Hi Lakshita,
I am glad to see you have a whole set of new questions for me about the SAP experiment. First off, though, I am trying to think of a new experiment for you to do using the orange peel mixture (OPM) SAP so that you are not copying the same thing that Kirin did. Verifying someone else’s experiment is ok and necessary in science, but a researcher always adds something different to the mix that provides additional data as well as confirms the existing data. One very important feature of research that seemed to be missing from Kirin’s experiment was the use of statistical tests of the data. A scientific paper would never be published without these tests as they are the only way that a researcher can prove with 95% confidence that a difference between two experimental results is real or just occurred by chance. For example, she measured the water retention of SPA as 74.7% and that of OP as 76.1%. These values are very similar, and just because the water retention of OP is 1.4% higher does NOT prove that it is a better SAP. I am betting that there is no difference between the two SAPs, but if you repeated the experiment many times you might be able to prove that OP was better—or, it might turn out that SPA was slightly better. You cannot know without doing the test.
The only way to prove that a difference is real and not due to chance is by statistical tests. In order to do these tests, you will need to do the water retention experiment at least 3 times and preferably 5 or more times. Afterwards you calculate the average of the water retention readings for both SPA and OP and then you perform a statistical test to determine what is called the standard deviation and standard error of the mean. Now, I suspect that you have not had lessons in statistics yet—is that true? So, you will have no idea what I am talking about, but believe me this IS important and the only way to prove a hypothesis. You can do some self-education by watching You Tube videos that explain about this aspect of statistics and I can help explain it to you so you understand. Then you will be ahead of your other classmates in being able to use something that modern science could not exist without.
1. Do you recommend me comparing Sodium polyacrylate SAP vs different Orange peel variables which are orange peel solution, orange peel mixture and orange peel powder?
Or just Sodium polyacrylate SAP vs orange peel mixture SAP?
I think that just comparing SPA with OPM is sufficient.
2. In this project, Kiara performed three different type of experiments.
- Water absorbing ability
- Effect on soil moisture
- Effect on growth of an plant and the moisture of the plant’s soil
I guess performing third experiment is difficult during winter as it aims at plant growth. Please suggest if I need to perform these 3 different experiments?
Once you let me know on this, I will go over these experiments in details and post my questions.
As you said, doing plant growth experiments in winter might be difficult. On the other hand, if you have a fairly warm room inside your house where you can set up an LED grow-light, then you can do the experiment. Improved growth of a plant is really the key experiment, so I would recommend setting up an indoor plant growth area. Growing plants inside over the winter is a very satisfying activity. I live in northern Maine where the winters are long and very cold and I have one room where I have three banks of LED lights set up above a long table with heating pads to keep the temperature constant. I am able to grow lettuce, spinach, cabbage, flowers, herbs and seedlings to transplant in the spring. So, give this some thought and see if you can set up a plant growth test for the SAPs.
3. Does science fair allow three experiments to be performed in a project? Why I am asking this is Independent variables will be different types of SAPS, but dependent variable will be different for each experiment. Please let me know your thoughts.
Oh, sure—you can always do more than one type experiment. Research scientists typically include six or more different experiments in a research project in order to provide additional data to prove or disprove their hypothesis. The statistical tests are applicable to any experiment as long as you can calculate a mean and standard deviation.
Here is where I think you could add something new to the project. Instead of testing just one concentration of SPA against OPM in the plant growth experiment, you could do three concentrations—say, low, medium and high [amounts to be decided later]. This is necessary, because a farmer wanting to use the OPM for a crop in the field will need to know how much of the product to apply. He will want to use enough to improve the water retention properties of his soil, but not use too much, which would be expensive and wasteful.
4. How will I mention control variable for Water absorbing ability experiment?
Your control will be no SAP added.
5. Regarding constants: I have some in my mind as - Amount of different types of SAPs tested (5 grams), Amount of water added (200 ml), Atmospheric environment when the experiment is performed, Amount of time (??)
Please let me know how to list out the constants if I am going to perform various experiments. Confused how this is allowed in the science fair.
The water retention experiment should be done at approximately the same temperature each time in case this variable might affect it. Use a digital thermometer with a probe to read the temperature. I don’t know how Kirin decided on using 5 g of SAP to 200 ml of distilled water. This is something you could vary in order to see what happens. You need to add enough water so that it exceeds the amount that the SAP can hold, and then pipet off the excess [Carolina Bio has cheap transfer pipets that you can use for this].
6. Regarding the water absorbing ability experiment, I understood what you mentioned. Find below my clarifications on this.
- We have to take 5 grams in small cups and add 200 ml of water for each SAP. Is that correct. I am confused since you mentioned we have add water to add water to the cup until the SAP cannot hold any more.
Yes, that is the only way to compare the two materials accurately. Also, you must use distilled water for the test, as the various minerals in tap water can alter the absorption. According to descriptions on the web, SPA can absorb as much as 800 times its weight in water:
https://www.cmu.edu/gelfand/education/k ... owder.html
Now, 200 ml of water weighs 200 grams, which is only 40 times the weight of the SPA powder used in Kirin’s experiment. You need to try this and keep adding measured amounts of water to 5 g of SPA until you are sure that it cannot hold any more. Then you need to do the same for the OPM. Try to have the water at the same temperature each time and be sure you measure the time that the SAPs are in contact with water. I don’t know how long it will take for maximum water retention. SPA seems to absorb water very quickly at first, but as it approaches saturation the time may increase.
- Actually amount of water and amount of SAP should be same in order to test water absorbing abilities of different SAPs right?
No. Sodium polyacrylate can absorb 100s of times its own weight of water. That’s why you need to add an excess of water to make sure the SPA and OPM are fully saturated—then pour off the excess.
- So after what time should I measure the weight again? Will the absorbing happen in minutes or should I leave for hours? Time is constant.
I don’t know. You will have to test this. Do some more reading about absorbent polymers online and try to find out more about the timing. As I said, I think the water absorption is rapid at the start but may slow down later. And the rate of absorption of SPA may be different from OPM. Doing experiments is not that simple. You must pay attention to all these variables such as time and temperature and water type.
- Should I weigh along with left out water too? I am confused how to weigh.
Gs will be weight of (water+water absorbed SAP) – (weight of small cup) ? Please let me know how to weigh?
The key measurement here is the volume of water that a certain weight of SAP can hold. You can express that simply as weight of water, or you can calculate it as a percentage of the weight of the SAP. Always weigh your cups first and write the weight on them with a sharpie. This is THE most important measurement and it is going to be the most difficult to do accurately. That is why I said for you to run the water retention experiment as many times as possible so that the average is as accurate as possible.
7. Regarding the procedural steps for preparing various orange peel variables:
Yes will make sure to use past tense always. Also be careful not to capitalize words that are not proper names as Kirin did multiple times in the slides. It makes them look unprofessional.
- Three oranges were peeled including as much pith as possible. [Source of the fruit?]
Source you mean the type of oranges I am going to use right? Yes. Different types of orange may have peels with different absorbent properties and organic might give different results from conventional. Also, describe the source of your avocado. Organic might be best.
Do I need to take only orange peels and pith and discard the actual fruit right?
Correct. Only peels and pith.
- 15 ml of lemon juice was added and left for one hour [Fresh-squeezed lemon juice or bottled?]
I am planning for bottled organic lemon juice. I will include the type of it in my procedure once selected. So all these would be part of constants right?
Yes. Always use the same test ingredients each time.
- 100 ml of water [Did you use distilled water?] was added to the peels and they were cooked ['Cooked' is a nonscientific term so don't use it. The proper way to say this is that the mixture was heated at a certain temperature, or boiled] for 45 mins
I am planning to use distilled water. And boiled until the water evaporates and peels are cooked. I will make sure to include the exact time after my procedure. Please correct me if I am wrong.
That is correct.
- The mixture was strained overnight [Through what? A sieve, a coffee filter?]. 60 g of the solution serves as 'orange peel solution'.
I am using sieve. This step gives me one variable 'orange peel solution'
OK. That will work.
- The heated orange peels were finely cut and added to finely cut avocado peels, both left in sun for 14 days
- 60 g of the sun dried peels were added to 80 ml of the strained liquid and heated for 20 mins in an oven at 180 degree C. The crushed peels formed orange peel powder
What material should I use to measure ml of liquid?
First off, you do not measure with a ‘material’. You use a container, preferably a graduated cylinder from your lab that is marked off in milliliters. You can use an ordinary glass cup measure that is graduated in ounces and milliliters, but it is not accurate enough
This step gives me second variable orange peel powder.
- 40 g of the crushed powder was added to 20 g plain sun dried avocado and peels to form the orange peel mixture
This step gives me third variable orange peel mixture.
Good luck! Post again with your ideas about how to complete this project and your additional questions.
Sybee
