"Meto
and I are working on the experiment that I mentioned to you earlier. It is VERY
simple and fast (see below). If you have a chance, could you try to reproduce
it?"
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Setup
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Start of the experiment
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A home made determination of percent of oxygen in air" (Ibanez, Najdoski)
Introduction
"In the present experiment we present a novel, reproducible, fast, safe,
green, and low cost method based on the oxidation of dissolved Fe(II) in an
alkaline medium. It can be used with High School or General Chemistry students.
It is based on the fact that the reaction between Fe(II) and O2 to produce
Fe(III) is kinetically hindered at low pH, whereas at high pH it occurs in
the subsecond time frame."
Material
Photo
1: Tray, Digital Pocket Scale (Diamond Series A04, 0.01 g/70 g), drinking
straw spatula (S), 2 syringes (1 ml, 100 units), 1 piece of connecting hose
(|), 2 dropper bottles 10 ml labelled 0.2M FeSO4
and 2M NaOH, 2 film canisters with FeSO4.7 H2O
and with NaOH, funnel, distilled water. (Wear
goggles, use rubber gloves)
amount
of gas remaining at the end of this procedure."
Experiment
1. Make the solutions using the
technique described in www.micrecol/de/molE11.html.
2. "Draw 0.4 mL of a 0.2 M FeSO4 solution into the first
syringe. Now draw exactly 0.5 mL of air into the second syringe and then 0.4
mL of a 2 M NaOH solution. Connect both syringes through a 1-cm long piece
of a transparent and flexible rubber tube filled with 2 M NaOH. Avoid any
additional volume of air from coming into either one of the syringe barrels.
In a synchronized fashion, push one of the syringe´s plungers and pull the
other so as to mix well the contents of both. Repeat this movement several
times. Record the Write
down your observations,
try to explain
them.