## Zero Order

$\frac{d[R]}{dt}=-k; [R]=-kt + [R]_{0}; t_{\frac{1}{2}}=\frac{[R]_{0}}{2k}$

haileyramsey-1c
Posts: 105
Joined: Thu Jul 25, 2019 12:18 am

### Zero Order

When is a reaction zero order or how do we determine that it is?

Brian Tangsombatvisit 1C
Posts: 119
Joined: Sat Aug 17, 2019 12:15 am

### Re: Zero Order

A reaction is zero order when the rate of reaction is independent of the concentration of R, often when the catalyst and enzyme are saturated and increasing the concentration of R does not increase the rate. The rate is limited by k only. It can be determined by looking at experimental data. For example, looking at all of your reactants (say, 3), if the concentration of 2 are held constant, while the 3rd is doubled, and the rates of the two trials are the same, then you know that the order of the 3rd reactant is zero since changing its concentration has no effect on the rate of the reactant. If the other two reactants are also zero order, then the overall reaction is zero order since you would total the reactants' orders.

ALegala_2I
Posts: 102
Joined: Thu Jul 11, 2019 12:17 am

### Re: Zero Order

Are zero order reactions common?

John Liang 2I
Posts: 102
Joined: Fri Aug 30, 2019 12:18 am

### Re: Zero Order

Zero-order reactions are solely k based. the rate=k[A]^0 which makes [A]=1 and therefore rate=k. you can tell if this happens when a graph showing concentration over time is a flat line since this usually happens when an enzyme/catalyst is saturated and the rate is constant. hope this helps

Sara Richmond 2K
Posts: 110
Joined: Fri Aug 30, 2019 12:16 am

### Re: Zero Order

As far as I can tell zero order reactions are not that common, but they proceed when the rate of the reaction is independent of the concentration of the substances.

Caroline Zepecki
Posts: 101
Joined: Fri Aug 09, 2019 12:16 am

### Re: Zero Order

Zero order reactions depend only on K, because [A]^0 =1, so it doesn't effect the rate.

Emily Vainberg 1D
Posts: 102
Joined: Sat Jul 20, 2019 12:15 am

### Re: Zero Order

You figure out a reaction is zeroth order the same way you figure out reactions are first or second order. Compare the concentrations given with the changes in initial rate. Rate=k[A]^0 which makes [A]=1 and therefore rate=k.

805394719
Posts: 104
Joined: Wed Sep 11, 2019 12:16 am

### Re: Zero Order

A zeroth-order reaction has a rate that does not depend on the concentration of any of the reactants but takes place at the same rate no matter the concentration of the reactant. For example, the reaction takes place at the same rate when reactant A's concentration is 1/2 of its initial concentration or 1/4 of its initial concentration or 1/8 of its initial concentration. You can identify a zeroth-order reaction by the graph of the concentration of the reactant against time which gives a straight line with a negative slope which gives the rate of the reaction. The plot of the rate against time is constant with a straight line and a slope of zero.

Jessa Maheras 4F
Posts: 121
Joined: Fri Aug 02, 2019 12:16 am

### Re: Zero Order

ALegala_2I wrote:Are zero order reactions common?

Yes I think they are less common than 1st order but definitely more common than third. That’s a good q for dr. Lavelle!