Briana Byrne
5th hr
Spectrum Lab
Intro:
Everyday, doctors are treating new and different things. Behind every disease or problem
a patient may come along with is the origin of past symptoms a doctor has observed. Doctors
make decisions on what to do based on what they have learned and what they have
experienced/done in the past. Based on what was observed during this lab and what was recorded
from the spectroscope, the unknowns should be easy to figure out. Wavelengths are recorded by
the calibrated scale on the spectroscope designed to show the wavelength of each color of the
spectrum. A line spectrum is how the wavelengths are represented in a spectroscope. This means
that the color spectrum will have distinct lines at a specific wavelength for that color. To
determine the percent error, the equation (true-experimental)/true is used. Comparing the
calculated wavelength and the actual length is how this will be found, determining whether the
spectroscopes were calibrated correctly and if the lab was accurate. If the wavelengths of
emission lines are determined then the unknowns may be determined.
Materials & Methods:
Each element was poured into a Petri dish and lit. Then, the flame was observed through
a spectroscope and each color was recorded with the number at which the light appeared.
Results:
Table 1: Spectrum tube
Hydrogen
Observed
color
purple
blue
teal
Lime
green
Yellow
Orange
Red
Observed
wavelength
440 nm
460 nm
500 nm
550 nm
590 nm
620 nm
650 nm
True
wavelength
%
error
Light: 410
nm
Dark: 435
nm
Light:
7%
Dark:
1%
660 nm
1.5%
Briana Byrne
5th hr
Lithium
Strontium
Potassium
Color
Purple
Dark green
Yellow green
Lime green
Yellow
Orange
Red
Observed
TRUE
%error
450 nm
Not listed
500 nm
550 nm
530 nm
600 nm
640 nm
700 nm
Color
Observed
Purple
TRUE
%error
450 nm
405 nm
11%
Blue
510 nm
445 nm
14%
Blue green
570 nm
500 nm
14%
Orange
610 nm
585 nm
4%
Red
660 nm
670 nm
1%
Color
Observed
TRUE
%error
Purple
440 nm
405 nm
8%
teal
500 nm
480 nm
4%
lime green
570 nm
535 nm
6.50%
orange
620 nm
610 nm
1.60%
red
640 nm
695 nm
7.90%
Color
Observed
TRUE
%error
Briana Byrne
5th hr
Sodium
Calcium
Barium
purple
450 nm
440 nm
2.30%
teal
500 nm
495 nm
1%
green
580 nm
520 nm
11.50%
orange
620 nm
590 nm
5%
red
640 nm
Color
Observed
TRUE
%error
dark purple
400 nm
390 nm
1%
light purple
440 nm
420 nm
4.70%
teal
500 nm
500 nm
0%
lime green
570 nm
530 nm
7.50%
orange
610 nm
620 nm
1.60%
red
660 nm
645 nm
2.30%
Color
Observed
TRUE
%error
purple
420 nm
415 nm
1.20%
teal
460 nm
495 nm
7%
lime green
580 nm
555 nm
4.50%
orange
630 nm
615 nm
2.40%
red
670 nm
650 nm
3%
Color
Observed
TRUE
%error
Briana Byrne
5th hr
Unknown1 purple
teal
520 nm
green
560 nm
lime green
590 nm
orange
620 nm
red
710 nm
Color
Observed
Unknown2 purple
Light
450 nm
450 nm
unknown
TRUE
%error
unknown
teal
520 nm
green
560 nm
orange
620 nm
red
710 nm
Color
Observed
Purple
430 nm
400 nm
7.5%
blue
450 nm
450 nm
0%
teal
500 nm
490 nm
2%
green
560 nm
520 nm
7.7%
yellow
610 nm
590 nm
3.4%
orange
640 nm
620 nm
3.2%
TRUE
%error
Briana Byrne
5th hr
Ethanol
Color
Observed
Purple
450 nm
teal
500 nm
green
560 nm
orange
640 nm
TRUE
%error
Not listed
Table 2: Flame spectrum
wavelength related to energy transitions
Level 6 to 2 : 2.19 * 1023
level 5 to 2 : 2.07 * 1023
level 4 to 2 : 1.85 * 1023
level 3 to 2 : 1.37 * 1023
Sample calculation of a wavelength:
1/lambda = RH/hc (1/nf2 – 1/ni2)
Level 6 to 2: 1/lambda = RH/hc (1/22- 1/62)
= 2.19 * 1023
Conclusion:
The lab results made sense and were very close to the true wavelength. All spectroscopes
were calibrated the same. The amount of light in the room affected the spectrum because some of
the light was included in the calculations, therefore throwing the numbers off a little. But, in
order to see the scale it was necessary to have light in the background while observing. I would
need line spectrum measurements to determine for sure the unknown in order to compare exact
numbers. But, the unknowns assumed to be in the first were Barium and potassium; in the second
unknown, potassium and strontium. In the first unknown, barium matches or is close to most of
the colors calibrated in the lab and potassium is almost exactly the same numbers of wavelength
as the unknown. The second unknown was determined to have potassium because the
wavelengths match very close, and strontium is also very close in the number wavelengths for
each color in the spectrum. There was little percent error, but, where the error occurred was from
the background light or the angle the flame was being observed. Mechanics need to know what
Briana Byrne
5th hr
past vehicles have had wrong with them and observe what could be going wrong in order to find
the problem. They have a mind trained to listen for certain things from experience in order to be
successful. This lab uses past wavelengths to compare to the unknowns in order to figure them
out.