Chem 1a Flashcards
Other than relative mass of each isotope, what else would need to be known for the Ar of Cr to be calculated?
Need relative abundance of each element
Why must the sample be ionised in a TofF spectrometer?
So it can be accelerated and can be pick up an electron at the detector.
In TofF, what needs to be adjusted to allow distinction between samples of different isotopes?
Magnetic field
Explain how the adjustment of magnetic field in TofF enables isotopes of the sample to be separated?
Deflection depends on mass or m/z
Why does Neon have a high first IE than Na?
Electron is being removed from a shell of lower energy, e– is removed from 2p rather than from 3s, less shielding
1st ionisation energy
Enthalpy change when an electron is removed from 1 mole of gaseous atoms.
Why is a mass spectrometer incapable of distinguishing between the ions 14N+ and 14N(2+)2?
same M/Z
Why would F- be unlikely to reach the detector?
Not accelerated
Why does He has a higher first ionisation energy than Li?
He’s e- in 1s, so closer to nucleus and no shielding.
Explain why beryllium has a higher first ionisation energy than boron
Be’s outer electron in 2s, which is lower in energy than 2p
Explain why the first ionisation energy of krypton is greater than the first ionisation energy of bromine.
Greater nuclear charge, and similar shielding throughout atom.
Explain why the second ionisation energy of beryllium is greater than the first ionisation energy.
E- being removed from positive ion, so greater attraction present.
Why does water not affect titre value?
Water does not change the number of moles of either reagent
Suggest ways to improve a titration?
- Wash solid from weighing container into the beaker
- Wash rod after use
- Wash beaker after transfer to flask
- Wash filter funnel after transfer
- Use teat pipette to make up to the mark on flask
- Ensure bottom of meniscus is on graduation mark
- Mix final solution in flask
How is TOF able to separate isotopes in a sample?
Cations are accelerated to a constant kinetic energy, different m/z have the same kinetic energy and move faster, ions with lower m/z arrive first at the detector.
