k & K

Moderators: Chem_Mod, Chem_Admin

Diana Sandoval 1K
Posts: 61
Joined: Fri Sep 28, 2018 12:25 am
Been upvoted: 1 time

k & K

Postby Diana Sandoval 1K » Fri Mar 08, 2019 8:30 am

What is the difference between k in kinetics and K in equilibrium/ thermo?

Ray Huang 1G
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: k & K

Postby Ray Huang 1G » Fri Mar 08, 2019 8:51 am

k in electro should be Boltzmann's constant while k in kinetics is a number unique to each reaction scaling how quickly the reaction proceeds.

Anushi Patel 1J
Posts: 61
Joined: Fri Sep 28, 2018 12:19 am
Been upvoted: 1 time

Re: k & K

Postby Anushi Patel 1J » Fri Mar 08, 2019 10:00 am

To add to the previous answer, K in thermodynamics is the equilibrium constant, which describes the concentrations of reactants and products at equilibrium, and doesn’t have anything to do with the speed of the reaction.

Nico Edgar 4L
Posts: 32
Joined: Fri Sep 28, 2018 12:19 am

Re: k & K

Postby Nico Edgar 4L » Fri Mar 08, 2019 11:14 am

k is a rate constant dependent on the reaction you have. K is the equilibrium constant.

Jennifer Lathrop 1F
Posts: 71
Joined: Sat Dec 02, 2017 3:00 am

Re: k & K

Postby Jennifer Lathrop 1F » Fri Mar 08, 2019 12:34 pm

how do you know when to use it as a Boltzmann's constant or a rate constant?

Jennifer Lathrop 1F
Posts: 71
Joined: Sat Dec 02, 2017 3:00 am

Re: k & K

Postby Jennifer Lathrop 1F » Fri Mar 08, 2019 12:34 pm

or are those the same?

Gracie Ge 2E
Posts: 28
Joined: Wed Nov 21, 2018 12:19 am

Re: k & K

Postby Gracie Ge 2E » Sat Mar 09, 2019 5:26 pm

isn't boltzmann's constant used to calculate entropy with the number of possible states of a molecule and the number of molecules?
rate constants and boltzmann are entirely different things.

Amy Dinh 1A
Posts: 62
Joined: Fri Sep 28, 2018 12:23 am

Re: k & K

Postby Amy Dinh 1A » Sat Mar 09, 2019 11:27 pm

k is Boltzmann constant, which is equal to 1.38064852 × 10^-23 m2 kg s^-2 K^-1. K is the equilibrium constant of a reaction, which is calculated by the concentration of the products over concentration of the reactants.

Lumbini Chandrasekera 1B
Posts: 63
Joined: Fri Sep 28, 2018 12:18 am

Re: k & K

Postby Lumbini Chandrasekera 1B » Sat Mar 09, 2019 11:38 pm

k is the Boltzmann rate constant while K is the equilibrium constant for a certain reaction.

maldonadojs
Posts: 57
Joined: Fri Sep 28, 2018 12:27 am

Re: k & K

Postby maldonadojs » Sat Mar 09, 2019 11:48 pm

I am sure the question will tell us to use the k as a rate constant in kinetics in the question, whereas the k Boltzmann constant will be used to calculate the entropy. K will be given in an acids and base question. It is based off of context.

Krista Mercado 1B
Posts: 60
Joined: Fri Sep 28, 2018 12:26 am

Re: k & K

Postby Krista Mercado 1B » Sun Mar 10, 2019 12:44 pm

The difference is that k is Boltzmann's constant, while K is the equilibrium constant for a given reaction.

Aarti K Jain 1L
Posts: 30
Joined: Fri Sep 28, 2018 12:20 am

Re: k & K

Postby Aarti K Jain 1L » Sun Mar 10, 2019 1:16 pm

In kinetics, k is the rate constant, whereas K is the equilibrium constant. Also, K = k/k', which means the the equilibrium constant is equal to the ratio of rate constants of the forward (k) and the reverse (k') elementary reactions.

allisoncarr1i
Posts: 60
Joined: Fri Sep 28, 2018 12:15 am

Re: k & K

Postby allisoncarr1i » Wed Mar 13, 2019 10:16 am

lower case k is the boltzmann constant and upper case K is the equilibrium constant

Kyither Min 2K
Posts: 60
Joined: Wed Oct 03, 2018 12:15 am

Re: k & K

Postby Kyither Min 2K » Wed Mar 13, 2019 2:35 pm

k is the rate constant so it's basically an indicator of how fast the reaction will happen. K is the equilibrium constant that tells you the ratio of products to reactant concentrations when the reaction is at equilibrium. Based on the relationship between k and K, we can determine that the forward reaction's rate constant, k will be larger than the reverse reaction rate constant if K (equilibrium constant) is larger than 1.

Megan_Ervin_1F
Posts: 78
Joined: Fri Sep 28, 2018 12:18 am

Re: k & K

Postby Megan_Ervin_1F » Wed Mar 13, 2019 8:42 pm

It is also important to note that K can be figured out by taking the ratio of the forward reaction K to the reverse reaction K

Melissa Villanueva1K
Posts: 64
Joined: Wed Nov 15, 2017 3:01 am

Re: k & K

Postby Melissa Villanueva1K » Fri Mar 15, 2019 10:33 pm

Will there be a clear indication of 'k' and 'K' on the final? Such as bolding one over the other. Thanks.

Ashley P 4I
Posts: 64
Joined: Wed Nov 15, 2017 3:04 am

Re: k & K

Postby Ashley P 4I » Sat Mar 16, 2019 12:32 pm

Melissa Villanueva1K wrote:Will there be a clear indication of 'k' and 'K' on the final? Such as bolding one over the other. Thanks.

Do you mean on the constants and equations sheet?

Milena Aragon 2B
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

Re: k & K

Postby Milena Aragon 2B » Sat Mar 16, 2019 2:02 pm

Melissa Villanueva1K wrote:Will there be a clear indication of 'k' and 'K' on the final? Such as bolding one over the other. Thanks.


I think in order to avoid confusion, it may be written out for us along with the variable e.g. "the rate constant, k,..."

JacobHershenhouse3G
Posts: 32
Joined: Thu Jan 10, 2019 12:17 am

Re: k & K

Postby JacobHershenhouse3G » Sat Mar 16, 2019 2:23 pm

K is the equilibrium constant and kr is the rate constant, symbolizing different constant values with different meanings, applied in different equations but they are related. K is equal to the overall forward rate constant over the reverse rate constant because at equilibrium the forward and reverse rates (not the constants) are equal.


Return to “Kinetics vs. Thermodynamics Controlling a Reaction”

Who is online

Users browsing this forum: No registered users and 2 guests