In their experiment they maintained in MBL medium on a 12 hour light: 12 hour dark cycle (Philips 40 W fluorescent tube, white, 6500 K - see photo below) at 21°C. They found that a Cu2+ concentration of 7.9 x 10-7M (5 x 10-5 g/L, equal to 0.05 mg/L or 0.05 ppm) gave a 50% reduction in growth. to see what the MBL medium consists of (this may be too complicated for high school EEI). One question you need to sort out is how to measure algae growth (perhaps measure the absorbance in a spectrometer).
An interesting study by Drs Jenny Stauber and Mark Florence from CSIRO's, Division of Energy Chemistry, Lucas Heights Research Laboratories, Sydney, Australia found that copper ions depressed both cell division and photosynthesis in many species of algae notably the common freshwater green alga, "Chlorella" (). Reference: J. Stauber and T. Florence, 'Mechanism of toxicity of ionic copper and copper complexes to algae', 94, 511-519 (1987).
But how to get samples of these gases? You may have cylinders but you could produce H2 and CO2 by reaction (or let some dry ice sublimate); let some liquid nitrogen evaporate (or remove oxygen from air). And why not propane (BBQ gas) or butane (cigarette lighter fluid)? Remember that balloon gas is not just helium - it has 3% air mixed in with it. The main point is that the law holds for ideal gases but at atmospheric pressure and room temperature they won't be that ideal. And is the deviation from ideality dependent on the molar mass of the gas, or whether it is polar or non-polar, and where on earth do you get a polar gas from (HCl is too dangerous)? What range of temperatures will you use (consider liquid nitrogen, dry ice). What value will they give you for absolute zero when the V/T graph is extrapolated? How do you draw the line of best fit (is least-squares the best, does it give you the most accurate value for absolute zero?). And what is the volume of the gas in the apparatus? And what is the best way to measure temperature (of the gas as in the diagram, or of the water surrounding it)?
All you need do is to prepare a saturated solution at a desired temperature (with undissolved solid on the bottom) and keep it stirred for an hour or two. Let settle and take a sample of the supernatant liquid, weigh it, and evaporate the water (on a hotplate to dryness and then in an oven at 120°C for a day until mass is constant). Might take a day or two.
It may seem surprising but there are almost no journal articles by chemistry researchers on the effect of surface area on reaction rate - in industry or academia. Those that do relate to the area of catalysts rather than the main reactants (but that does suggest another EEI topic). The most recent paper as a stimulus for a high school chemistry EEI is one by industrial chemists Glenn Damon and Ray Cross from the Michigan College of Mining and Technology, Houghton, Michigan published in journal V28 (2) in February 1936. They reacted sulfuric acid with small squares of copper placed 2 cm under the liquid surface. However, to manipulate the surface area variable they varied the surface area of the solution exposed to the atmosphere. You could prepare a small circular piece of polystyrene foam (with a hole cut in the middle) and float it on the surface of the acid. This will give limited access of oxygen to the solution and hence limit the corrosion of the copper. It is a neat experiment and may give you a few ideas. to download it.
The biggest problem with chlorine as a sanitiser in swimming pools is that it breaks down and dissipates very easily under the sun's radiation. This can be fixed by adding cyanuric acid. Cyanuric acid (1,3,5-triazine-2,4,6-triol) is used as a "stabilizer" for chlorine in swimming pools and stops it breaking down so quickly in sunlight. On a bright sunny day, nearly all of the chlorine in a pool can be lost in less than two hours unless a stabilizer (like cyanuric acid) is present. The addition of about 30 mg/L (ppm) cyanuric acid to swimming pool water reduces destruction of the free chlorine by sunlight. In the stabilization process, a portion of the chlorine residual is temporarily bonded to the cyanuric acid molecule which protects the chlorine from the destructive effects of sunlight. The nature of this bond is such that the chlorine continues to be released as long as a demand exists.
An approximate idea of relative reactivities and induction periods (which must be considered as a mean value because factors such as light intensity, photosensitizers and antioxidants would alter these relative values for oils), is given below:
Your problem will be to ensure the same intensity of light gets through to the solution (yellow may not absorb as much as blue for instance). The image below shows the wavelengths of light most transmitted (passed) by each type of cellophane; this is called their "λTmax" (lambda T max), that is, the wavelength most transmitted. I did this on a spectrometer at Moreton Bay College but you could run them again if you can get access to a spectrometer. You would also need to know what % transmission occurs for each colour; I didn't do that. As a second IV you could try thickness: one layer, two layers etc of cellophane to see if the response is linear. Have fun!
Thus fatty acid composition, light, transition metal ions, oxygen pressure, presence of antioxidants, prooxidants, temperature, moisture content and distribuition were shown to affect the rate of the reaction.
Oxygen is evolved during photosynthesis but the conditions for maximum reaction rate are intriguing. It can be affected by many things, including: sunlight - its intensity and wavelength, temperature, CO2 and O2 availability, water (which closes stomata and restricts CO2), and any factor that influences the production of chlorophyll, enzymes, or the energy carriers ATP and NADPH, such as pH and Mg2+ availability. You could test the effect of pH and temperature. It sure won't be linear but how well your prediction (hypothesis) and results agree will be interesting. You could also try light intensity. If you don't have a "luxmeter" to measure intensity you could take advantage of the fact that as you double the distance of the light source to the plant, the intensity is quartered (but you'd have to cut out daylight). There are a lot of variables to control and complex biochemical reactions to examine.
Their role as auxiliary pigments in photosynthesis means they ubiquitously accompany chlorophyll, whose prooxidant effect they effectively tend to nullify.
Your research question could be along the lines of which vegetable oil produces the best biodiesel in comparison to commercial biodiesel? You can make biodiesel from soybean by the following method: Weigh accurately 20.0 g of soybean oil into a round bottom flask and add a few boiling chips, 6 mL of methanol and 1.2 grams of potassium carbonate and reflux for 25 minutes (at a low intensity). Then allow to cool. Add 18 mL of 1 M acetic acid to the flask and pour it all into a separating funnel. Allow the layers of the reaction mixture to separate overnight. Drain the lower glycerol layer into a waste beaker and collect the upper layer containing biodiesel into a tared beaker. Record the mass of collected biodiesel.
Chemical constituents of the water can change the ionic composition of the dialysate thus altering the concentration gradient in the dialyzer; react with constituents of dialysate or blood changing the chemical composition of the dialysate prescription or generating unwanted precipitates. This is just to highlight how important knowing how conductivity changes when precipitation occurs.