Thread: How do you calculate the rate constant from a graph that has a zero order?

A zero order rate constant is a zero order rate constant. You can't fit it into a first order equation because the reaction proceeds differently with time, and moreover, the UNITS of the constants are not the same. If the reaction is truly zero order, the rate constant will be the slope of the line, and be in terms of moles reacted per unit time. Thus, you can determine the time frame of the reaction if you want to carry it out to be compatible with your timing equipment.

I would like to know how do you calculate the rate constant from a graph that yields a zero order. The graph is linear of course to have a zero order. I need to calculate the rate constant from a graph Concentration vs. Time data. I do not know which number to choose to place in the first order equation. Would I be able to choice the inital concentration and the inital time to find the constant? Please help if possible.

baby beyonce,

The equation of a zeroth order reaction is [A] = kt (where A is either a reactant or product in the reaction). Therefore, when a graph of [A] vs. t is plotted, the result will be a straight line going through the origin with a slope of k. That means you simply need to pick two data points on your graph (ANY two points will do), use them to compute the slope, and that is your rate constant.

(Note: Whether the line is sloping up or down depends on whether you are plotting the concentration of a reactant or product. If the slope is positive, the slope equals k. If the slope is negative, the slope equals -k.)