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WorksheetsAnalytical Techniques
Total questions: 35
Worksheet time: 1hrs 2mins
Which technique would be most appropriate to indicate the three-dimensional structure of a molecule?
X-ray crystallography
mass spectroscopy
chromatography
infrared spectroscopy
Which of the following statements about the electromagnetic spectrum is false?
Electromagnetic waves with a longer wavelength have a lower frequency.
All aspects of the spectrum travel at the same speed.
X-rays have a higher frequency than visible light.
All aspects of the spectrum have the same energy.
Which of the following does not affect the amount of deflection during mass spectroscopy?
mass of the particle
strength of the magnetic field
charge of the particle
atoms that contribute to the mass of the particle
Which of the following is not detected during mass spectroscopy?
positive ions
a cation with a charge of +
a radical
a cation with a charge of +1
In X-ray crystallography the crystals are usually produced by:
rapidly cooling supersaturated solutions.
slowly cooling unsaturated solutions.
rapidly cooling unsaturated solutions.
slowly cooling supersaturated solutions.
X-rays may be produced when electrons move to an energy level that is:
slightly further away from the nucleus.
significantly further away from the nucleus.
slightly closer to the nucleus.
significantly closer to the nucleus.
X-ray crystallography is based on the scattering of:
light by electrons.
X-rays by protons.
X-rays by electrons.
light by protons.
During infrared spectroscopy the frequencies absorbed depend on:
whether the bond is single, double or triple.
the atom’s size.
the bond length.
all of the above
What characteristic of the light absorbed is compared between known and unknown samples in UV-visible spectroscopy?
frequency
energy
wavelength
colour
Carbon dating of fossils is based on the ratio of carbon-12 to carbon-14. The technique used is:
X-ray crystallography.
mass spectroscopy.
chromatography
infrared spectroscopy.
The correct order for the steps in mass spectroscopy is:
detection, acceleration, ionisation, deflection.
ionisation, deflection, acceleration, detection.
ionisation, acceleration, deflection, detection.
acceleration, ionisation, deflection, detection.
A sample is analysed using mass spectroscopy and the following results are obtained. The base peak for this sample has an m/z value of:
98
83
55
29
An unknown element produces the following mass spectrum. Based on this result the average relative atomic mass of the element
11
10.8
10.5
13
In X-ray crystallography the crystals are rotated so that the:
angle of incidence of the X-rays changes.
X-rays are presented to all surfaces of the crystal.
angle of reflection of the X-rays changes.
crystal does not melt.
The fingerprint region in an infrared spectrum is the most useful region because:
it contains all the troughs
it is the same for all molecules with the same functional group
each molecule will produce a different pattern in this region due to complex bending.
it contains all the peaks for the molecule.
A sample of a hydrocarbon is analysed using a mass spectrometer and the following mass spectrum is obtained. Given that the compound is known to be an alkane, it is most likely to be:
propane.
butane.
pentane.
Methyl propane
A sample of ethanol is analysed using mass spectroscopy. From the data in the mass spectrum what is the fragment producing the base peak?
CH3CH2OH+
CH3CH2+
CH2OH+
OH+
Boron (relative atomic mass (RAM) = 10.81 amu) consists of two isotopes: 10B (RAM = 10.013 amu) and 11B (RAM = 11.009 amu). What is the percentage abundance of 10B?
50.0%
20.0%
80.0%
15.0%
In the electromagnetic spectrum, when compared with violet light, red light has:
less energy, longer wavelengths and lower frequency
more energy, longer wavelengths and higher frequency.
more energy, shorter wavelengths and higher frequency.
less energy, longer wavelengths and higher frequency.
In mass spectrometry:
only anions are detected.
smaller cations are deflected more by the magnetic field.
anions, cations and neutral atoms produce individual peak
cations with greater masses produce higher peaks.
Which relative molar mass can not be produced by the fragmentation of propene?
30
27
15
14
The correct order for the steps in X-ray crystallography is:
atomic model, obtain a crystal, expose to X-rays, record diffraction pattern.
obtain a crystal, atomic model, expose to X-rays, record diffraction pattern.
expose to X-rays, record diffraction pattern, atomic model, obtain a crystal.
obtain a crystal, expose to X-rays, record diffraction pattern, atomic model.
The diffraction pattern produced due to scattering of X-rays:
allows an electron density map to be produced.
is the same for all angles of incidence.
is the same as when visible light is passed through a crystal.
cannot determine bond length or angles.
An infrared spectrum can be used to:
identify the presence of certain functional groups.
identify the absence of certain functional groups.
identify an unknown sample by comparing it to a known sample.
do all of the above.
What wavenumbers correspond to the fingerprint region of an infrared spectra?
<1400 cm–1
1400–2000 cm–1
2000–3000 cm–1
>4000 cm–1
What analysis technique is most suitable to identify the isotopes of an element?
chromatography
X-ray diffraction
mass spectroscopy
infrared spectroscopy
The charge of most ions produced in the ionisation step of mass spectroscopy is:
-1
0
+1
+2
A molecule with an unpaired electron is known as:
an ion.
a radical.
a cation.
a radion.
Consider the following pairs of compounds. Analyse which absorption band in the infra-red spectrum could be used to distinguish between them.
Explain how electrophoresis is a process used to analyse proteins
Explain why it can be difficult to distinguish between cobalt and nickel ions in a compound by X-ray crystallography, but easy to distinguish between cobalt and rhodium ions.
Describe how size exclusion chromatography
works to separate proteins.
Explain what information can be determined from particular parts of the spectrum.
Compare and contrast the techniques of electrophoresis and chromatography.
Infrared and mass spectra can be used to determine the structures of molecules. Describe how these techniques differ in this task and justify if just one of these is sufficient
