Why can't we see N2 and H2 in color?

  • Context: High School 
  • Thread starter Thread starter Muthumanimaran
  • Start date Start date
  • Tags Tags
    Color
Click For Summary
SUMMARY

Nitrogen (N2) and hydrogen (H2) gases are colorless due to their electronic states being far apart in energy, which prevents them from absorbing visible light. Both gases primarily absorb in the vacuum ultraviolet region of the spectrum. Additionally, isolated N2 and H2 molecules do not display rotational or vibrational spectra. However, emission bands can be observed in the visible region when an electric discharge is passed through these gases at low pressure.

PREREQUISITES
  • Understanding of electronic states in molecular physics
  • Knowledge of vacuum ultraviolet absorption
  • Familiarity with gas discharge phenomena
  • Basic principles of spectroscopy
NEXT STEPS
  • Research the principles of electronic transitions in molecular gases
  • Explore vacuum ultraviolet spectroscopy techniques
  • Study the effects of electric discharge on gas emissions
  • Learn about rotational and vibrational spectra in diatomic molecules
USEFUL FOR

Students and professionals in chemistry, physicists studying molecular behavior, and anyone interested in the optical properties of gases.

Muthumanimaran
Messages
79
Reaction score
2
why N2, H2 gas are colourless when visible light scatters it? why can't i see N2 and H2 coloured
 
Physics news on Phys.org
Muthumanimaran said:
why N2, H2 gas are colourless when visible light scatters it? why can't i see N2 and H2 coloured

The simple answer is that the electronic states of nitrogen and hydrogen are very far apart in energy. Both of these gases absorb in the vacuum ultraviolet region of the spectrum. The isolated gas molecules do not exhibit rotational or vibrational spectra, either.

There are emission bands between excited states of N2 and H2 that are in the visible region. You can see many of these if you pass an electric discharge through the gases at low pressure.
 
  • Like
Likes   Reactions: Pierce610, Muthumanimaran and Greg Bernhardt

Similar threads

High School Why are things the color they are?
  • · Replies 3 ·
Replies
3
Views
3K
High School Why Does Ice Appear White?
  • · Replies 35 ·
2
Replies
35
Views
6K
High School Do Electrons Get Excited and De-Excited Equally in Colored Compounds?
  • · Replies 2 ·
Replies
2
Views
2K
Predicting Remaining Pressure in Compressed Gas Cylinder
  • · Replies 3 ·
Replies
3
Views
3K
Chemistry Absorption of light by molecules and the reasons for this
  • · Replies 19 ·
Replies
19
Views
11K
Undergrad Spectrometer Shows More Blue light on cloudy Day....why?
  • · Replies 4 ·
Replies
4
Views
2K
Determine energy levels of a electron in a hydrogen atom
  • · Replies 8 ·
Replies
8
Views
2K
Undergrad Why does the effect linger with Glow in the dark?
  • · Replies 16 ·
Replies
16
Views
6K
High School Scattering of light inside a room
  • · Replies 22 ·
Replies
22
Views
3K
High School Why can't we just recycle polluted air?
  • · Replies 17 ·
Replies
17
Views
2K