What is Acids and bases: Definition and 49 Discussions

An acid–base reaction is a chemical reaction that occurs between an acid and a base. It can be used to determine pH. Several theoretical frameworks provide alternative conceptions of the reaction mechanisms and their application in solving related problems; these are called the acid–base theories, for example, Brønsted–Lowry acid–base theory.
Their importance becomes apparent in analyzing acid–base reactions for gaseous or liquid species, or when acid or base character may be somewhat less apparent. The first of these concepts was provided by the French chemist Antoine Lavoisier, around 1776.

It is important to think of the acid-base reaction models as theories that complement each other. For example, the current Lewis model has the broadest definition of what an acid and base are, with the Brønsted-Lowry theory being a subset of what acids and bases are, and the Arrhenius theory being the most restrictive.

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  1. stuidvkook

    Chemistry Bronsted-Lowery Help: Understanding HCOOH + CN- and H2O + HCO3- Reactions

    1) HCOOH + CN- ---> HCOOH- + HCN 2) H2O + HCO3- <===> H3O+ + CO3-2
  2. StarChem

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  3. SilverSoldier

    Approximations in Chemical Equilibrium (add a weak acid HA into pure water)

    Suppose we add a weak acid HA into pure water, so that upon addition its initial concentration is c. The following equilibria should establish in the system. $$\text{HA}+\text{H}_2\text{O}\rightleftharpoons\text{H}_3\text{O}^++\text{A}^-$$...
  4. sergey_le

    Calculations involving acids and bases

    Summary:: finding ml of two solutions by the final pH i have a NaOAc 0.1M and HOAc 0.1M , together the volume of the solutions is 20ml and the pH is 4. I need to find the volume of each solution. I've tried to solve it for hours with no successes. i found the H+ concentration (-log(h)=4 ), it...
  5. R

    I am sure I am doing this Acid/Base problem wrong

    What is the pH of a solution made from 34.6 ml if 3.45*10^-4 M of H2SO4 added to 41.7 ml of 4.56*10^-4 M of Al(OH)3? I know how to find H+ and OH- and pH I also know how to use x mol / L, but I cannot get them to click together. Everyone keeps telling me to use RICE but my professor never...
  6. sidt36

    How can I distinguish between Lewis acids and bases?

    How do I know which species is a Lewis acid and which is a Lewis base?
  7. T

    Pouring acids and bases over sinks

    Homework Statement Which of the following would you not do in a laboratory setting? I. Pour acids and bases over a sink II. Wear goggles III. Heat a stoppered test tube (A) I only (B) II only (C) III only (D) I and III only (E) I, II, and III Homework Equations - The Attempt at a...
  8. E

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    Homework Statement The pKa of acetylsalicylic acid (aspirin) is 3.5. The pH of gastric juice in the stomach is about 2-3 and the pH in the small intestine is about 8. Aspirin will be Answer is ionised in the small intestine and almost unionised in the stomach. Homework EquationsThe Attempt at...
  9. Titan97

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    Homework Statement Which side does the equilibrium favour? Homework Equations Equilibrium favours weak acid or weak base (I don't know why :frown:) The Attempt at a Solution Using the given pka values, since the reactant is the weaker acid, reactants are favoured. (Backward reaction is...
  10. N

    When to Use Kw & Ka for Acid Dissociation Calculations

    So I've learned that in strong acids that dissociate completely, the concentration of H+ is the same as the concentration of the initial solution. So 1M of a strong acid will create 1M of H+, meaning the pH is 0. I've also learned that in weak acids, the whole thing doesn't dissociate. I have...
  11. Dong Aleta

    A question about the special case of calcium hydroxide

    Hi! I am having trouble understanding how a substance only slightly soluble in water is considered as a strong base. Isn't the definition of a base a substance that will increase the amount of OH- in a solution? In that case, shouldn't calcium hydroxide be considered a weak base because of its...
  12. Dong Aleta

    A question regarding the definition of acids and bases

    Hi! I just read in an inorganic chemistry book (by Whitten, et al.) that acids are defined as substances that produce H+ ions in dilute aqueous solutions, and bases are those that produce OH-. To me, this definition implies that a substance that has yet to produce an H+ or an OH- can already be...
  13. G

    What is the common property shared by all acids that leads to their definition?

    I've written the following brief history on how the definition of acids and bases change over time. Lavoisier came up with his definition circa 1776 in that 'p is acidic iff p contains much oxygen' and that held sway for 30 years[1] until it was falsified by Davy in 1810[2] who demonstrated...
  14. V

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    Homework Statement An aqueous effluent contains 12 M Cd2+ and 10 M Mg2+ as solution of nitrates. Current practice is use NaOH to selectively precipitate the metals. (a) Is it feasible to get 0 Cd impurities in Mg ppt by using NaF instead of NaOH (back up your answer with adequate calculations)...
  15. J

    Procedure of preparation of HCl

    Homework Statement Knowing that HCl is strong acid we want to prepare HCl solution of pH=4.2.starting from a solution of pH=2.9.Explain briefly the procedure that should be followed to do this operation. Homework Equations pH=-log(H3O+) 3. The Attempt at a Solution [/B] I calculated: At...
  16. iwantcalculus

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    < Mentor Note -- thread moved to HH from the technical PF forums, so no HH Template is shown > Hello! So our teacher puts some really hard questions in acids and bases exams, and I would like someone to help me find similar questions and know how to solve these questions.. So the first...
  17. C

    Calculating pH and pOH for 0.048 M Benzoic Acid Solution

    Homework Statement what is the H, Oh , ph and poh for a 0.048 mol/l solution of benzoic acid? C6H5COOH Homework Equations Ph +poh=14 Ph=-log(h30+) H30=10^-ph The Attempt at a Solution I thought maybe u need to separate benzoic acid into its ions and then use the molar ratio to...
  18. 2

    Calculating H3O+ Concentration for Acetic Acid Solution | Ka = 1.8 x 10-5

    Homework Statement What is the H3O+ concentration of a 0.100 M acetic acid solution (Ka = 1.8 x 10-5)? a. 1.8 x 10-5 b. 1.8 x 10-4 c. 1.3 x 10-2 d. 1.3 x 10-3 e. 0.9 x 10-3 Homework Equations The Attempt at a Solution so the question is supposed to be D. but I thought that...
  19. K

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    Lets say a certain chemical reacts with an acid. Does that make that chemical a base always and vice versa? Like in S + NaOH → Na2S + Na2S2O3, Sulfur reacting with a base would it make S an acid? Or do we call it a base or an acid, reacting with the opposite if it's producing water as a...
  20. J

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  21. M

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  22. K

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  23. R

    Acids and Bases. How to tell if a compound is an acid or base or neautral?

    I've been given a question on how to tell whether a compound is an acid or base or neautral in an aquesous solution. Na2CO3 Please help.
  24. D

    Why can the mixing of acids and bases be dangerous

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  25. P

    Why Do My Amphoteric Equations Keep Going Wrong?

    Homework Statement I'm having problems understanding amphoteric acids and bases. I know amphoteric means that it can act as an acid or base, but when the question asks me to write the equation to support this statement, I always get it wrong :confused: Homework Equations HSO4^-1 is an...
  26. U

    Understanding Lewis Acids & Bases: HCl, H2SO4, H3PO4, CO2, HCN

    hi all! I am not able to understand what's a Lewis acid and a Lewis base. tell me if these are Lewis acids or Lewis bases and tell me the reason. HCl, H2SO4, H3PO4, CO2, HCN. my approach: first 3 I'm not able to decide. 4th one I thought to be Lewis base as 2lone pairs of electrons left in...
  27. B

    Simple acids and bases question

    Sorry guys, I can't seem to grasp the concept: It deals with acids and bases. When the acid donates the proton, to the base, how do we know how many is transferred and how many the base can accept? This is where I am stumped. Homework Statement What ions are formed when nitric...
  28. P

    How do I classify acids and bases in chemistry?

    Can anyone explain to me how to determine whether a compound is a strong acid, weak acid, strong base, weak base, or amphoteric? Thanks!
  29. L

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    This is a subject I am unfamiliar with, and was just wondering where I should start in order to learn about them and how they affect different elements and form other substances step-by-step. From what I know, an Acid donated a Hydrogen Ion, and a Base takes a Hydrogen Ion, and an Acid has to...
  30. L

    How Does the Buffering Action of Weak Acids Change During Titration?

    Homework Statement I'm a little confused, let's say i do a titration curve for a weak acid, at some point there's a buffering range near the pKa. Like i know that if we add a strong base like NaOH to acetic acid in a water solvent, then the OH- will combine with the H+ (hydronium ion) which...
  31. W

    Mixtures of Acids and Bases: What Type of Solution is Produced?

    Homework Statement You prepared a reaction table for 10.0 mL of 0.1 M NH4Cl with 5.0 mL of 0.1 M NaOH. Please choose all of the following that describe the solution that was produced. The choices are: 1. a solution containing only a strong base 2. a solution containing a weak acid and a...
  32. L

    Differentiating Acids and Bases Based on Chemical Formulas

    Homework Statement does anyone know how i can differentiate a strong acid from a weak acid and likewise for a strong base and a weak base based on its chemical formula? Homework Equations The Attempt at a Solution
  33. S

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    I was looking for information in regard to Acids and Bases. I'm having a awful time with conceptual questions concerning this chapter in class, and I'm getting pretty frustrated. Any practice questions / supplemental in depth tutorials would be nice. Thanks!
  34. D

    Experimenting with Acids & Bases: DeltaH, Dissociation & Bond Strength

    I did an experiment with a) strong acid (HCl) and strong base (NaOH) b) weak acid (ethanoic) and strong base (NaOH) so, I am looking at the heat of energy for both the reactions, and so i found that reaction a had a greater heat of energy was that of the reaction b) weak acid and...
  35. D

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    Homework Statement Some of the books I have state that the equation of... HCl + NH3 --> NH4+ + Cl- While others state that the above equation should be written as... HCl + NH3 --> NH4Cl Which one is correct? I think the answer should be the second one since the two compounds...
  36. C

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  37. P

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    im looking at some review problems my teacher gave me today, and i can pretty much do most of them. however, there is this one i really have no idea what to do. Its a 2 part problem. 1a.What is the pH of a 1000 ml of a 0.1 M acetic acid solution, given pKa = 4.8? 1b. what is the pH of...
  38. L

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    Anyone clever with bronsted acids and bases? I'm pretty new in chemistry, but I'm trying to learn. Right now I'm suppose to classify some species as either bronsted acids or bases, or even both. For example 1. Water 2. OH- 3. NH4+ 4. HCN 5. HBr 6. NH3 Hope someone can help...
  39. B

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    I am a little stuck on this question : Solution A contains n moles of a weak acid HX. The addition of some sodium hydroxide to A neutralises one third of the HX present to produce Solution B. In terms of the amount, n how many moles of HX are present in Solution B? I think there are one...
  40. D

    Solving Organic Chemistry: Acids & Bases Problems

    I have problem in complete understanding these concepts especialy in organic chemistry. Inorganic was simple HaON, HCl and similar, but now in organic chemistry Acids and Bases concept and fast determining of those is killing me :(. Is there a place on internet with good tutorial covering...
  41. A

    Finding pH Values for Acids and Bases Without Experiments

    I have to place two acids and two bases from a previous assignment on a pH scale using the information I acquired during that particular experiment. The problem is, I couldn't get all the materials I needed so I didn't get to do the assignment. I've been able to figure out what vinegar's pH is...
  42. D

    Is My Acid-Base Mixture Actually Neutral?

    In my chmeistry lab i use a pipet 5.0 ml of HCl and add it to a beaker. To this beaker I also added 5.0 ml NaOH. I stir the mixture and when a red litmus it turn to blue and when i put a blue litmus it stay blue. So that means its a base, but since its a mixture of an acid and a base shouldn't...
  43. D

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    Uggh finally did all the chem problems and studied for the upcoming final but there are 2 questions left unanswered. MAybe someone can help me out with this: If given a lists of acids, how would one know which 1 is the weakest conjugate base? For example, HF, HNO_2, H_2CO_3, H_3BO_3, HCl...
  44. J

    Calculate pH & Concentration of Acids & Bases in Solution

    Could You Help Me Out With This Question Please: 25.0 cm3 of a solution of 0.1M ethanoic acid is titrated with 0.1M sodium hydroxide.When sufficient alkali has been added to neutralise half of the acid,calculate a)the concentration of ethanoic acid and ethanoate ions b)the pH of the...
  45. J

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    Hi People , I had a problem solving this question,could you please help me:D The question: a)The ionisation constant for propanoic acid is 1.26x10^-5 mol dm^-3.Calculate pH of a 1.0M solution b)What is the hydroxide ion concentration of this solution? c)Pocroc acid has an ionisation...
  46. J

    pH of Pure Water at 100°C | Acids & Bases

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  47. J

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    Hello People, I am a new member and i really think this forum is very helpful... I got a question... The pH values of 0.100moldm-3 solutions of hydrocloric acid and ethanoic acid are 1 and aproximately 3 respectively. Explain the difference. Thanks already...
  48. E

    Explaining Acids and Bases to a Six-Year-Old

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