Three groups of drugs are used to reduce the stickiness of platelets, thus preventing platelets from clumping together to form platelet plugs. The anti-platelet drugs are most effective in preventing abnormal blood clots from forming in arteries (as opposed to veins). Aspirin and dipyridamoleâ (Aggrenox).
In order to react, colliding molecules must have a total kinetic energy equal to or greater than some minimum value [Figure 14.13(b)]. The minimum energy required to initiate a chemical reaction is called the activation energy, Ea. The value of Ea varies from reaction to reaction.
Determining the Activation Energy of a Reaction. The Activation Energy of Chemical Reactions. Only a small fraction of the collisions between reactant molecules convert the reactants into the products of the reaction. This can be understood by turning, once again, to the reaction between ClNO2 and NO. ClNO2(g) + NO(g) NO2(g) + ClNO(g)