PLS HELP - URGENT

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RS516
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PLS HELP - URGENT

Post by RS516 »

Hello,
On the Waste Not Want Not page (building an MFC), I am wondering about the Making salt bridges part. What tubes are they talking about? I thought the agar solution was simple poured into the petri dish and put into the fridge.

these are the instructions:

2) Cover one end of the tube section from the compression fitting securely with aluminum foil. Repeat with the tubes from all of the compression fittings. Place all tubes, open end up, vertically on the petri dish and then set it aside.

7) While the solution is still warm, carefully pour the solution into the tubes in the petri dish. If the tubes leak, tighten the foil and refill them. Once the tubes are filled and stable (i.e. haven't fallen over, leaked liquid, etc.) for 10 minutes, carefully move the petri dish to the refrigerator. Let the tubes sit in the refrigerator overnight. These tubes are the salt bridges.


can someone pls explain to me abt what the instructions are asking?
Thank you,
:)
bfinio
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Re: PLS HELP - URGENT

Post by bfinio »

Hi - the tubes the directions are referring to here are the ones shown in Figures 4 and 5, connecting the two containers. They are removed in step 12 of the "Building the Anode and Cathode Chambers" section, leaving them free to use in the "Making the Salt Bridges" section - you don't need any separate tubes. Hope that helps!
RS516
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Re: PLS HELP - URGENT

Post by RS516 »

Thank you so much!
RS516
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Re: PLS HELP - URGENT

Post by RS516 »

Also, is it possible to use some other container if I don't have a Petri dish?
AmyCowen
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Re: PLS HELP - URGENT

Post by AmyCowen »

Hi - You can use another dish. You want, ideally, a sterile, flat-bottomed container that will be easy to move around. It is a good idea to sterilize whatever you use with boiling water or by wiping it with rubbing alcohol before using it.

Amy
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RS516
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Re: PLS HELP - URGENT

Post by RS516 »

Hi,

for the Making Salt Bridges step,

Measure 300 milliliters (mL) of water and pour it into the pot.
Using the scale, measure out 30 g of agar. Set the measured agar aside. Now measure out 6 g of salt.
Place the pot of water on the stove and bring it to a boil. When the water is boiling, add the agar and stir it with the glass rod until it is dissolved.
Once the agar is dissolved, take the pot off of the heat and add 6 g of salt. Stir with a spoon until the salt is dissolved.


do we follow science buddies measurement for making agar, or do we follow the instructions given on the agar we bought?
We tried making the agar according to science buddies and it turned out very doughy and stiff the second we mixed both the agar and water in.
If we do follow instructions given on the agar we bought, how much salt do we put?

Thank you,
:)
RS516
Posts: 8
Joined: Sun Feb 13, 2022 8:56 pm
Occupation: Student

Microbial Fuel Cell - pls answer as soon as possible

Post by RS516 »

Hi,

for the Making Salt Bridges step,

Measure 300 milliliters (mL) of water and pour it into the pot.
Using the scale, measure out 30 g of agar. Set the measured agar aside. Now measure out 6 g of salt.
Place the pot of water on the stove and bring it to a boil. When the water is boiling, add the agar and stir it with the glass rod until it is dissolved.
Once the agar is dissolved, take the pot off of the heat and add 6 g of salt. Stir with a spoon until the salt is dissolved.

do we follow science buddies measurement for making agar, or do we follow the instructions given on the agar we bought?
We tried making the agar according to science buddies and it turned out very doughy and stiff the second we mixed both the agar and water in.
If we do follow instructions given on the agar we bought, how much salt do we put?

Thank you so much!
:)
AmyCowen
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Re: PLS HELP - URGENT

Post by AmyCowen »

Hi - It sounds like you need to try this step again, being sure you doublecheck everything and follow the directions step by step.

1. You should follow the directions in the procedure. Those directions are written specifically for the project.

2. Double-check that you used the correct amount of water, agar, and salt.

3. Make sure your water was boiling (as directed).

4. After bringing the water to a boil, you are then instructed to add the agar and stir (and continue stirring) until it dissolves. Did you do that?

5. Also make sure you have the right substance. If you bought the agar in a grocery store, it might be called agar agar powder. That is what you need. Make sure you are not using gelatin or some other substance.

Please note that posting multiple times isn't necessary.

Amy
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RS516
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Re: PLS HELP - URGENT

Post by RS516 »

Thank you!
RS516
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Connecting an MFC to an LED

Post by RS516 »

Hi,
Im not sure if i posted this in the right place, but i was wondering if it was possible to connect a 2 chambered MFC (microbial fuel cell) to an LED light?
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Re: PLS HELP - URGENT

Post by MadelineB »

Hello RS516,

Since this post seems to be related to your previous posts about MFCs, I've merged it so there is a single topic thread. This helps the experts who have been helping you can see that you have posted a related follow-up question.

Just to make things more complicated (sorry!), I am also cross-posting this topic to the Grades 6-8 Physical Sciences, so those experts can add their comments.

Thanks for keeping your posts on this MFC project in the same topic thread and best of luck with this fascinating project!

Madeline
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RS516
Posts: 8
Joined: Sun Feb 13, 2022 8:56 pm
Occupation: Student

Re: PLS HELP - URGENT

Post by RS516 »

Thank you
:))
bfinio
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Re: PLS HELP - URGENT

Post by bfinio »

Hi - we have not tested this particular project with an LED so cannot say for sure. The smaller MFC available in a kit does not generate enough power to light an LED continuously. It has a special circuit that stores up charge and blinks the LED intermittently. Since this MFC is larger it might be able to light an LED. You might have the most luck with a red LED (which requires lower voltage than other colors) and one that is labeled as "super bright" like this, as it will be easier to see: https://www.jameco.com/z/LUR3833-Jameco ... 33526.html
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