CHE 141 Lecture 1Current Lecture1.1 Reaction Rates Four factors influence the rate of reaction: 1. Physical state of the reactants -Reactions in the solid phase tend to be very slow while those in liquid and gas phases are generally faster. 2. Concentration of reactants-Increasing concentration of particles in a given volume increases the frequency of collisions3. Temperature -Average KE of particles increases with T, thus likelihood of collisions increases. 4. Presence of Catalysts-Catalysts accelerate reactions without being consumed in the process- A rate of change is the change that occurs in a given interval of time- An average rate of change is a rate of change measured from the starting time to the finishing time - Speed is a rate of change we use daily:o Speed= change in distance/change in time- The speed of a reaction is called the reaction rateo This is the rate at which reactants are consumed and products are formed during a chemical reactiono The reaction rate is expressed at the change in concentration of a reactant or product in a certain amount of timeo Reaction rate=change in concentration/change in time- We can write a rate of reaction for each reactant and product in a chemical equationo Rate of formation=change in product/change in timeo Rate of consumption=-change in reactant/change in time- Rule for any reactiono aA+bBcC+dD- The reaction rate is given byo Rate=-1/a x change in [A]/change in time=-1/b x change in [B]/change in time=1/c x change in [C]/change in time=1/d x change in [D]/change in timeo This type of expression is known as relative reaction rate as it is the rate derived from the reaction stoichiometry- A straight line is defined by y=mx+c where y=y variable (dependent), x=x variable (independent), c=constant (y-intercept) and m=gradient (slope)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Gradient the slope of a straight lineo M=change in y/change in x, rise/runo A positive gradient (or slope) has m>0o A negative gradient (or slope) has m<0 o A horizontal line has m=0 (constant function)o A vertical line is parallel to the y axis and has infinite slop (undef)- Tangent a straight line that touches a curve at a single point without intersecting it- Draw a straight line at the point of interest, keeping the angle between the tangent and the curve the same on both sides- Instantaneous rate the rate of a reaction at a specific instant during the course of a reaction- The instantaneous rate is obtained from the straight-line tangent that touches the curve of concentration as a function of the time at the point of interest- The initial rate is the instantaneous rate determined for
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