Chlorophylls reaction to the visible spectrum Introduction/aim: To investigate the effect of chlorophyll on visible light in aspectrum. Question/hypothesis If the solution of chlorophyll is put in a beam of light then thegreen will disappear from the spectrum.Backgroundtheory: To be able to understand the concept ofchlorophylls reaction to the visible light, we have to learn aboutphotosynthesis and light. Starting we have Photosynthesiswhich is a process plants use to turn light energy into sugar (glucose) to beable to gain energy (nutrition) for themselves.
The plants (autotrophic such asalgae) contain pigments found in the chloroplast of the cell plants. In thechloroplast there is a pigment called chlorophyll (plants have two types,chlorophyll a and b). The chlorophyll only absorbs the red and blue light(light waves) which becomes a reflection of green and therefore gives theplants a green reflection. The light that the plants absorb travels in waves, aform of electromagnetic radiation. The focus for now is to learn about thevisible spectrum, which is “the only part of the electromagnetic spectrum thatcan be seen by the human eye” (Khan Academy, 2014).
When the sun shines onplants, we see the light as white but in fact, it consists of different colors,which we can see through a prism. When the white light shines on a prism, thewavelength of light bends into different angles that spread out, and thereforturns into the colors of the rainbow, all colors visible by the human eye. (KhanAcademy, 2014) Materials:- Leaves- Beaker (small)- Beaker (big)- Mortar- Acetone- Sand- Heat pan/hot plate- Visible light beam- Prism- Scissor- Tweezer- Filter paper- Plastic rap- Funnel- Water- Cuvette Method:1.
Start with boiling water on aheat pan, add your leave, and let it be in the water for 1 minute.2. Take out the leave from thewater and cut the leave into small pieces.
3. Put the small leave pieces intothe mortar and start molting the leaf with a bit of sand.4. Add some acetone to the sandleaf mixture and keep on molting until you are left with a dark green mixture.5.
Now that you have the darkgreen mixture, filter the solution using a filter paper and a funnel and pourthe filtered solution into a beaker.6. Add the plastic wrap on to thebeaker filled with the filtered green solution7. Turn on the visible light andshine it on the whiteboard.
8. Use the prism to break thevisible light into the different parts of light that white light has.9. Hold the chlorophyll betweenthe light and the prism.10.
Observe the results and writethem down. Results:The colors in the visible turned green dueto the chlorophyll solutions reflection. This happened when the solution wasplaced in front of the prism and visible light was shined onto the prism(picture shown above) Conclusion:In my hypothesis, I wrote that I think thatif the solution of chlorophyll is put in a beam of light then the green willdisappear from the spectrum, which was wrong. The correct hypothesis would bethat if the solution of chlorophyll is put in a beam of light then the greenwill out shine all the colors from the spectrum turning them all into the samecolor as the chlorophyll solution, which is green. This means that myhypothesis was incorrect, in other words it was refuted since the green colordid not disappear, instead all other colors turned green. Discussion:When looking back at the backgroundtheory, we learn that plant chlorophyll consists of both chlorophyll a and bwhich absorb the red and blue light (light waves). The green light waves arenot absorbed but reflected instead which gives plants their green appearance.This makes it obvious that the color of the solution, which was green, will bethe reflection showed on the whiteboard when held in front of a prism becausethe red and blue are absorbed and not shown back.
We use a prism to be able tosee all the colors individually but since the leaf absorbs the red and bluecolors, the only reflection will be the green wavelengths. So even though theprism is separating for you, only the green is really getting reflected andshown. The color that the human eye sees in plants is mostly due to whichcolors are absorbed by the plant and which ones are reflected. Sourcesof errors:Some errors that could occur whilepreceding this experiment could be that you didn’t mold the leaf enoughresulting in a light green liquid instead of a dark strong color of green. Thiswould lead to a failure when putting the liquid in front of the prism since thecolor would be to weak to out shine the rest of the colors. This is somethingthat happened to a group resulting in not all visible colors becoming green,only some that isn’t correct.
Therefore, you have to be sure to mold the leafmixture until you have a dark green liquid. Another error could be the measurement ofeach ingredient. On the description, it said that you should add a pinch ofsalt and a small amount of acetone which if you use to less or too much ofcould ruin the result. If you use too much sand the mixture could become toothick which could make the solution grumbly and give you inaccurate resultswhen the light shining onto the prism hits the solution. If you have too muchacetone, the liquid can become to liquidly and give a light green color eventhough you molded the leaf as much as possible which also would give you aninaccurate result.
Therefore, you have to be careful when adding ingredients toyour mixture. A way to improve the results in this experiment accordingcould be to try the same experiment with a prism but with different plants thatconsist of other colors such as a pink flower or a yellow dead leaf. In thatway, you would change the variable since these plants consist of other pigmentssuch as yellow and red and then see how their reflection would be shown infront of the prism. Then you could compare and see if they also outshine theother colors like the green did or if the green color is a stronger one and howdifferent pigments are stronger than others are. Referencelist: – https://www.khanacademy.org/science/biology/photosynthesis-in-plants/the-light-dependent-reactions-of-photosynthesis/a/light-and-photosynthetic-pigmentsKhan Academy, 2014.Accessed 2017-11-10- Own knowledge from Ms Galleys lessons