H2O penny lab and scientific method

Transcription

1 Student Name H2O penny lab and scientific method By: Student Name 7th science honors combs 9/12/12 Comment [SWC1]: Check formatting for cover page

2 I. In the experiment of the drop on a penny, we first had to state question or problem. My group would like to investigate how many drops of each variable water, 25% soap and water, and 50% water and soap. Can we put on the penny with an eye dropper before the liquid water tension breaks? Next we had to state out hypothesis and ours was, if the same amount of each different substance is dropped on the penny then soap and water liquid will overflow because soap breaks water tension and causes it to go flat. Next we needed to figure out a procedure for the experiment we were thinking that we should state the variables and constants first. So the independent variable is the substances dependent is the amount of drop on the penny and the constants or controls are the pennies side, substance, temperature of substances, same student, soap, and water. Or materials we need are a penny, pipettes or eye droppers (three), water, water with 25% soap, and water with 50% soap. First we start with a clean penny, then we place the penny on a dry spot on the paper towel count the number of drops as you place drops of liquid on the penny until any amount of liquid runs over the edge of the penny. Then we clean the penny and repeat step 2. Lastly, we have to record our data that we collect from our observations. In the end when we looked at our data we had found that the average number of drops for the water was 14, the average number of drops for water and 25% is 16.3, and lastly the average for the water and 50% soap was I believe that our hypothesis was incorrect because we had stated that almost all the substances would break around the same amount but we were incorrect on our part. In conclusion the lab had gone well and our hypothesis was incorrect but that is ok because we all need to learn from our mistakes. Comment [SWC2]: Label the Abstract Comment [SWC3]: No pronouns Comment [SWC4]: Don t state that you had to state. In an abstract, you need to get straight to the point. Comment [SWC5]: Put what on a penny? Comment [SWC6]: Just summarize the procedure don t say that you needed to create one. Comment [SWC7]: Use the term not supported How much water, water 25% soap, and water 50% soap, can be placed on a penny before tension is broken and the water or substances falls off of the penny? II. Purpose Comment [SWC8]: Left justify Which substance water, water with 25% soap, and water with 50% soap will hold the most of that substance on the penny without it breaking tension off the penny? Take three trials then find the average of all three trials Comment [SWC9]: This is confusing see if you can reword it. Comment [SWC10]: Don t put this sentence here. III.

3 IV. Hypothesis- if the same amount of each different substance is dropped on the penny then the soap and water liquid will over flow because the soap breaks water tension and causes it to go flat. Comment [SWC11]: What do you mean by go flat? Do you mean to spill over? Independent- substance Comment [SWC12]: Don t forget your headings Dependent-amount of drops on penny Constants- penny side, substance temperature of substances, same student, soap, and water. V. Materials- 1. pennies 2. paper towels 3. pipettes 4. water 5. water with 25% soap 6. water with 50% soap Comment [SWC13]: Don t number and remember to use upper case Comment [SWC14]: Diagram goes after procedure, not before Water 25% soap and water 50% soap and water

4 VI. 1. Figure out what the problem is and what need to be tested state your hypothesis 2. Gather all materials in order to do experiment 3. Choose your fist variable to test either water, water 25%, or water 50% 4. Conduct three trials and record how many drops then find average 5. Repeat step four until all three variables have been tested 6. When finished look back on hypothesis and see if it s correct or incorrect and figure out why you think it incorrect if it s not correct. 7. Create graph about average drops and then write your conclusion Comment [SWC15]: Your procedure steps need to be about the experiment you re doing, not the setup. Look at the steps in the lab handout. VII. Liquid measured Trial 1 Trial 2 Trial 3 Average number of drops Water Water & 25% soap Water & 50% soap X. The formula we used was the formula for average and that s when you find the sum of all data and then divide it by how many numbers are in the data table. We collected data by having the same Comment [SWC16]: Where s your graph? & graph description? Comment [SWC17]: Don t put in the formula for average.

5 student each times do the drops. And as she did the drop the other two students counted how many Comment [SWC18]: No personalizations. drops were on the penny. Also, we cleaned the penny off after each time we tested. On the water 50% all the trials were in 20 s and mostly even. In the 25% the data was at most 3 drop away from each other. And on the water it was strange because the first time we got in the 20 s second we got 8 and there we got in the teens. I think that our hypothesis was incorrect because we had thought that all of them would be the same amount, that the soap would not make a difference on how much could fit on Comment [SWC19]: Be more specific about your data. Comment [SWC20]: Use not supported. the penny. But we were incorrect because the soap made the tension less so that more of the substance could fit on the penny without letting the substance fall of the penny. I think that were we had sources of error was after the 25% soap it had a lot of it fall of onto the Comment [SWC21]: Don t use I think paper towel and we cleaned it off as best we could with that paper towel but we did not clean it completely and we used the same wet paper towel. So I think this was an error because we didn t get all of the substance off before starting the next trial. If we were to do the lab again I think we would have a different student do it because the first trial was messed up. So I think we should get someone with a more sturdy hand. The tension of the water or substance on the penny was very interesting. The tension Comment [SWC22]: Don t include opinions. broke in different spots each time with new substances. So the water was the least on the penny before breaking tension. Then the 25% was the second least and the 50% was the most that could fit on the penny without breaking tensions. This is so because since the substance is thicker it can stay on the penny more without it breaking tension. Comment [SWC23]: What do you think this means? In conclusion the hypothesis that we had come up with was if the same amount of each different substance is dropped on the penny then the soap and water liquid will over flow because soap breaks water tension and causes it to go flat. This is incorrect because we thought that the liquid would go flat almost immediately with the soap plus water mixture but it did not. It took a full drops of it Comment [SWC24]: Why did you think this? before it broke tension on the penny. Our further research is water droplets don t form a skin but stick

6 to surface without tension breakage soap kills cohesion of the molecules (drops) and forms sheets. So, the drops will role and not slide because it only adheres with other water droplets. Comment [SWC25]: Spelling? VIII. Citations in APA format smith, M. (2009). Abraham lincoln on a penny. (1 ed., Vol. 1, p. 4). New York: iclipart. Retrieved from (2011). Paper towels. New York: Word Clipart Retrieved from towels&ex=1 (2002). eye dropper. Chicago, Illinois : Microsoft Word Clipart. Retrieved from Olsen, A. (2007, March 13). Measuring surface tension of water with a penny. Retrieved from No graph: -10 points