The APsolute RecAP: Chemistry Edition - Episode 56: Concentration Changes Over Time
Description
An AP Chemistry classic experiment for concentration changes over time is determining the rate law of fading Crystal Violet. (1:07 ) If the reaction is zero order, the plot of our concentration of our reactant vs time is linear. (2:51 ) If the reaction is first order with respect to our crystal violet, a plot of the natural log of the concentration of the reactant vs time will be linear. (3:17 ) If the reaction is second order with respect to crystal violet, a plot of 1 over concentration vs time will be linear. (3:45 ) We can use the graph and determine k as follows: for zeroth and first order k equals - slope and for second order reactions k = slope. (5:03 ) Integrated rate laws can be used to calculate the concentration after a specific amount of time or to determine how long a reaction has to run to get a specific concentration. A specific application of the rate laws is half-life. In AP Chemistry, half-life is always a first-order reaction. (6:15 )
Question: If you have a reaction with a half-life of 4 days and an initial concentration of 0.1M, what fraction will be left after 20 days? (8:30 )
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