EPC - More Info -- Other

About things that have nothing to do with EPC

This Frequently Asked Questions page is intended to provide answers to things that have absolutely nothing to do with Noramco's Enterprise Project Control system or general project management... So enjoy.
If you have a question about project management, we have grouped our FAQs by category, so you can quickly find the answers to common questions. To jump to a specific category, simply click the category name on the left.

Q: How does a Lava Lamp work??
A: A container filled with clear or dyed liquid contains a non-water-soluble substance (the "lava") that's just a little bit denser (heavier), and has a greater thermal coefficient of expansion, than the liquid around it. Thus, it settles to the bottom of the container. A heat source at the bottom of the container warms the substance, making it expand and become less dense than the liquid around it. Thus, it rises. As it moves away from the heat source, it cools, contracts a bit, and becomes (once again) heavier than the medium. Thus, it falls. Heavy, light, heavy, light...

Q: What is Gortex?
A: Goretex is a dispersion-polymerised PTFE that is patented by W.L.Gore and Associates¹. It is classed as a stretched semi-crystalline film, and is produced by extrusion under stress (faster take-up rate than extrusion rate). The extrudate is stretched below the melting temperature, often in the presence of an aromatic hydrocarbon that swells the amorphous region, creating porosity. The hydrophobic nature of the PTFE means that liquid water is repelled from the pores, whereas water vapour can pass through. It is important to realise that once the PTFE pores are filled with liquid water, the fabric can allow liquid water to pass through until it is dry again. Thus Goretex-containing fabrics (such as Nomex/Goretex - which consists of an outer aramid fabric, a central Goretex layer, and a cotton backing) should never be used as protection from chemicals as many will pass straight through. Any water-miscible solvent (eg alcohol) can fill the pores, and then liquid water can displace it and continue to rapidly pass through until the fabric is fully dried out.

Q: What is the pH of Coca-Cola?
A: Phosphoric acid is an approved food-grade acid that is added to Coca-cola to provide some of the taste. When CO₂ is added to "carbonate" aqueous solutions, carbonic acid is formed. Through one of those unauthorized project experiments, a tin of coca-cola was cooled in a refrigerator to 7^oC and the pH of the sample measured over time. The pH electrode was not temperature-compensated, so a correction was applied.

Time	pH (when opened)	pH (corrected)
Initial	2.75 @ 7^oC	2.6
30 seconds	2.78 @ 7^oC	2.6
60 seconds	2.80 @ 7^oC	2.6
2 minutes	2.82 @ 7^oC	2.7
4 minutes	2.80 @ 7^oC	2.6

A sample was degassed in an ultrasonic bath for several minutes and the pH measured, and compared to a control sample maintained at the same temperature and time profile.

pH: degassed	pH: room temperature
2.52 @ 21^oC	2.50 @ 20^oC

So the conclusion is that the pH of Coca-Cola is approximately 2.5 - 2.7. Not surprisingly, the relatively weak carbonic acid from the dissolved CO₂ did not significantly affect the pH of the beverage. The aluminium beverage containers are lined with a thin polymer or lacquer coating to prevent the aluminium metal dissolving into the beverage.

Note that the differing flotation characteristics of cans of the normal versions of carbonated beverages like Coca-Cola (they may sink), and the diet versions (they may float), has nothing to do with the amount of CO₂ present. It is due to the increase in solution density from the few percent of sugar added to the normal version, while the diet version has only a few hundred ppm of an artificial sweetener that is much sweeter than sugar.

Q: I'm a little confused. What is pH anyway?
A: The pH scale determines the degree of acidity or alkalinity of a solution, but as it involves a single ion activity it can not be measured directly.

pH = - log₁₀ ( gamma H x m H )

where

gamma H = hydrogen ion single ion activity coefficient

and

m H = molality of the hydrogen ion

As pH can not be directly measured, it is defined operationally according to the method used to determine it. IUPAC recommend several standardised methods for the determination of pH in solution in aqueous solutions. There are seven primary reference standards that can be used, including 0.05 mol/kg potassium hydrogen phthalate as the Reference Value Standard. There is an ongoing debate concerning the relative merits of having a multiple primary standard scale (that defines pH using several primary standards, and their values are determined using a cell without a liquid junction) or a single primary standard (that requires a cell with a liquid junction).

Q: How much wood can a woodchuck chuck, if a woodchuck would chuck wood?
A: If this is a serious issue, you have too much time on your hands.

More questions?
Send an inquiry to: epcproject@noramco.com

References:
[1] Reagents for Organic Synthesis
L.F.Fieser and M.Fieser.
Wiley (1980-) ISSN 0271-6747(v1-7) ISSN 0271-616X(v8-)