Luke WangOctober 27, 2009Mr. FergusonBiology 9 3B Diffusion Lab ReportQuestion How will the temperature of the water affect the rate of diffusion?Hypothesis If the water temperature is higher, then the rate of diffusion will increase, and vice versa.Variables Independent Variable Water Temperature Dependent Variable Rate of Diffusion Controlled Variables Amount of water The variation of the amount of water put in to the petri dish can also affect the rate of diffusion, so it must stayed the same for all tests. Amount of Potassium Permanganate Adding different amount of potassium permanganate to the water can affect the rate of diffusion, so same amount of potassium permanganate should be added to the water every time.
Materials • Three petri dishes • Potassium Permanganate • Hot, Normal, Cold water • Two Stopwatches • One Thermometer • One CameraProcedure 1. Get a petri dish 2. Pour hot water into the petri disk until full 3. Put a small amount of potassium permanganate 4. Start the stopwatch immediately after putting the potassium permanganate 5. Wait until the dark purple ﬁlls the bottom of the petri dish 6. Stop the stopwatch 7. Record the data 8. Repeat steps 1-7 for normal and cold water
Table Amount of Time It Took for Diffusion To Complete In Three Different Water Temperatures Trial 1 Trial 2 (Seconds) (Seconds)Hot Water 186 121Normal Water 600 377Cold Water 743 646Graph Rate of Diffusion800 743700 600600 646500400 377300 186200100 121 0Hot Water Normal Water Cold Water Trial 1 (Seconds) Trial 2 (Seconds)
AnalysisThe graph shows that when water is hot, the rate of diffusion is much faster evenwhen comparing to normal temperature water. On the ﬁrst trial the diffusion processﬁnished in 186 seconds, but it took 10 minutes in normal water, and 743 seconds incold water. The diffusion process took the longest in cold water, since it got thelowest water temperature which was only about 5 degrees Celsius. The diffusionprocess in hot water was almost 3.3 times faster then diffusion in normaltemperature water. The such big difference can be explained by the great differencein water temperature. The hot water I used for this experiment was about 70.5degrees Celsius, but the normal water was only about 19 degrees Celsius. The timedifference between diffusion in normal water and cold water was still obvious, eventhough the temperature difference was not as great hot water to normal water. It tookcold water about 1.2 times longer for the diffusion process to complete in the ﬁrsttrial, and about 1.7 in the seconds trial.ConclusionAfter doing this lab, I had a better idea on how the temperature can affect the rate ofdiffusion greatly. Also my hypothesis had been proven to be correct, when thetemperature is higher, the rate of diffusion did increase. Although we had discussabout the factors that will change the rate of diffusion, but this lab create a betterimage in my mind how the rate of diffusion changed when the temperature rises.EvaluationAlthough the data I collected during this experiment had shown higher temperaturewill increase the rate of diffusion. However the great different between the ﬁrst trialand the second trial was very strange. The diffusion process took about 10 minutesin normal water in the ﬁrst trial, but it only took about 377 seconds in the second trial.Things that could have cause that problem were how we determined the diffusionprocess is complete. We decided that when the bottom of the petri dish is completelycoated with a purple color, that is when diffusion is complete. When we did the petridish with the hot water, we put the petri dish on a dark surface, so the color of thewater appeared to be darker, and we used that as our reference. However for thenormal water and cold water, we put the petri dish on a white paper to take betterpictures, which caused the water appear to be lighter. Therefore, we couldnʼt get thesame color as the one we got when we put the petri dish on a dark surface. Nexttime I should have a consistent environment for testing, so the result will be keptaccurate.
Luke WangOctober 27, 2009Mr. FergusonBiology 9 3B Journal How Is This Lab Related to the Cell This lab was generally about how temperature affects the rate of diffusion. Since diffusion is very important to cells, so this lab helped us understand how diffusion will occur in a high temperature environment. We used potassium permanganate and water to simulate what will happen in cells. When potassium permanganate was not put in the water, the water had a low concentration of it. After we put potassium permanganate in the water, the potassium permanganate was a high concentration area. By diffusion thepotassium permanganate will spread out in the water so the level of potassium permanganatewould be about the same level. When cells is lack of something, it has a low concentration ofthat thing, by diffusion the area that has this thing will start to move in to the cell, until thelevel of that thing is balanced. When temperature was increased in this lab, the whole processtook less time to complete, since the particles were moving faster in the water. In cells, whenthey are in a hotter environment, theparticles will move faster in and out of thecells, which will make the process ofdiffusion faster. On the other hand, whenthe temperature of the water in our lab wasdecreased, the diffusion process took a lotlonger to complete, since the particleswere moving lot slower. This is the samewhen cells are in a colder environment,the particles will not move as faster asthey would in hot environment. Therefore,the particles will move in and out of thecells lot slower.