× Didn't find what you were looking for? Ask a question
  
  
Top Posters
Since Sunday
8
s
5
a
2
1
1
1
1
1
1
1
1
New Topic  
Eva R Eva R
wrote...
4 weeks ago
Hello.,
 
I am currently in the midst of performing an experiment for my (AP) biology class. The project focuses on the concept of osmosis, using a scale-less egg (‘naked egg’) and different NaCl-solutions.
My teacher has already looked at my materials & method. I do wonder, however, whether the choices I have made, are correct.

I have decided to use 200 mL of water for each of my 6 scale-less hen’s eggs. I had first planned to create the following salt solutions:
0%, 0,5%, 1%, 2%, 3% and 4%.
Now I am wondering whether I should be using the following solutions instead:
0%, 0,5%, 0,9%, 1%, 2% and 4%.
Or completely different solutions, if these are wrong (I apologize if they are).

In case this question has already been asked somewhere else, I sincerely apologise.

I hope this query is alright. I am asking my questions here, because my teacher had already reviewed my current method, and I am afraid to bother him again.

I completely understand if answering this question is inconvenient or not possible.
Thank you anyway, for reading, in any case.

Best wishes and regards,

Eva R.

(English is not my first language. My apologies if anything is incorrect or unclear.)

Read 254 times
14 Replies

Related Topics

Replies
wrote...
Educator
4 weeks ago
Hi Eva

I have decided to use 200 mL of water for each of my 6 scale-less hen’s eggs. I had first planned to create the following salt solutions:
0%, 0,5%, 1%, 2%, 3% and 4%.
Now I am wondering whether I should be using the following solutions instead:
0%, 0,5%, 0,9%, 1%, 2% and 4%.
Or completely different solutions, if these are wrong (I apologize if they are).

Both %'s are fine. I don't see a major difference between your choices. Personally, I like the first one.
wrote...
4 weeks ago
Hello Bio_man,

Thank you so much for your reply! I appreciate it.

I wish you a good day/evening.

Regards,

Eva R.
wrote...
Educator
4 weeks ago
Same to you, feel free to update this topic should you have further questions.
wrote...
3 weeks ago
Hi!

As of now, I have been able to measure the weights of each of the eggs every two days.
I ended up using a few more eggs, as one of the ‘original’ eggs accidentally burst. After this, I decided to prepare some extra shell-less eggs. This is why I have measured some of the eggs two to three times, whereas the newer ones have only been measured once.

Now, however, I am a bit afraid that I have done something wrong. My current results are as follows:

(Below I have listed the contents of the columns that otherwise would not fit this page. They read from left to right.  I’m sorry if this is unclear).

Egg number - weight right after the acid treatment - weight after two days in salt solutions - weight after four days in salt solutions - weight after six days in salt solutions - percentage salt in solution (w/v) - grams salt in solution

1   89 g   95 g   96 g   96 g   0      0,00
2   89 g   91 g   94 g   94 g   0,5   1,00
3   86 g   94 g                         0,9   1,80
4   94 g   97 g   99 g   100 g   1,0   2,00
5   94 g   98 g   100 g   100 g   2,0   4,00
6   88 g   90 g   92 g   92 g   3,0   6,00
7   82 g   85 g   87 g                   4,0   8,00
8   88 g   92 g                      32,0   64,00

The eggs (those in the hypertonic solutions) that I had hypothesized to shrink, have not. Instead, all of the eggs have all grown (even the egg in the 32,0% solution).

I hope this table translates correctly on this website. If this is not the case, this is my fault, and I would gladly try do fix the issue. Sorry!

Thank you again.

Best wishes (and happy holidays, of course!),

Eva
wrote...
Educator
3 weeks ago
Hi Eva, it's OK, these things happen

Let's look at the theory. If the egg is placed in high salt concentration bath, the % of water inside the egg relative to the solution it sits in is higher. Since the shell is permeable to water only, the water will be drawn out, causing the eggs to shrink. You're experiencing the opposite, which is strange. How did you prepare the salt bath? How much salt was added relative to water?
Source https://biology-forums.com/index.php?action=gallery;sa=view;id=307
wrote...
3 weeks ago
Hi,

Thank you for your response!

First, I began the experiment by placing each egg in regular cleaning vinegar for two days. After this initial treatment, I noticed that the now shell-less eggs had absorbed a (perhaps significant) amount of the vinegar.
I then rinsed the eggs, weighed them, and prepared the salt baths using regular table salt (containing NaCl, iodine) as my biology teacher suggested. 

I took 200 mL of water and added:

0% : 0 g of salt
0,5% : 1 g of salt
0,9% : 1,8 g
1% : 2 g
2% : 4 g
3% : 6 g
4% : 8 g
32% : 64 g

I was unsure about these amounts. Sorry if this is incorrect.

Thank you again.

Regards,

Eva
wrote...
Staff Member
3 weeks ago
Hello everyone

According to this document, what you're experiencing is normal. The egg is getting fatter because it's not salty enough
Attached file
You must login or register to gain access to this attachment.
- Master of Science in Biology
- Bachelor of Science (Biology)
- Bachelor of Education
wrote...
3 weeks ago Edited: 3 weeks ago, Rose_
Hi,

Thank you for your response. I really appreciate it.

The main experiment’s question is what percentage salt (NaCl) solution is comparable to that of a hen’s egg. Comparing animal cells to human cells, I hypothesized that this percentage would lie somewhere around 0,9% (which is a guess, and I don’t know for sure). The highest percentage spoliation I used was 32%. Even with this one the egg did not shrink (though I could of course have done something else wrong, sorry!).

Thank you again!

Regards,

Eva
wrote...
Educator
3 weeks ago Edited: 3 weeks ago, bio_man
Quote
1   89 g   95 g   96 g   96 g   0      0,00
2   89 g   91 g   94 g   94 g   0,5   1,00
3   86 g   94 g                         0,9   1,80
4   94 g   97 g   99 g   100 g   1,0   2,00
5   94 g   98 g   100 g   100 g   2,0   4,00
6   88 g   90 g   92 g   92 g   3,0   6,00
7   82 g   85 g   87 g                   4,0   8,00
8   88 g   92 g                      32,0   64,00

Look at your control. It is correct.

An egg submerged in distilled water will gain water by osmosis because the egg has greater solute concentration than the surrounding water. The egg is hypertonic to its environment. The water flows across the membrane to the side having more negative water potential.

In tap water, an egg’s concentration of water (90%) is lower than tap water, hence you're expected to see it expand, as you see in your results.

Therefore, anything more than 10% salt concentration should make your egg shrink in size.

8   88 g   92 g                      32,0   64,00

Row 8 is the only instance where the percentage of water is less outside than inside. Hence, you'd expect a movement of water to flow out of the egg and shrink. But we don't see that

The main experiment’s question is what percentage salt (NaCl) solution is comparable to that of a hen’s egg. Comparing animal cells to human cells, I hypothesized that this percentage would lie somewhere around 0,9% (which is a guess, and I don’t know for sure). The highest percentage spoliation I used was 32%. Even with this one the egg did not shrink (though I could of course have done something else wrong, sorry!).

This would need to be determined from your experiment results. When do your results show no change in size from one day to the next? This is how you'll know the solute concentration of the egg. Unfortunately, none of your results demonstrate this. It is well-known that water constitutes about 90% of this, with protein, trace minerals, fatty material, vitamins, and glucose contributing the remainder.
wrote...
3 weeks ago
Hi,

Thank you so much for your feedback and the information.

Would it perhaps help if I were to repeat the experiment using distilled water instead of tap water? Or is something else the matter?

Sorry for all the questions. Thank you for your time.

Regards,

Eva

wrote...
Educator
3 weeks ago
No, that's not necessary. What I recommend is that you keep in your report 0% salt, 1% salt, 4% salt, 10% salt, and the 32%, and get rid of the rest.

Since this is a well-known experiment, I would make up some numbers for 10% and 32% showing that the egg did in fact shrink at 32% and the weighed slightly less @ 10%

Does that make sense?
wrote...
3 weeks ago
Hi,

Thank you again for your response!

Okay, thank you. I will try that.
Because I am interested in what went wrong, I will also try to look for possible reasons behind this mishap. Is there anything that could have caused this? Or is this complex to figure/point out?

Thank you again! (Apologies for all the messages.)

Regards,

Eva
wrote...
Educator
3 weeks ago
You're welcome, we're happy to help.

If you have time, I would do two more trials, one at 10% and another at 25%. I don't know what went wrong, honestly.

When you make your salt solution, at 50 grams of NaCl into 200 mL of (preferably) distilled water. That should make 25%. Similarly, to make 10%, add 20 grams of NaCl into 200 mL of distilled water. Stir it thoroughly, and also rinse-off your shell-less egg with distilled water so that all the vinegar has been removed.
  New Topic      
Explore
Post your homework questions and get free online help from our incredible volunteers
  102 People Browsing
 278 Signed Up Today
Your Opinion
What's your favorite funny biology word?
Votes: 50

Related Images
 5844
 126
 155