Partial Pressure: in a mixture of gases, each gas behaves independently of the others (assuming the gases behave ideally).   The total pressure is then the sum of the pressures each gas would exert, if it were in the container by itself.  This law was first discovered by John Dalton, so is called Dalton's law of partial pressures.  It can be expressed mathemtaically as: P_T = P_a + P_b + P_c + ...

PET bottles: PET, short for polyethylene terephthalate, a commonly recycled household plastic material, represents approximately 30 percent of the plastic bottle market and is used to package a wide variety of food and beverage products such as soft drinks, juices, edible oils, liquor and peanut butter.   PET is valued for its clarity, toughness, and inpenetrability by carbon dioxide.  Many products are made from recycled PET including carpets, insulating material in garments and sleeping bags (fiberfill), and other bottles and containers, scouring pads, and auto parts.

Oxygen atoms have a greater attraction for electrons than do hydrogen atoms.  Because of the shape of a water molecule, this results in a polar molecule that has the positive charge oriented between the two hydrogens, with the negative charge oriented towards the oxygen.

Polarity effects: in a solution, the positive and negative charges on ions will tend to make the ions clump together, and cause the solvent molecules to line up in certain orientations.  Some solvent molecules, such as water are already substantially polar, and so will align themselves readily with ions.  Other solvents are quite "polarizable" – their electrons can be displaced by the charge on an ion, and so will themselves become slightly polar, even though in the pure solvent they are not.  Such polarity effects allow substances to form intermolecular attractions, and therefore solutions.

Polymer: long chain molecules, generally with a hydrocarbon skeleton, and other functional groups attached to give the materials specific characteristics.  Polyethylene is a polymer of ethylene linked end to end, with as many as 200,000+ atoms in the molecule.  Polymers are commonly called plastics. 

Potential energy: energy an object posseses because of its position.  Chemical bond energy is potential energy because it depends on the position of one atom with respect to another in a molecule.

Pressure: force per unit area.  The SI unit of pressure is Pascals (Pa); however, in most pressure measurements this will be expressed as kPa.   The atmospheric pressure at the Earth's surface is about 101.3 kPa.