22.2. Mass spectrometry
A subsection of Chemistry, 9701, through 22. Analytical techniques
Listing 10 of 98 questions
Gallium is an element in Group13. A sample of gallium is analysed using a mass spectrometer. The mass spectrum produced is shown. % relative abundance mass 69 71 60.11% 39.89% Explain what is meant by the term relative atomic mass. Calculate the relative atomic mass of gallium in this sample. Give your answer to 4 significant figures. Show your working.  relative atomic mass = Complete the table which describes a gaseous atom of gallium. isotope nucleon number total number of electrons in lowest energy level type of orbital which contains the electron in the highest energy level 71Ga  When gallium is heated in excess chlorine, gallium trichloride, GaCl 3, is made. Draw the shape of the gallium trichloride molecule and suggest the Cl –Ga–Cl bond angle. shape of molecule bond angle  Gallium oxide, Ga2O3, and aluminium oxide react in the same way with HCl and with NaOH. Suggest the equation for the reaction between Ga2O3 and HCl . Suggest an equation for the reaction between gallium oxide and NaOH. 
9701_s20_qp_22
THEORY
2020
Paper 2, Variant 2
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The diagram shows the apparatus used to find the relative molecular mass of a volatile liquid. When 0.10 g of a volatile liquid is injected into the syringe, all of the volatile liquid evaporates and the volume increases by 85 cm3. The heater maintains a temperature of 400 K and the experiment is carried out at a pressure of 101 300 Pa. heater thermometer syringe volatile liquid injected here If the vapour of the volatile liquid behaves as an ideal gas, which expression can be used to calculate the relative molecular mass of the liquid?
9701_s24_qp_13
MCQ
2024
Paper 1, Variant 3
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Natural bromine consists of the two isotopes 79Br and 81Br in roughly equal proportions. The mass spectrum of bromine consists of 5 peaks. Suggest the mass numbers for the 5 peaks and the identities of the species responsible for them. Suggest the ratios of the relative abundances of • the three lines with the highest mass numbers, • the two lines with the lowest mass numbers. Esters of 2,3-dibromopropan-1-ol with phosphoric acid are useful flame retardants used in plastics and fibres. 2,3-dibromopropan-1-ol can be made from propenal by the following two-stage process. CH2 CH2OH CH2 Br CHO C H II I propenal Br CH 2,3-dibromopropan-1-oI A Examiner’s Use Draw the structure of the intermediate A in the box opposite. Suggest reagents and conditions for • reaction I, • reaction II. The mass spectrum of 2,3-dibromopropan-1-ol includes the following peaks. mass number relative abundance 0.3 0.6 0.3 At what mass number would you expect the molecular ion to occur? Identify the molecular formula (including isotopic composition where relevant) of these 6 peaks. mass number molecular formula
9701_w08_qp_4
THEORY
2008
Paper 4, Variant 0
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Questions Discovered
98