This is a question about time of flight (TOF) mass spectrometry.
Give the equation, including state symbols, for the formation of Ne+\text{Ne}^+Ne+ ions from Ne\text{Ne}Ne atoms by electron impact.
A sample of neon is analysed by TOF mass spectrometry. The sample is ionised using electron impact. The ions are accelerated to have a kinetic energy (KEKEKE) of 3.36×10−18 J3.36 \times 10^{-18}\text{ J}3.36×10−18 J. An ion takes 1.18×10−4 s1.18 \times 10^{-4}\text{ s}1.18×10−4 s to travel along a 160.0 cm160.0\text{ cm}160.0 cm flight tube.
KE=12mv2KE = \frac{1}{2}mv^2KE=21mv2
where m=mass (kg)m = \text{mass (kg)}m=mass (kg) and v=speed (m s−1)v = \text{speed (m s}^{-1}\text{)}v=speed (m s−1). Use the information given to deduce the mass number of this ion. The Avogadro constant, L=6.022×1023 mol−1L = 6.022 \times 10^{23}\text{ mol}^{-1}L=6.022×1023 mol−1.
Explain how the ions are detected in the TOF mass spectrometer. State how the relative abundance of the ions is determined.
A sample of neon contains three isotopes, 20Ne^{20}\text{Ne}20Ne, 21Ne^{21}\text{Ne}21Ne and 22Ne^{22}\text{Ne}22Ne. 90.5%90.5\%90.5% of the sample is 20Ne^{20}\text{Ne}20Ne. The other isotopes are in a 1:181:181:18 ratio of 21Ne:22Ne^{21}\text{Ne} : ^{22}\text{Ne}21Ne:22Ne. Calculate the percentage abundance of 22Ne^{22}\text{Ne}22Ne in this sample. Use your answer to deduce the relative atomic mass (ArA_rAr) of the sample. Give your answer to 1 decimal place.
Electrospray ionisation is used instead of electron impact for the ionisation of a large polypeptide in a mass spectrometry experiment. Suggest why.