Acids and Bases

[Arya Bhalla 1H]

Is there a section for Acids and Bases on the 14B Chemistry Community section?

[Chem_Mod]

Since we have an Acid and Base section in Chem 14A and in Chem 14B I thought it best to keep it as one section listed under Chem 14A.

You can find the Chem 14B Acid and Base topics here: viewforum.php?f=52

[Giacomo Carter 2D]

There are not videos but there are textbook readings and questions you can do.

[Emily Lam 2H]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

[Maya_Panozzo_2D]

Lavalle sent an email out recently saying that it will be provided to us and gave a list.

[Maya_Panozzo_2D]

In the equation where it says that pKw = pH + pOH = 14 at 25(degrees c) what does the p mean in the pKw section? And just to clarify the Kw refers to the equilibrium constant when water is involved right?

[Madeline Redmond 2A]

Yes, Kw is the equilibrium constant for pure water. The term pKw comes from the equation pKw=-logKw, which is the same way you would calculate pH or pOH, and because the value of Kw at 25 deg C is 1.0x10^-14, when you input it into this equation you get 14 as the pKw value. Therefore the equation pKw=pH+pOH can be simplified to 14=pH+pOH.

[bella moore]

The p in pH represents the log function. For instance, if you are finding pOH of a solution, you are taking the log of the concentration of OH. You can use this to find the pH (which is short for pH30+) by subtracting the pOH from 14. Also, I think that the w in Kw refers to water.

[Bella Valente 2K]

Yes, Kw is the equilibrium constant for water and is equal to 14.

[Phoebe 1H]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

[Phoebe 1H]

Also, what does amphiprotic mean?

[Ayesha Ashraf]

For a solution to be alkaline it must have a pH greater than 7 so it contains more OH- ions than H3O+ ions. It is a chemical that dissolves in water and combines with acid to form salts thus making acids less acidic. An example is NaOH.

[Sarah Wu 2B]

Something is amphiprotic if it is both a proton donor and acceptor.

If a problem includes a weak acid or weak base, you typically will need to set up an ICE table to determine the concentration of hydronium or OH ions at equilibrium, and the concentration of the weak acid or base at equilibrium (since it doesn't fully dissociate). You can then use these values to determine Ka or Kb using the equilibrium constant expression.

[Deivy Gonzalez 3H]

Le Chatelier's Principle basically determines the -x and x within the I.C.E formula?

[Amber2E]

How do you solve for the new concentration of products and reactants if you add products to the system? Do you find 1/K and flip the equation so the products are the reactants?

[Jake1K]

This is a response to what amphotheric means. An amphotheric compound is one that can receive or give a proton. It can act as both and acid and a base. For example, water.

[Jake1K]

What is an acid and a Base? How can you tell the difference? Have a nice day.

[805737147]

What is an acid and a Base? How can you tell the difference? Have a nice day.

An acid is a proton donor and a base is a proton acceptor. For example, NaCl would disassociate into Na+ and Cl-. H20 can disassociate into OH- and H+. The Na+ combines with the OH- to form NaOH and HCl forms.

[805737147]

Le Chatelier's Principle basically determines the -x and x within the I.C.E formula?

The value of 'x' in the ICE formula comes from the molar concentrations in the chemical equation. For example in 5NaCl + 2H0, the respective 'x' would be -5x and -2x for the reactants. Le Chatelier's Principle refers to the system trying to minimize the change when something is changed at equilibrium. (This refers to in class when we were talking about how would the system respond if we added more products or if we removed a reactant).

[Abby Freeman 1C]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

[Zain Syed 1E]

What is an acid and a Base? How can you tell the difference? Have a nice day.

An acid is anything the donates an H+(proton) but a base is anything that accepts an H+(proton). A lot of the acids have an H in front of them which helps distinguish from a base.

[Suraj Kulkarni 2B]

Also, what does amphiprotic mean?

Hey! So if something is amphiprotic it means it can essentially act as either an acid or base (note that the word has "protic" which refers to proton in it). I used to confuse this with amphoteric, which refers to being able to react with either an acid or base.

[Suraj Kulkarni 2B]

Le Chatelier's Principle basically determines the -x and x within the I.C.E formula?

Essentially! Basically, the coefficient next to the value of x refers to the number of moles present of that substance in the balanced chemical reaction. We would use -x if that substance is being used up and converted into something else (ie: reactants to products or products to reactants, etc...).

[Aanchal Kasargod 1H]

I just had a quick question about conjugate acids and bases. I just wanted to know how we know which compound is the conjugate acid/base in the chemical reaction and also how this concept may come up when solving problems?

[Aanchal Kasargod 1H]

Another question I had was about something Professor Lavelle mentioned at the end of today's lecture. He was explaining how when we get an acid that causes the pH to go over 7, we must remember that without an acid, neutral water itself has a pH of 7 so there is something we must take into account regarding that. I didn't quite understand that, so I was hoping someone who did could help? Thanks!

[Bella Valente 2K]

If a temperature is not given, can we assume we are solving at 25 degrees celcius?

[505769291]

I just had a quick question about conjugate acids and bases. I just wanted to know how we know which compound is the conjugate acid/base in the chemical reaction and also how this concept may come up when solving problems?

When a base accepts a proton it becomes a conjugate acid and when an acid donates a proton it becomes a conjugate base. So you can look at a reaction and see if a proton was gained or lost to determine if its a conjugate acid or base.

[505769291]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

The conjugate seesaw refers to the fact that the stronger the acid is, the weaker its conjugate base will be. Also, the stronger the base the weaker its conjugate acid will be.

[505769291]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

If you are dealing with a weak acid or base and therefore cannot assume it completely dissociates, you have to calculate the ion concentration after the reaction has taken place by constructing an ice table to determine equilibrium concentrations. You will then set the K value given equal to the equilibrium concentration of products over reactants. By solving for x you will be able to calculate the ion concentration.

[Ambar Zamuria 1E]

Also, what does amphiprotic mean?

Amphiprotic means to be able to donate and accept protons. Then there is amphoteric which means the ability to react to acids and bases. In some cases, they can be both, but they are two different classifications that one can mistake for the other.

[Angie Tan 2L]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

A conjugate seesaw is the concept that the stronger the acid, the weaker its conjugate base. The stronger the base, the weaker its conjugate acid. This leads us to the formula pKa * pKb = pKw = 10^-14. pKa and pKb are inversely proportional since their product is a constant; if one number is higher, the other number has to be lower to get the same product. As a result a high pKa (weak acid), means a low pKb (stronger weak base) and vice versa.

[Marina Nimnual]

How do you solve for the new concentration of products and reactants if you add products to the system? Do you find 1/K and flip the equation so the products are the reactants?

In order to solve for the new concentration when more product is added to the system, you would start off with the initial conditions for the reactants as their concentrations at equilibrium, and the initial conditions for the products as the total amount of concentration of it in the system. Then, instead of subtracting from the reactants and adding to the products, it would be vice versa. You would add to the reactants (ex: +x) and subtract from the products (ex: -2x). You would equal the [products]/[reactants] to the equilibrium constant and calculate for x.

[clarissa_ram 2L]

If a temperature is not given, can we assume we are solving at 25 degrees celcius?

I believe so! I asked my TA the same question while doing practice problems and he said to assume it is at 25 degrees celsius :)

[clarissa_ram 2L]

So when we have strong acids/bases, we infer that their concentration is the same for O3H+ / OH-. For example if a problem says we have 0.0020M of HCl, would the concentration of H3O+ also be 0.0020M? And would the rationale behind it be that the strong acid fully dissociates into H3O+ therefore the concentration is the same?

[Vivek Punn 1E]

I just had a quick question about conjugate acids and bases. I just wanted to know how we know which compound is the conjugate acid/base in the chemical reaction and also how this concept may come up when solving problems?

Well it depends on the chemical reaction that you are observing. Generally however, observing a molecule that donates a hydrogen is considered to be an acid so the conjugate base would be the molecule that then accepts the hydrogen. The opposite is also true of the conjugate acid. Another thing that is important to know about the conjugate acids and bases is that having a strong acid means that the conjugate base will be weak and vice versa. Hopefully that helps.

[505780104]

After learning about weak acids and bases during lecture, I was confused about the last message Professor left us with to wrap up the topic. How does autoprotolysis generate 10^-7 mol L^-1 H3O+, and how is a solution considered neutral if the concentration of H3O+ is less than 10^-7? If someone understands this concept, please help! Thank you.

[505780104]

Quick question on the proton deprotonation and protonation value. When given the percentage, what are the necessary steps to take in order to find out the pH of the solution? I understand that is a fraction consisting of a denominator that reflects the molarity of the solution, however, what is the numerator? Do I Just solve for the numerator by setting the fraction equal to the percentage deprotonation? Then, the value calculated as the amount deprotonated is placed into the pH equation,-log(*value calculated as the amount deprotonated). Are there any other steps? I am mostly confused about how to solve for the numerator- which is necessary for the pH equation. Thank you for your help and input! Sorry if any part of it was confusing to understand !

[Bella Valente 2K]

What is the conjugate seesaw exactly?

The conjugate seesaw is the idea that the stronger the acid, the weaker its conjugate base, and that the stronger the base the weaker its conjugate acid.

[405735471]

Where do we find the answers to the recommended practice questions from the book?

[Christian Huang 1G]

Just a quick question:
Is there a way to determine whether something is weak or strong besides knowing how much something might dissociate? Would we have to memorize acids and bases that are weak and strong?

[Titania Le [2F]]

Just a quick question:
Is there a way to determine whether something is weak or strong besides knowing how much something might dissociate? Would we have to memorize acids and bases that are weak and strong?

Professor mentioned during lecture that if an acid has a small Ka value (anything less than 10^-3), it is a weak acid. I do not remember specifically what he mentioned for weak bases but my CHEM 14A professor simply said you have to memorize the list of strong/weak acids/bases.

[D Garcia 1C]

Also, what does amphiprotic mean?

When something is amphiprotic that means it can serve as both an acid or base.

[D Garcia 1C]

Where do we find the answers to the recommended practice questions from the book?

If you open up the class on Canvas there should be a link titled "Chemical Principles, 7th Edition, Student Solutions Manual (Fundamentals, 1-7, 9)." Those are where you can find the answers. :)

[Ella Figueroa 2H]

Just a quick question:
Is there a way to determine whether something is weak or strong besides knowing how much something might dissociate? Would we have to memorize acids and bases that are weak and strong?

Yes my TA told us in the discussion that weak and strong acids/bases simply need to be memorized. There are 6 main strong acids and 6 main strong bases. Even if Professor Lavelle does not require them to be memorized for this class, most professors will so it is worthwhile to simply learn them now.

[Ella Figueroa 2H]

After learning about weak acids and bases during lecture, I was confused about the last message Professor left us with to wrap up the topic. How does autoprotolysis generate 10^-7 mol L^-1 H3O+, and how is a solution considered neutral if the concentration of H3O+ is less than 10^-7? If someone understands this concept, please help! Thank you.

Hi! So I'm not sure about your first question, but in regards to neutrality, I'll do my best to explain. Water at a neutral pH is equal to the concentration of H3O+ = 10^-7, When you are finding the concentration of an acid that has already dissociated in water, the value of the dissociated acid is too small to matter. When it mixes with the solvent (water), nothing changes and the concentration of H30+ remains the same.

[Isabelle Kim 3E]

What is an acid and a Base? How can you tell the difference? Have a nice day.

An acid, in Bronsted-Lowry's definition, is that it is a molecule that can donate a proton (H+) to a neighboring molecule
A Bronsted base is a molecule that accepts a proton (H+)
You can recognize these by observing the proton transfer between the two molecules.

[Isabelle Kim 3E]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

When dealing with weak acids/bases, we would be given the Ka/Kb values to solve for the pH or pOH (whatever it is). You'd also want to create an ICE table to calculate the concentration of hydronium or hydroxide ions. Again, it really depends on what you're trying to get.

[805737147]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

The conjugate seesaw is the idea that a very strong acid has a very weak conjugate base and a very strong base has a very weak conjugate acid. I know that the strength can tell us information about pKa (for example a strong acid has a lower pKa), but maybe someone else can help explain the relevance in a reaction!

[805737147]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

In this case - with a weak acid or base - we have to construct an ICE table, place in the initial concentration amounts, and then solve for x. From there, we can use x to find the pH or pOH.

[705801855]

Yes, there is a section for acids and bases.

[505681302]

Is there a section for Acids and Bases on the 14B Chemistry Community section?

Yes there is you can find it on the class website in a direct link :)

[505681302]

Also, what does amphiprotic mean?

When a substance Can both donate and accept a proton.

[505681302]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

You have to know the list of strong and weak acids and bases

[jkenn123]

Hi! If the problem doesn't specify you will have to refer to the diagram which lists the strong and weak acids and bases! Hope this helps!!

[Roni Nissim 1D]

Also, what does amphiprotic mean?

Amphiprotic is when a compound is able to accept a proton and donate a proton. Basically this compound can act as both an acid and a base.

[Roni Nissim 1D]

What is the difference between K and Q reaction quotients. Does K only apply for reactions at equilibrium?

[Roni Nissim 1D]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

We have to memorize the strong acids and bases (and assume that the acids and bases that we see that are not strong are weak). There aren't many so it shouldn't be too extensive to memorize :)

[Vincent Cao 2D]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

A conjugate seesaw is the concept that the stronger the acid, the weaker its conjugate base. The stronger the base, the weaker its conjugate acid. This leads us to the formula pKa * pKb = pKw = 10^-14. pKa and pKb are inversely proportional since their product is a constant; if one number is higher, the other number has to be lower to get the same product. As a result a high pKa (weak acid), means a low pKb (stronger weak base) and vice versa.

Hi Angie, I think that pKa and pKb can only be added to equal pKw, which is 14. What you are referring to is Ka, Kb, and Kw, which deals with multiplication and numbers with exponents. However, a high pKa (weak acid) does create a low pKb (stronger conjugate base) and vice versa.

[Vincent Cao 2D]

What is the difference between K and Q reaction quotients. Does K only apply for reactions at equilibrium?

K reaction quotients refer to the concentrations or pressure ratio from the balanced chemical equation at equilibrium. Meanwhile, Q is basically the current ratio of the concentrations or pressure that you are measuring at that specific point in time t. It can be equal to K, which means that at time t the reaction has reached equilibrium. Refer to Le Chatelier's principle if Q is larger or smaller than K.

[705925790]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

I think you do, but bases are easy to remember since its group1 +2 hydroxides, and acids would be I, Cl, Br, SO4, NO3, and ClO4

[Abigail S 2C]

Does anyone have any good websites or video recommendations for acid and base problems ? Having trouble finding a good extra source!

[Abigail S 2C]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

I believe the Professor said the main list would be provided for us. But he did specifically mention that you could tell how strong an acid was from its pKa number if it is given to you, not sure if this works the same way for bases though.

[Abigail S 2C]

If the percentage ionization of an acid if greater than 5% and the approximation isn’t okay to use, how does on go about solving the problem? Normally using the quadratic formula, or is there a different way to do it?

[Rubani Chugh 2K]

Also, what does amphiprotic mean?

Amphiprotic means to have the ability to donate AND accept protons, which could also be thought of as as the ability to be a base or acid. For example, water is amphiprotic as its able to accept a proton, acting as an acid, (becoming H3O+) or donate a proton, acting as a base (becoming OH-).

[Rubani Chugh 2K]

In the equation where it says that pKw = pH + pOH = 14 at 25(degrees c) what does the p mean in the pKw section? And just to clarify the Kw refers to the equilibrium constant when water is involved right?

p in pKw refers to the -log of Kw which would be -log of 1*10^-14 =14. Yes, Kw refers to the equilibrium constant when water is involved and is equivalent to 1*10^-14.

[Rubani Chugh 2K]

Where do we find the answers to the recommended practice questions from the book?

If you open up the class on Canvas there should be a link titled "Chemical Principles, 7th Edition, Student Solutions Manual (Fundamentals, 1-7, 9)." Those are where you can find the answers. :)

The textbook answers can also be found at the back of the book if you select "Back matter" and then "odd numbered exercises" in the ebook.

[705586182]

What is the conjugate seesaw exactly? And what do we do when it is in a reaction?

Conjugate seesaw means that there is an inverse relationship between strong/weak base/acid with the respective conjugates. When identifying the strongest/weakest conjugate acid or base, for instance, if the question asks which base has the strongest conjugate acid, then you would look for the weakest base.

[Luke Smith]

Has anyone attempted practice problem 6b.11 from the textbook? I don't quite understand the math process for dealing with dilutions... does anyone have any recommended material that might help with that from 14A?

[Levon_Avedian_2H]

How do acids and bases relate with pH levels and substance concentrations?

[renee chowdhry 1A]

If a temperature is not given, can we assume we are solving at 25 degrees celcius?

Yes, I believe so! The temperature should be given in the problem, but if not, then I believe we can assume we are solving at 25 degrees Celsius.

[renee chowdhry 1A]

What is the difference between K and Q reaction quotients. Does K only apply for reactions at equilibrium?

K is the value that is reached after equilibrium, while Q is used before the reaction reaches equilibrium; it used to find which way the reaction is favored. K is like the final concentration while Q is like the concentration at a certain instant.

[renee chowdhry 1A]

How do we identify if something is a strong/weak acid or a strong/weak base?

[sally peterson]

Also, what does amphiprotic mean?

Something that is amphiprotic can either be an acid or a base meaning it can either donate or accept a proton! Water is an example because it can either lose a proton to become H+ and OH- or gain a proton to become H3O+

[905775469]

How do we identify if something is a strong/weak acid or a strong/weak base?

Dr. Lavelle sent out a list of them. He said it will be provided. Another trick is that a strong acid and a strong base form water and a salt.

[905775469]

How do acids and bases relate with pH levels and substance concentrations?

You can take the log of the concentration of either H+ or OH- to get the ph of something. Low ph <7= acidic. High pH>7= basic

[905775469]

What is an acid and a Base? How can you tell the difference? Have a nice day.

You can take the log of the concentration of OH- or H+ to determine the ph of a liquid. Using the pH, you can determine if a solution is acidic or basic. ph<7=acidic and ph>7=basic

[905775469]

What is an acid and a Base? How can you tell the difference? Have a nice day.

You can take the log of the concentration of OH- or H+ to determine the ph of a liquid. Using the pH, you can determine if a solution is acidic or basic. ph<7=acidic and ph>7=basic

[Paulina Martirossian 2F]

How do we identify if something is a strong/weak acid or a strong/weak base?

I believe there will be a list provided to us.

[Paulina Martirossian 2F]

Does anyone have any good websites or video recommendations for acid and base problems ? Having trouble finding a good extra source!

The organic chemistry tutor on YouTube has great videos explaining how to do acid and base problems.

[Nicole Pablico]

Which examples of strong acids and bases are we supposed to memorize?

[Paulina Martirossian 2F]

What is the difference between K and Q reaction quotients. Does K only apply for reactions at equilibrium?

K is the value that is reached when a reaction has reached equilibrium, and Q is the reaction quotient that determines what direction the reaction will move in.

[Nicole Pablico]

How to determine the change in concentration when making the ICE table?

[Nicole Pablico]

What is the relationship between conjugate strong/weak acids and conjugate weak/strong basicity?

[Nicole Pablico]

What is the relationship between conjugate strong/weak acids and conjugate weak/strong basicity?

[405735471]

Do we need to memorize certain acids or bases or will we be told whether or not it is a strong acid or base?

[Daniel Hong 3F]

The relationship between conjugate acids and bases that are strong and weak is that they are inversely related to each other which means the stronger the acid, the weak its conjugate base. The strong a base, the weaker it is a conjugate acid.

[005999765]

Is there a section for Acids and Bases on the 14B Chemistry Community section?

They are under chemistry 14A

[005999765]

Also, what does amphiprotic mean?

When something is amphiprotic, it means it is a proton donor and an acceptor.

[905988526]

What is the relationship between conjugate strong/weak acids and conjugate weak/strong basicity?

When there are weak conjugate acids with high pKa, the conjugate bases are strong and vice versa

[905988526]

Do we need to memorize certain acids or bases or will we be told whether or not it is a strong acid or base?

I would try and memorize the common ones that we use in class often. It would be good to have the previous knowledge of the acid and base during an exam.

[905988526]

How to determine the change in concentration when making the ICE table?

whichever the reaction needs to shift to is how you know how to make it a positive x or negatrive x, and then you use that and the amount of moles to either add or subtract from the inital concentration.

[Jane_S 2C]

Is there a section for Acids and Bases on the 14B Chemistry Community section?

Hello! Yes we are currently on the thread for Acids and Bases on the 14B section. All Acids and Bases material should be here

[Luke Smith]

If the equation is doesn't include a strong acid or base and we therefore cannot assume it completely dissociates, what do we do?

Hi, I think if you are working with a weak acid or base you have to add water into the chemical equation.

[Luke Smith]

If a temperature is not given, can we assume we are solving at 25 degrees celcius?

Yes, I'm pretty sure that if temperature isn't explicitly listed you can assume the reaction is occurring at 25 degrees Celsius.

[Jane_S 2C]

In the equation where it says that pKw = pH + pOH = 14 at 25(degrees c) what does the p mean in the pKw section? And just to clarify the Kw refers to the equilibrium constant when water is involved right?

p means 'taking the negative log' of something. For example, pH= p[H3O+] and therefore pH = -log(H30+)

[Jane_S 2C]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

My TA said we will have to just know most of the acids and bases and if they are strong or weak. However, in practice problems it usually clarifies.

[Julianne_Sue_3A]

Just a quick question:
Is there a way to determine whether something is weak or strong besides knowing how much something might dissociate? Would we have to memorize acids and bases that are weak and strong?

I found this website really helpful in identifying the strong/weak acids, it outlines which is which and also explains the characteristics and ionization reactions.

https://www.thoughtco.com/list-of-stron ... ids-603642

[Hoang Nguyen 3H]

It's in the 14A section.

[Hoang Nguyen 3H]

Does anyone know if we have to memorize strong acids and bases or will it be provided for us?

There should be a list provided for us.

[505968894]

How can you tell if a compound is acidic or basic?