Spectroscopy and Synthesis Flashcards

1
Q

Describe what an infrared Spectroscopy graph looks like

A

X-axis is wavenumber in cm^-1
Y is transmittance (amount of radiation that passes through)
The waver number increases from right to left

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2
Q

Describe what the different parts of an infrared spectroscopy graph

A
  1. Left hand side above 1500, there are few absorption so it is easy to interpret.
  2. Right hand side is called the fingerprint region- there are lots of absorption so it an be difficult to interpret
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3
Q

Explain the meaning to the term greenhouse effect

A

Warming of the atmosphere due to the trapping of IR by absorption by molecular bonds.

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4
Q

What are the three most important gases in the Earth’s atmosphere

A

CH4, CO2, H2O

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5
Q

Explain on a molecular level how the greenhouse gases trap heat close to the Eart’s surface

A
  1. Heat (IR) is released from the planets surface.
  2. The IR is absorbed by the molecular bonds which vibrate
  3. The IR is then re-released
  4. Some will continue into space but some is reflected back to the surface keeping the surface warmer
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6
Q

Which two factors determine a gas’s contribution to the greenhouse effect

A
  1. The energy absorbed by the bonds

2. The concentration of absorbing molecules in the atmosphere

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7
Q

Why can the term global warming be misleading

A

Because it suggests that everywhere is warming up. However in some locations climate change will result in cooling.

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8
Q

Write 3 consequences of global warming

A
  1. Climate change
  2. Sea levels rising
  3. Increased incidents of extreme weather
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9
Q

Outline some ways in which nations are attempting to reduce excessive greenhouse and its consequences

A
  1. Reduce release of greenhouse gases- reduce car emissions
  2. Increased use of renewable energy sources/low carbon more efficient energy use
  3. More efficient car engines
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10
Q

Write down 3 pieces of information a mass spectrum of an element can tell you

A
  1. Number of isotopes
  2. The relative mass of each isotope
  3. The relative abundance of each isotope
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11
Q

What does m/z value on the x-axis of a mass spectrum

A
  1. Mass to charge ratio
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12
Q

What peaks would you expect to see on a mass spectrum of organic compounds

A
  1. The m+ ion (molecular ion) which represents the molecular mass of the molecule
  2. There might be an m +1 ion which is much smaller than the m+ ion than molecular ion and one more mass than it.
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13
Q

Write balanced equation showing the ionisation of the following molecules to for the molecular ion

A

pentane + e- → [pentane]+ + 2e-

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14
Q

Write equation to show formations of ion with m/z value of 71 from the hexane

A

[hexane] + → [pentane]+ +CH3

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15
Q

What does infrared radiation cause

A

It causes covalent bonds to vibrate more and absorb energy

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