PH and POH

[IA_1D]

Hi,
Is there a difference between Ka and Kb when calculating the end result of a Ph and Poh?

[Nicola Higgins 14B]

Yes, I believe so, because Ka x Kb = 1.0 x 10^-14. This means that they will not always be equal to eachother.

[Clayton Dinh 3C]

Ka directly correlates to pH while Kb correlates with pOH.

[Angela Harrington 2L]

Yes, there is a difference because depending on whether you use Ka or Kb will affect what answer you get when you take the -log(x) after making the ICE table. If you use Ka, then the -log(x) will give you the pH, but if you use Kb, then the -log(x) will give you the pOH and you'll have to subtract that value from 14 to get the pH. Ka x Kb = Kw and you can use this to switch back and forth between Ka and Kb because Kw is a constant at 1.0 x 10^-14, depending on what you are trying to solve for.

[Samir Panwar]

Yes, there is a difference being that when you are given the Ka you can find the pH , whereas given the Kb you can find the pOH.

[Sophie Vikram 1L]

Yes, there is a difference between Ka and Kb. Because Kw is the product of Ka and Kb, the two will usually be in different proportions. You cannot use Kb to to find the pH you must use Ka and vice versa.

[Albert 1I]

Ka and Kb are inversely proportional, using the Ka value of an acid would give you the pH. Using the Kb value of a base would give you the pOH.

[Emaad Sohail 3F]

pH + pOH = 14, and through the same relation Ka*Kb=1.0 * 10^-14. However, you can't use Ka to calculate pOH directly, or use Kb to calculate pH directly.

[005778617]

Hi,

Similar to what everyone has said, you should remember that:
(1) pH + pOH = 14
(2) Ka * Kb = Kw

The pH value is correlated to the Ka value in the sense that pH = -log[Ka]. As for the pOH value, it is correlated to the Kb value with pOH = -log [Kb]. These two values are inversely proportional.

[sophiavmr]

Yes, if the Ka is the equilibrium constant value for the forward reaction (deprotonation) then the Kb will be the equilibrium constant for the reverse reaction (conjugate base gaining a proton)

[Aparna Pillai 1E]

Hi! Yes, Ka and Kb are different and need to be distinguished for the purposes of solving for either pH or pOH. The relationship between the two is as follows:
Ka x Kb = Kw (which, at 25 degrees C, is equivalent to 10^-14)
Ka corresponds to pH, as it generally has the concentration for H3O+ in its equation. Likewise, Kb corresponds to pOH, as it has [OH-] in its equation.

[505739628]

If you are using Ka in your calculations it will give you the pH when you take the negative log, but when you use Kb it will give you the pOH. So if you need the pH when given the Kb you would just do all of your normal calculations and then, after taking the negative log of the concentration of OH-, you would subtract that from 14 to get the pH. Hope this helps!

[Alice Weber 3I]

Yes there is. When you are given a Ka, the x you find can be used to find the pH. The same goes for Kb and pOH.

[kayleec1004]

Ka * Kb = Kw (1.0*10^14)
When you use Ka, the -log(x) will give you the pH.
When you use Kb, the -log(x) will give you the pOH. You have to subtract that value from 14 to get the pH.

[505749458]

Yes, Ka is the equilibrium value of the weak acid and Kb is the equilibrium of the weak base, which multiply to 10^-14.

[tashyavakil 2K]

With Ka you can find pH and with Kb you can find pOH

[trucle_2I]

Yes, the difference is that Ka is used to calculate pH and Kb is used to calculate pOH.

[Josh Richter 2C]

In general, you want to use pH with KA, pKA, and acids, and you want to use pOH for KB, pKB, and bases. However, if the problem gives pH and you need pOH, or if the problem gives KA and you need the KB of the conjugate base, you can easily convert between them.

[Connor_Olsen_2K]

Yes, Kb refers to base and will result in a pOH when doing log calculations. Ka refers to acids and will yield pH when doing log calcs.

[Natalie Flores 1F]

Hi! From what I understand, Ka can be used to solve for pH and Kb can be used to solve for pOH. However, Ka*Kb = Kw (Kw=1.0x10^-14) so if you want to solve for either Ka or Kb (given that you know at least one) you can. Also, when solving for pH, use the Ka value and when solving for pOH, use the Kb value, and remember pH+pOH = 14 so you can also solve for either pH or pOH given that you know at least one. Hope this helps!

[Furkan Acar 3C]

Ka is to PH while Kb is to POH. Or at least I think it is?

[Isabella Perez Dis3L]

Hi! When using the Ka value of an acid, we can find the PH. When using the Kb value of a base we could find the pOH. (Ka correlates to PH and Kb correlates to pOH)

[Baffour Adusei 1L]

Hi! The Ka value allows you to find the H₃O⁺ concentration and pH.
The Kb value allows you to find the OH^- concentration and pOH.

[Samantha Toscano 2C]

Yes! Ka is for the pH and Kb would be for pOH

[Polo Morales 3C]

Yes, Ka is the equilibrium constant for a reaction that deals with increase in [H3O+] ions, and therefore helps you determine pH. Kb is the equilibrium constant for a reaction that increases concentration of [OH-], and can thus help you find pOH. Hope this helps!

[Abigail Tran 14a]

Yes, there is a difference because when you use Ka, -logx will give you pH, but when you use Kb, -logx will give you pOH and pH and pOH will add up tog get 14. ka x Kb= 1x 10^-14

[Veronica Larson- 1I]

Yes, there is a difference because Ka x Kb = 1.0 x 10^-14. Using Ka will give you a pH value, and using Kb will give you a pOH value.

[jaycmartinezDisc3b]

Yes, there is a difference between Ka and Kb when you calculate pH and pOH. Ka and Kb have an inverse relationship, which both represent the dissociation of the given acid/base. If you were to use the Ka on a problem with a base, it would be wrong as the Ka represents the protons in the solution and not the hydroxide. Thus you'll need to identify and convert to the appropriate dissociation constant using ka x kb= 1.0x10^-14.

[205484435]

There is a difference: with Ka you can find the pH and with Kb you can find the pOH

[Jordyn Lee 1J]

Hi, there is a difference between Ka and Kb because when you find the pH, it can help you find the Ka of a reaction and vice versa with pOH and Kb.

[Matthew Vu 3C]

You should use Ka for pH and Kb for pOH. Using for Kb to find pH will first require you to find the pOH, and then you will have to do 14-pOH to find the pH

[Hannah Carsey 1B]

Yes, there is a difference in that when you are given Ka, calculating -log[X] will give you the pH and when given Kb, calculating -log[X] will give you the pOH. Two applicable equations: pH + pOH = 14 and Ka * Kb = 1.0x10^-14.

[Caitlyn Lo 2F]

Yes there is a difference in Ka and Kb values because Ka coincides with acids and Kb coincides with bases. Then we get Ka x Kb = Kw (1.0 x 10^-14)

[andreagutierrez 3K]

Yea Ka determines ph and Kb gives pOH

[Holly Do 2J]

The Ka is basically the acid equilibrium (hence the a for acid) while the Kb is for the base (hence the b for base). So when you are given a Kb and are asked to solve for pH remember that you are going to have to calculate the pH through the pOH.

[ThomasL1L]

Ka translates to pH as it is based off H3O+ while Kb translates to pOH as it is based off OH-.

[Erin Chin 1L]

Ka and Kb are both equilibrium constants, but Ka is used when dealing with acids while Kb is used when dealing with bases. With Ka, you can find pH and with Kb, you can find the pOH value.

[Natalie Coughlin 1I]

Ka refers to an equilibrium constant that can be used for an acid, which therefore gives you your pH value. Kb refers to the an equilibrium constant that is used for a base, which then therefore gives you your pOH.

[Nyah Zhang 1E]

Yes, there is a difference. When given Ka you can solve for pH. When given Kb, you can use it to get pOH.

[Natalie Quilala 1I]

Ka is equal to Kw/Kb. Kb is equal to Kw/Ka. Kw is equal to 1*10^-14. This means that Ka and Kb most likely won't be equal, and the pH and pOH aren't equal either.

[Lindsey Walter 3E]

Yes, Ka is directly related to pH while Kb is directly related to pOH. This is because Ka is for acids, and pH is based on the concentration of H+ ions while Kb is for bases and pOH is based on the concentration of OH- ions.

[riddhiparikh]

When you are given Ka, then you solve for pH. When you are given Kb, then you solve for pOH. Ka is equal to Kw/Kb. Kb is equal to Kw/Ka. Kw is equal to 1*10^-14.

[105784203]

Hi,
Is there a difference between Ka and Kb when calculating the end result of a Ph and Poh?

yes there is

[Mekenna Faulkner]

Ka correlates with ph while on correlated with poh. When taking the log of your solved value from the ice table, which k you have determines what you’re solving for. If it’s kb then taking the log will give you poh. Taking the log of a ka value gives ph.

[Chiara Frank]

Hi! Yes, if you have the reaction for an acid, you will want to use the Ka value, as this is the acidic equilibrium constant. If you have a reaction for an acid, you can use the Ka value to calculate the concentration of H3O+, which you can then take to calculate the pH and then subtract from 14 to find the pOH. However, if you have an acid and are given the Kb, you would want to use the formula Ka x Kb = 1.0 x 10^-14 to solve for Ka. If you have a base you would act similarly, just with Kb to initially solve for pOH. I hope this was helpful!

[Ellen Brock 2I]

Yes. Best way to think about it is k acid and k base. Which indicates that ka is for acids and used for pH while kb is for bases and used for pOH. Hope this helps!

[Kendall Brown]

It will depend on the reaction, for whether you use Ka or Kb. If H+ os being formed use Ka.

[Palig Kechichian 3F]

Ka is for acids while Kb is for bases.
pH is calculated with the concentration of hydronium, which we use to calculate the acidity of a solution, and pOH is calculated with the concentration of hydroxide, which we use to observe the basicity of a solution.

[Sarthika Chimmula 3H]

Ka is used for weak acids while Kb is used as the equilibrium constant for weak bases. Because weak acids get dissociated into H3O+ ions, you can directly calculate the concentration of H3O+ using an ICE table, while you can directly calculate the concentration of OH- ions from the equilibrium dissociation of a weak base. From here, you can just use the fact that [OH-][H3O+] = 10^-14 and pH + pOH = 14 equations to get the concentration/value that you do not have.