Water to fuel to Water project

sababa123 · Post by **sababa123** » Fri Mar 29, 2013 10:01 am

In the procedure Technical note #1 is using ohm formula but why does it 'drop' 30 v?? And in technical note #2 how do you calculate the ideal efficiency?

deleted-90600 · Post by **deleted-90600** » Sat Mar 30, 2013 1:19 am

Hello,
The batteries are providing around 36 volts to the circuit, but you want to reduce or "drop" the voltage by 30 v with the 10,000 ohm resistor to keep the current constant. This is where Ohm's law comes in - in Technical Note #1 they must assume that 30 v will be dropped between the batteries' voltage and what the voltmeter reads in order to calculate the current: 3 mA. The equation I = V/R can also be written as I x R = V where V means voltage, but in this case, voltage drop.

In Note #2, they have established that 1.23 v is just the right amount of voltage for an ideal cell with no overpotential to maintain the current of 3 mA. If the cell were perfectly efficient, you would read 1.23 v on the voltmeter, so the calculation of efficiency would be (1.23 v/1.23 v ) x 100% which equals 100% efficiency.

I hope these explanations answer your questions. Working with circuits can sometimes be confusing, so I wish you luck as you continue your project!

sababa123 · Post by **sababa123** » Sun Mar 31, 2013 9:14 am

Why do you have to connect a small piece of wire????

"f. If you are using the type of breadboard shown on the left in Figure 1, connect a small piece of wire between a position in the same row as the voltmeter/multimeter's negative lead (7j is used in Figure 1) and the ground bus (the far right "-" column)."

deleted-90600 · Post by **deleted-90600** » Sun Mar 31, 2013 11:27 am

Hello,
The reason why you need to connect a small piece of wire between the negative lead of the voltmeter and the negative end of the series of batteries when using the breadboard shown on the left is because that breadboard has power rails, while the smaller one on the right does not. The blue column labeled "-" is the ground bus and all the sockets in that column are connected vertically. The sockets in the center labeled with letters are connected horizontally. You need to make a connection between the row where the voltmeter lead is and the column where the negative end of the batteries is with the small piece of wire. You can look at the Science Buddies breadboard guide, which has a helpful illustration of how the sockets are connected.
https://www.sciencebuddies.org/science- ... background

sababa123 · Post by **sababa123** » Mon Apr 01, 2013 9:41 am

When adding the catalyst it says not to stop until the voltage does not change. I did about 6 times and then the lead turned black. Why is this?

kgudger · Post by **kgudger** » Mon Apr 01, 2013 2:40 pm

Hi sababa123:

You will notice that I have combined all of your posts into one post. Please do not make a new post with each new question. Please add your new question(s) to the existing thread.

The answer to your question is in the experiment write up:

The cobalt-based catalyst will begin to electroplate onto the anodic (connected to + side of the battery) nickel electrode. As the catalyst film grows, you will see a brown film growing on the anode.

If you want to know more about electroplating, you can search the internet and find good answers.

Keith