Shapes of Molecules

The shape of a molecule determines many of its properties; For example: C4H10 is the formula for 2 separate molecules n-butane and isobutene Melting Point    -138°C                   -159°C Boiling Point     -0.5°C                    -12°C Enzymes—shape compatible with those molecules whose reactions they promote i.e.  the enzyme sucrase breaks down the sugar molecule sucrose The shape of a…

Rate Laws and Order of Reaction

Chemical reactions only take place when there are collisions between reactants Depends on: Number of collisions per unit time Fraction of collisions which are successful There is a relationship/pattern between reaction rate and the factors that affect it This pattern can only be determined empirically (through experimentation) Rate Law Empirical evidence supports that the reaction…

Snell’s Law Questions/ Answers

Indices of Refraction for Various Media: Medium Index of Refraction (n) Air/vacuum 1.00 Ice 1.31 Water 1.33 Ethyl alcohol 1.36 Vegetable oil 1.47 Acrylic 1.49 Glass 1.52 Diamond 2.42 1. Using Snell’s law, determine the constant when the angle of incidence and the angle of refraction are: a) 50˚ and 30˚                       b) 30˚ and 18˚                      …

ORGANIC REACTIONS

To simplify the multitude of possible combinations of reactants, organic reactions fall under specific types. Combustion Substitution Addition Elimination Oxidation/reduction Condensation (dehydration synthesis) Hydrolysis (hydration) Polymerization Another tool to simplify your task of predicting products is to remember that functional groups will always react the same way. e.g. all 1o alcohols will react the same…

Valence shell electron pair repulsion (VSEPR) theory

Valence shell electron pair repulsion (VSEPR) theory is a model in chemistry used to predict the shape of individual molecules based upon the extent of electron-pair electrostatic repulsion. It is also named Gillespie-Nyholm theory after its two main developers. The premise of VSEPR is that the valence electron pairs surrounding an atom mutually repel each…