The effect of temperature on the absorbance of ... - Woodbridge High

<strong>The</strong> <strong>effect</strong> <strong>of</strong> <strong>temperature</strong> on the absorbance <strong>of</strong>
transmitted light <strong>of</strong> different frequencies <strong>of</strong> light for
different concentrations <strong>of</strong> a bleach and grape juice
solution
John Barns
Grade 11, Per. 3
2/2/09

Purpose/ Hypothesis
Purpose
<strong>The</strong> purpose <strong>of</strong> this experiment was to determine if
<strong>temperature</strong> would affect the absorbance <strong>of</strong> transmitted <strong>of</strong>
light for different concentrations <strong>of</strong> a bleach- grape juice
solution.
Hypothesis
It is believed that the highest <strong>temperature</strong> on the lowest
concentration <strong>of</strong> the solution will decrease the amount <strong>of</strong>
absorbed light for the solution the greatest and that the
lowest <strong>temperature</strong> on the highest concentration will
increase the amount <strong>of</strong> absorbed the greatest amount.

Background Research
<strong>The</strong> process <strong>of</strong> bleaching can occur in one <strong>of</strong> two
ways.
1. Either the bleach can oxidize the substance, breaking
the chemical bonds that make up the molecules in a
substance that generate the color.
2. it can change the double bonds <strong>of</strong> a molecule that
produces a color into single bonds, changing its
ability to absorb light.
<strong>The</strong> molecule in most solutions that produces the
visible color is called a chromophore.

Background Research
(cont.)
<strong>The</strong> addition <strong>of</strong> bleach into a solution or its
application to a surface such as clothing, which
contains dyes, will change the ability <strong>of</strong> the dye to
absorb any transmitted light <strong>of</strong> similar wavelengths.
When the ability <strong>of</strong> a dye or chromophore to
transmit or absorb a certain color is changed, the
result is an overall fading <strong>of</strong> the originally dominant
color.
Bleach is used because it breaks the chromophore
bonds and shifts the color to white, which is a basic
palate for other colors.

Background
Research (cont.)
Portable Colorimeter
Beer’s Law states that the
original absorbance <strong>of</strong>
light by a solution is
directly proportional to the
concentration <strong>of</strong> the liquid.
Beer’s Law is represented
by the equation;
I=I0x10^(-kcl)
To measure the
absorbance <strong>of</strong> light, a
colorimeter is needed.
A colorimeter uses a
photometer to measure
the amount <strong>of</strong> light that
passes through a solution
and how much <strong>of</strong> that light
is absorbed by the solution
itself.

Methods/ Materials
<strong>The</strong> manipulated variable was the <strong>temperature</strong> <strong>of</strong> the bleach
solution.
<strong>The</strong> responding variable was the percent <strong>of</strong> transmitted light
that was absorbed by the solution.
Controls:
the concentration <strong>of</strong> the bleach solution
the frequency <strong>of</strong> light being used to record the absorbance <strong>of</strong>
transmitted light
the absorbance <strong>of</strong> the 100% grape juice and 100% bleach
the type <strong>of</strong> bleach used
the grape juice used
the amount <strong>of</strong> solution in each vial used for data collection

Methods (cont.)
A colorimeter was used to quantify the amount <strong>of</strong>
light that was absorbed by each solution
To determine what the affect <strong>of</strong> <strong>temperature</strong> was on
different concentrations, 5 different concentrations
<strong>of</strong> bleach were mixed with grape juice, a common
staining agent
<strong>The</strong> amount <strong>of</strong> absorbed light for each <strong>of</strong> these
samples was recorded and then trials were
conducted that involved varying the <strong>temperature</strong>s <strong>of</strong>
each sample

Methods (cont.)
In order to change the <strong>temperature</strong> in a consistent
ratio for each sample, all 5 samples were immersed in
both a hot water bath and a cold water bath, with the
average <strong>temperature</strong> <strong>of</strong> the water being measured
accurately by an electronic thermometer which
tested the <strong>temperature</strong> every 4 seconds
<strong>The</strong> results were recorded for each percent solution
and at each <strong>temperature</strong>

Results
•<strong>The</strong> overall trend in data
shows that there is an inverse
relationship between the
<strong>temperature</strong> <strong>of</strong> a solution and
the amount <strong>of</strong> light that it
absorbs
•Figure 1 is a sample <strong>of</strong> data,
demonstrating the overall
trend <strong>of</strong> the amount <strong>of</strong>
absorbed light
Concentration-
25%
Temperature
%
Transm
ittance
%
Absorbance
2.64 14.90 -0.76
red 18.34 16.50 -0.80
32.53 19.10 -0.95
2.64 6.80 0.01
Green 18.43 6.60 0.11
32.53 8.30 -0.10
2.64 0.60 0.60
Blue 18.34 0.60 0.60
32.53 0.70 0.70
2.64 11.10 11.10
Orange 18.34 10.90 10.90
Figure 1

Discussion/ Analysis
<strong>The</strong> original hypothesis is supported by the data.
<strong>The</strong> amount <strong>of</strong> red light that was absorbed by the
grape juice was most affected by the change in
<strong>temperature</strong>
If the experiment had been tried with a different
colored solution with the bleach the affect that
<strong>temperature</strong> would have had on the absorbance <strong>of</strong>
other wavelengths may have been altered.

Discussion (cont.)
<strong>The</strong> overall <strong>effect</strong> <strong>of</strong> <strong>temperature</strong> on absorbance <strong>of</strong>
transmittance <strong>of</strong> light is very small however, as there is
not a large visible difference in the visible color <strong>of</strong> the
solution.
<strong>The</strong> experiment may have been much more controlled if a
single wavelength <strong>of</strong> light had been focused on or if there
had been multiple trials conducted for each set <strong>of</strong> data
<strong>The</strong> data seems to show that bleach becomes more
<strong>effect</strong>ive as the <strong>temperature</strong> <strong>of</strong> the solution is raised, as
this allows the overall absorbance <strong>of</strong> light to be decreased
by the largest amount for a staining agent.

Conclusion
<strong>The</strong> original purpose <strong>of</strong> this experiment was to determine
if bleach would become more <strong>effect</strong>ive as a stain remover
as the <strong>temperature</strong> <strong>of</strong> a solution was increased
<strong>The</strong> data collected supports that the warmer a solution <strong>of</strong>
bleach, the more <strong>effect</strong>ive it is in accomplishing its goal <strong>of</strong>
decreasing the overall absorbance <strong>of</strong> the original
wavelengths <strong>of</strong> light for a solution.
By using a colorimeter, the results can be viewed as being
appropriately accurate

Future Research/
Applications
In the future it may be more helpful to use a wider
variety <strong>of</strong> solutions and wavelengths <strong>of</strong> light
<strong>The</strong> <strong>temperature</strong> <strong>of</strong> the solutions may be more
closely controlled in the future
This can be applied when dealing with cleaning
clothing or other stained materials with bleach

Literature Sources
D.M. Coons. “Bleach: Facts, Fantasy, and Fundamentals”
Jan. 1978. J.AM. Oil Chemist’s SOC. (Vol. 55) July 2007
http://www.springerlink.com/content/y181204t1t643964/
Chemistry Teaching at the University <strong>of</strong> Cambridge 10
Sept. 2008 http://wwwteach.ch.cam.ac.uk/teach/IA/KCR_full.pdf
Caprette, David R. “Principles <strong>of</strong> Spectrophotometry.
“Experimental Biosciences. 16 Sept. 96. Rice University. 25
Sept. 2008
http://www.ruf.rice.edu/~bioslabs/methods/protein/spectr
ophotometer.html

Acknowledgments
I would like to thank my dad for providing the
equipment for measuring the <strong>temperature</strong> precisely
and for providing a good work space
I would also like to thank my teacher Mr. Antrim for
providing the colorimeter and the overall idea for the
project