Difference between first and second order


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aphung1E
Posts: 101
Joined: Sat Aug 24, 2019 12:15 am

Difference between first and second order

Postby aphung1E » Mon Mar 09, 2020 1:49 pm

I'm still not understanding this concept. Can someone explain the concept of the difference between a first order reaction and a second order reaction?

Alfred Barrion 2H
Posts: 100
Joined: Sat Jul 20, 2019 12:16 am

Re: Difference between first and second order

Postby Alfred Barrion 2H » Mon Mar 09, 2020 1:52 pm

A first order reaction depends on the concentration of one of the reactants. A second order reaction is the square of the concentration of a single reactant.

Amy Pham 1D
Posts: 103
Joined: Fri Aug 09, 2019 12:15 am

Re: Difference between first and second order

Postby Amy Pham 1D » Mon Mar 09, 2020 1:55 pm

In a first order reaction, the reaction rate depends on the concentration of a single reactant. In a second order reaction, the reaction rate depends on either the concentration of two different reactants raised to the first power, or the concentration of a single reactant raised to the second power. When the reactants are doubled in a first order reaction, the rate of reaction doubles, while if you double the reactants in a second order reaction, the reaction rate will quadruple.

005324438
Posts: 51
Joined: Sat Aug 24, 2019 12:16 am

Re: Difference between first and second order

Postby 005324438 » Fri Mar 13, 2020 10:22 am

There are many ways a reaction can become first or second order, but the main difference is how many reactants the rate depends upon. If the rate depends on one reactant, then it is first order. If the rate doesn't depend on a reactant (say it depends on a catalyst instead) then the reaction is zeroith order. If the rate depends on two reactants, then it is second order and so on. Another way a reaction can be second order is if it uses two moles of the same reactant, and that reactant changes the rate. This is where we get [a]^2 in our rate law, and is another way a reaction can be second order.

805307623
Posts: 99
Joined: Fri Aug 09, 2019 12:17 am

Re: Difference between first and second order

Postby 805307623 » Fri Mar 13, 2020 10:38 am

In a 1st order reaction, there is one reactant in the rate law. In a 2nd order reaction, there's either a rate law with one reactant to the second order, or two reactants to the first order.

Pablo 1K
Posts: 118
Joined: Sat Feb 02, 2019 12:15 am

Re: Difference between first and second order

Postby Pablo 1K » Fri Mar 13, 2020 10:46 am

Think about it from a mathematical view, a first order means it is dependent on one reactant to the first power. A second order means either a) dependent on two reactants to the first power or one reactant to the second power, in order for reaction to proceed.

Asha Agarwal 1E
Posts: 51
Joined: Fri Aug 30, 2019 12:16 am

Re: Difference between first and second order

Postby Asha Agarwal 1E » Fri Mar 13, 2020 10:53 am

The rate of a first order reaction depends only on the concentration of one reactant. However, the rate of a second order reaction depends on the concentration of two reactants to the first power or one reactant to the 2nd power.


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