Diaper lab

Purpose- To find out how much urine sodium polyacrylate (waterlok) will absorb times it’s own weight.

Procedure- The first step in the process of this lab is to get the necessary equipment required for the experiment. The required materials are: safety glasses, one burette, one 200 ml flask, one 100 ml graduated cylinder, one beaker, one water bottle filled with distilled H2O.

After both Matt and I had all of the equipment ready, we needed to start making our own urine. The average human being’s urine has a density of 1.002-1.035 g/ml. In order to recreate this density, you will need to add .9 g NaCl to every 100 ml distilled water you use. We decided to make 200 ml, which means we added 1.8 g NaCl to our flask. To measure out the 200 ml, we used a 100 ml graduated cylinder filling it twice while making sure to read the meniscus correctly.

In our experiment, we were instructed to use between .1 and .2 g sodium polyacrylate. We measured this out accurately with and electric scale provided by Mr. Klos. After Matt had put the recently measured waterlok into a beaker, I had finished filling the burette up. To do this accurately, I first rinsed it out with distilled water, making sure the cock stop was turned parallel with the ground so I didn’t leak all over. Next, I emptied some of the fake urine into the burette and carefully coated the inside. After that, I ran the remaining urine out of the burette tip.

Now we were ready to begin the experiment. Simply place the beaker containing the waterlok underneath the burette filled with the substituted urine. Lower the burette down so that the tip is well inside the beaker containing the sodium polyacrylate. Now simply turn the cock stopper so that it is parallel with the burette and let the fake urine flow into the beaker. As the waterlok absorbs the urine, a judgement call must be made on when to stop the flow of urine from the burette. The cock stop should be shut off when the sodium polyacrylate can no longer hold any more fake urine.

Once we had read how many ml of urine you emptied into the beaker, we were able to tell how many times it’s own weight the waterlok held. To figure this percentage, simply take the amount of urine emptied (in ml) divided by the amount of waterlok used.

 Repeat this procedure at least 3 times.

                        

Googoo  Matt, Waaa  Nick,  my diaper needs more water lok, how about yours?              

Data- 

 Trial          g Waterlok ml             Urine Absorbed              % x Own Wt.

*1

.15

12

80

*2

.14

11.55

82.5

3

.15

9.15

61

4

.15

9.15

61

*5

.13

10

76.9

*6

.14

9.5

67.8

*7

.14

9.2

65.7

*8

.14

9.1

65

*9

.14

9.6

68.5

*10

.14

9.2

65.7

*11

.14

16

114.29

* These trials are thrown out due miscalculation or human error

Observations- During the time that we were doing this lab we observed the urine gradually draining from the burette and dripping into the beaker containing the waterlok. When the urine fell from the burette and made contact with the waterlok the waterlok started to react by gelling up very quickly and holding the urine in one place so it wouldn't be so runny. When we picked the beaker up to see if there was enough urine added to the waterlok we saw that sometimes the gelled waterlok stayed in the same place in the beaker and we had to add a little more urine. Also, we sometimes added too much urine to the sodium polyacrylate. This made the solution runny and gave the impression that it would run down your leg if it were actually in a diaper. We also observed that waterlok absorbs water in the air if left out uncovered. One of our tests was contaminated by this sample of waterlok.

Conclusion- This experiment was very easy. However, the easy part was measuring out the substances and taking readings. The difficult part came when it was time to judge how much more or less urine the waterlok could hold. This aspect was based totally on a judgment call with little information to guide us. The only clue as to how close we were to having a correct percentage number was when we nagged you and finally got the friendly hint of between 40 and 80% times it’s own weight. Again, the judgement call came into play and we were forced to use our gut instinct.

With the data that we recorded, many of our trials were thrown out. Most of these trials were too runny, by our judgement. Our final decision was that sodium polyacrylate (waterlok) holds urine 61% times it’s own weight. That number was our lowest and most common, compared to the rest of the class. However, we did have a majority of trial resulting with the percentage around 65%. We decided to throw these out again due to our mutual feeling and also with comparison with the rest of the class. You might ask why we didn’t average these numbers together, but the fact of the matter is that a higher

being spoke to us and told us to use the 61%. So there you have it. According to Matt Tainter and Nick Lallas, waterlok holds 61% urine times it’s own weight.

Now, our percentage number may not be right. In fact it could be way off, but from the hints that we were given and discussions with the rest of the class we think it is pretty darn near close. That doesn’t mean that we could have screwed up somewhere either. Maybe Matt or myself read the meniscus wrong, or the density or our fake urine was way off. Both of these scenarios contribute to both a contaminated experiment and a wrong answer. On our final trail, the waterlok had been sitting out all night and all day. During that time it had absorbed plenty of water from the air. After the water had been absorbed and the waterlok dried out, it could hold much more urine than before. We found that out when our percentage read 114% times it’s own weight.

To add simplicity to this experiment, it is definitely nice to mix the fake urine right the first time. At the same time, a little information ahead of time regarding the fact that the flasks and beakers are not as accurate as the graduated cylinders are. Hint hint. That simply little bit of information would have saved us a small amount of time, and we would have been able to turn this in two days ago.

You said that you wanted a meaty conclusion. One that talks about how you got your answer and why you stuck with it. You also wanted to know about things we would change next time or errors we could have made this time. I explained all of those to the best of my ability and still have the feeling that this isn’t meaty enough. So, to spice things up, make them a little more interesting, cause your mouth to water, I include this last bit of information: