper

Original post by RK1506

All particles are accelerated wth the same energy.

Hence, if you use the sodium ionic mass you can work out the energy from 1/2mv² in terms of distance travelled (velocity = distance/time)
You know that the distance travelled to the target sensor is the same, so you can use the distance travelled to find the velocity of the unknown element and hence it's mass.

Reply 2

Crunch_chemistry

Type 'AQA time of flight' into Google, AQA produced a set of notes, practice questions and answers on this material since text books cover it so badly. There are also a couple of good videos on YouTube covering these sorts of calculations.