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[APD] CO2 Diffusion Experiment #1 Results

I conducted the first experiment today. I ran an open ended 1/4" tube 
into the bottom of a 5-gallon bucket and used an inverted test tube and 
funnel to capture the bubbles. The CO2 bubble rate was set once and 
never adjusted. The bubble rate was verified before each step and was 
0.731 seconds per bubble, or 82 bubbles per minute.

Here are the results:

Number of bubbles collected to achieve 5 mL of gas vs. CO2 concentration

1) 123 bubbles at atmospheric equilibrium (<5 mg/L)
2) 124 bubbles at 30 mg/L
3) 129 bubbles at 170 mg/L

Trial #3 was run twice to make sure. First result was 129 bubbles, 
second result was 130 bubbles. I will leave the setup going until 
tomorrow to see if the solution becomes saturated overnight, and give it 
a go.

The concentration of dissolved CO2 does not seem to have any effect on 
the rate at which CO2 bubbles dissolve. Even a fairly small difference 
of a couple percent should have shown up here. Had the CO2 dissolved 
more slowly as the concentration in the water increased, each bubble 
would lose less CO2 on the way up and fewer bubbles would have been 
required to fill the test tube to 5 mL.

Jerry Baker
Aquatic-Plants mailing list
Aquatic-Plants at actwin_com