Sapling #6 (Week 9/10)

[Jessica Luong 3K]

I'm having trouble understanding the concept to solve this question. Can someone simplify an explanation for me?

[Amanda Bueno-Kling]

For this question, first we can group the graphs by zero order or first order.
For a zero‑order reaction, the rate is constant and it does not change based on concentration of reactant. This will look like a straight line, so group the two straight lines together as zero order reactions.
rate=k[X]^0=k
For a first order reaction, the rate is not constant and changes based on concentration of reactant, so it will not be a straight line. Group the two curved lines as first order reactions.
Then, we want to choose which of them in each pair show [X] versus t, and which of them show [Y] vs t.
Since X is the reactant, it should show graphs that start with a lot of X and then decrease over time. In other words, the slope should be negative.
Since Y is the product, it should show graphs that start with very little Y and increase over time. The slope should be positive.

[Nico Medina]

I was wondering this too, thanks for the help!

[Nan_Guan_1L]

first of all, [X] vs t should be shown as a line with negative slope in both cases since reactants decrease in concentration; [Y] vs t should be shown as a line with a positive slope since products accumulate in the process.


for first or second order reactions, rate=k[X] or rate=k[X]^2. which means that as X concentration decreases during the reaction, the rate is also decreasing. The change in concentration of X would be different every time interval, resulting in a curved plot.

for zero-order reactions, rate=k and thus the rate is constant and independent of concentration.