Green Chemistry and Nanochemistry
Green Chemistry and Nanochemistry tests the twelve principles of green chemistry, atom economy, green solvents and the synthesis, properties and applications of nanomaterials.
Core rules
- Green chemistry designs processes that reduce or eliminate hazardous substances at source.
- Atom economy = (molar mass of desired product / total molar mass of reactants) x 100.
- Twelve principles include waste prevention, atom economy, less hazardous synthesis, safer solvents, energy efficiency, renewable feedstocks, catalysis and biodegradability.
- Nanomaterials have at least one dimension in the 1-100 nm range; top-down and bottom-up are the two synthesis routes.
- Nanoparticles have a high surface area to volume ratio, which changes reactivity, optical and catalytic properties.
Worked example
Calculate the atom economy for making ethanol by hydration of ethene: C2H4 + H2O → C2H5OH. Molar masses: C2H4 = 28, H2O = 18, C2H5OH = 46. Atom economy = 46/(28 + 18) x 100 = 46/46 x 100 = 100%. Reasoning: all reactant atoms appear in the product, so there is no by-product.
Traps
Confusing atom economy with percentage yield, using the mass of all products instead of only the desired product, and calling any fine powder a nanomaterial. The 1-100 nm size criterion is essential.