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Strong or Weak - Sodium hydroxide, Calcium Bohr Model - How to draw Bohr diagram for Calcium, Is OH- an acid or base? It is poorly soluble in water. O CO32- O HCO32- O H2CO3 Remember the rules for writing displacement reactions. Several antacids have aluminum hydroxide, Al(OH)3, as an active ingredient. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. arrow . This functions as such: Furthermore, here is a table of common buffers. OIT: CHE 101 - Introduction to General Chemistry, { "7.01:_Acids_and_Bases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.02:_pH_and_pOH" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.03:_Relative_Strengths_of_Acids_and_Bases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.04:_Acid-Base_Neutralization" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.05:_Polyprotic_Acids" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.06:_Buffers" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7.07:_Unit_7_Practice_Problems" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "01:_Making_Measurements" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "02:_Atoms_and_the_Periodic_Table" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "03:_Chemical_Bonding" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "04:_Stoichiometry_of_Chemical_Reactions" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "05:_Activity_Series" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "06:_Concentrations" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "07:_Acid-Base_Equilibria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "08:_Gases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "zz:_Back_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "Author tag:OpenStax", "authorname:openstax", "showtoc:no", "license:ccby", "transcluded:yes", "source-chem-38279" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FOregon_Institute_of_Technology%2FOIT%253A_CHE_101_-_Introduction_to_General_Chemistry%2F07%253A_Acid-Base_Equilibria%2F7.04%253A_Acid-Base_Neutralization, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), 7.3: Relative Strengths of Acids and Bases, http://cnx.org/contents/85abf193-2bda7ac8df6@9.110, status page at https://status.libretexts.org. Answer: B acids are proton donors When HCl is added to pure water, HCl molecules lose protons, while water molecules gain protons. One of the most common antacids is calcium carbonate, CaCO3. We aim to make complex subjects, like chemistry, approachable and enjoyable for everyone. Water is the acid that reacts with the base, \(\ce{HB^{+}}\) is the conjugate acid of the base \(\ce{B}\), and the hydroxide ion is the conjugate base of water. Carbonate ions from the carbonate react with hydrogen ions from the acid. In an acidbase reaction, an acid plus a base reacts to form a conjugate base plus a conjugate acid. This is sometimes true, but the salts that are formed in these reactions may have acidic or basic properties of their own, as we shall now see. I calculated n of calcium hydroxide: 0.0337 mol. ncdu: What's going on with this second size column? It is formed by mixing CaO (quicklime, or calcium oxide) with H2O (water). What is citric acid plus. Principles of Modern Chemistry. Is sulfide ion a stronger base than hydroxide ion? However, Ca (OH) 2 has a colourless appearance in its crystalline form. Belmont: Thomson Higher Education, 2008. . The instructor will test the conductivity of various solutions with a light bulb apparatus. This is often sloppily used by organic chemists, and can lead to confusion, especially with amines. The bonds are represented as: where A is a negative ion, and M is a positive ion. We aim to make complex subjects, like chemistry, approachable and enjoyable for everyone. The relative strengths of acids may be determined by measuring their equilibrium constants in aqueous solutions. The team at Topblogtenz includes experts like experienced researchers, professors, and educators, with the goal of making complex subjects like chemistry accessible and understandable for all. For strong acids, you can calculate the pH by simply taking the negative logarithm of its molarity as it completely dissociates into its conjugate base and hydronium. It ionizes and forms hydronium ions and carbonate ions in even smaller quantities. A strong acid and a strong base, such as HCl(. It is an inorganic compound which has a white, powdery appearance in its solid-state. For the reaction of an acid \(\ce{HA}\): we write the equation for the ionization constant as: \[K_\ce{a}=\ce{\dfrac{[H3O+][A- ]}{[HA]}}\]. The conjugate acid of NO 2 is HNO 2; Ka for HNO 2 can be calculated using the relationship: Ka Kb = 1.0 10 14 = Kw Solving for Ka, we get: Ka = Kw Kb = 1.0 10 14 2.17 10 11 = 4.6 10 4 This answer can be verified by finding the Ka for HNO 2 in Table E1 Exercise 6.4.2 Kb for \(\ce{NO2-}\) is given in this section as 2.17 1011. The beneficial bacteria feed on starches in the cucumber and produce lactic acid as a waste product in a process called fermentation. Adding these two chemical equations yields the equation for the autoionization for water: \[\cancel{\ce{HA}(aq)}+\ce{H2O}(l)+\cancel{\ce{A-}(aq)}+\ce{H2O}(l)\ce{H3O+}(aq)+\cancel{\ce{A-}(aq)}+\ce{OH-}(aq)+\cancel{\ce{HA}(aq)}\], \[\ce{2H2O}(l)\ce{H3O+}(aq)+\ce{OH-}(aq)\]. Similarly, base strength decreases and conjugate acid strength increases down the table. Skip to main content. Again, like the strong acids, the strong bases are completely ionized in water solution. How to tell which packages are held back due to phased updates. The first ionization of carbonic acid yields hydronium ions and bicarbonate ions in small amounts. 1 You can judge the relative strength of a conjugate by the \(K_a\) or \(K_b\) . The extent to which a base forms hydroxide ion in aqueous solution depends on the strength of the base relative to that of the hydroxide ion, as shown in the last column in Figure \(\PageIndex{3}\). How to know if Ca(OH)2 is acid or base practically? . Figure out what thereactants and products will be. In solutions of the same concentration, stronger acids ionize to a greater extent, and so yield higher concentrations of hydronium ions than do weaker acids. The bicarbonate ion can also act as an acid. This is the most complex of the four types of reactions. A higher Ka value means a higher ratio of reactants to products, and so the acid with the higher Ka value will be producing more hydronium, and therefore have a lower pH. where the concentrations are those at equilibrium. The cations will switch places in the products for double replacement reactions. The Ka value for acetic acid is 1.76*10-5, and the Ka value for benzoic acid is 6.46*10-5, if two solutions are made, one from each acid, with equal concentrations, which one will have the lower pH? Vishal Goyal is the founder of Topblogtenz, a comprehensive resource for students seeking guidance and support in their chemistry studies. This means that little of the \(\ce{HCO3-}\) formed by the ionization of H2CO3 ionizes to give hydronium ions (and carbonate ions), and the concentrations of H3O+ and \(\ce{HCO3-}\) are practically equal in a pure aqueous solution of H2CO3. Sodium hydroxide is a strong base, and it will not make a buffer solution. Required fields are marked *. Stack Exchange network consists of 181 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers. For polyprotic acids, successive ionizations become weaker in a stepwise fashion and can usually be treated as separate equilibria. Notify me of follow-up comments by email. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. It is used to clarify raw juice from sugarcane in the sugar industry. First week only $4.99! When hydrochloric acid reacts with hydroxide ion, water and chloride ion are formed. Therefore, in this system, most H+ will be in the form of a hydronium ion H3O+ instead of attached to a Cl anion and the conjugate base will be weaker than a water molecule. Legal. A weaker acid has a stronger conjugate base. After HCl donates a proton, a Cl - ion is produced, and so Cl - is the conjugate base. It is used as a pH modifier. Thus, the strengths of an acid and its conjugate base are inversely related, as shown in(Figure \(\PageIndex{2}\)). If acetic acid, a weak acid with the formula CH3COOH, was made into a buffer solution, it would need to be combined with its conjugate base CH3COO in the form of a salt. A second common application with an organic compound would be the production of a buffer with acetic acid. Thus a stronger acid has a larger ionization constant than does a weaker acid. \]. HA(aq) + H 2O(l) H 3O + (aq) + A (aq) Water is the base that reacts with the acid HA, A is the conjugate base of the acid HA, and the hydronium ion is the conjugate acid of water. The single arrow used in the above reaction shows that only forward reaction takes place at equilibrium and no backward reaction occurs in solution. (OH) 2 - calcium hydroxide Sr(OH) 2 - strontium . 2012-09 . They are less reactive compare to a strong base. A similar concept applies to bases, except the reaction is different. This page titled 7.4: Acid-Base Neutralization is shared under a CC BY license and was authored, remixed, and/or curated by OpenStax. The reaction, \[CaCO_3(s)+2HCl(aq)CaCl_2(aq)+H_2O(l)+CO_2(g)\]. The ionization constant of \(\ce{NH4+}\) is not listed, but the ionization constant of its conjugate base, NH3, is listed as 1.8 105. When one of these acids dissolves in water, their protons are completely transferred to water, the stronger base. Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula Ca() 2.It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water.It has many names including hydrated lime, caustic lime, builders' lime, slaked lime, cal, and pickling lime.Calcium hydroxide is used in many applications, including food . The strength of a conjugate acid is directly proportional to its dissociation constant. Nitric acid has the chemical formula HNO3, and Calcium Hydroxide has the chemical formula Ca (OH)2. The base dissociation constant, K b, is a measure of basicitythe base's general strength. In most cases, polyprotic acids lose their protons one at a time, withKa1>>Ka2>>Ka3etc. As we have seen in the section on chemical reactions, when an acid and base are mixed, they undergo a neutralization reaction. So, the higher the value of the base dissociation constant, the larger is the strength of a base in solution. When placed in water, virtually every HCl molecule splits into a H+ ion and a Cl- ion in the reaction.1, \[\ce{HCl(aq) + H2O(l) <=> H3O^{+}(aq) + Cl^{-}(aq)} \nonumber\], For a strong acid like HCl, if you place 1 mole of HCl in a liter of water, you will get roughly 1 mole of H30+ ions and 1 mole of Cl- ions. Why did Ukraine abstain from the UNHRC vote on China? [3] An example of this case would be the dissociation of hydrochloric acid HCl in water. Cooking is essentially synthetic chemistry that happens to be safe to eat. If Kb < 1, then the nature of the compound is a weak base. What is the purpose of this D-shaped ring at the base of the tongue on my hiking boots? 2 is combined with sodium, calcium and potassium cations and chloride anions in distilled water . The conjugate acid of NO 2 is HNO 2; Ka for HNO 2 can be calculated using the relationship: Ka Kb = 1.0 10 14 = Kw Solving for Ka, we get: Ka = Kw Kb = 1.0 10 14 2.17 10 11 = 4.6 10 4 This answer can be verified by finding the Ka for HNO 2 in Table E1 Exercise 14.3.2 An base dissociation constant(Kb) is a quantitative measure of the strength of an base in solution. The alternate names of this compound include hydrated lime, slack lime, pickling . However, the conjugate base of the weak acid is a weak base and ionizes slightly in water. Weak acids do not readily break apart as ions but remain bonded together as molecules. To write the ionic equation we must separate all aqueous species into their ions and leave any solid, liquid or gaseous substance in its molecular form. All rights Reserved, Calcium hydroxide is white in color appears as a granular solid that has no odor with the chemical formula Ca(OH), In this article, we will discuss Is Calcium hydroxide (CaOH. All soluble hydroxides like lithium, cesium, sodium, potassium, etc. Weak acids are only partially ionized because their conjugate bases are strong enough to compete successfully with water for possession of protons. The ionization constants increase as the strengths of the acids increase. These acids are completely dissociated in aqueous solution. If a conjugate acid is strong, its dissociation will have a higher equilibrium constant and the products of the reaction will be favored. In this case, the water molecule is the conjugate acid of the hydroxide ion after the latter received the hydrogen ion donated by ammonium. Bases that are weaker than water (those that lie above water in the column of bases) show no observable basic behavior in aqueous solution. A stronger acid has a weaker conjugate base. We will discover the relationship between molecular structure and acids-bases, and think about water solutions of acids and bases. are alkali metals. PH is based on the concentration of the hydronium ion (H3O+) which is a product of the reaction of acid and water. Strong or Weak - Formic. This is the question: A 2.50 g tablet of calcium hydroxide is dissolved in 400.0 mL of water. Phase 2: Understanding Chemical Reactions, { "6.1:_Review:_Defining_Acids_and_Bases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.2:_BrnstedLowry_Acids_and_Bases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.3:_The_pH_Scale" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.4:_Acid-Base_Strength" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.5:_Solving_Acid-Base_Problems" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.6:_Acidic_and_Basic_Salt_Solutions" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.7:_Lewis_Acids_and_Bases" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "4:_Kinetics:_How_Fast_Reactions_Go" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "5:_Equilibrium:_How_Far_Reactions_Go" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6:_Acid-Base_Equilibria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "7:_Buffer_Systems" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "8:_Solubility_Equilibria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "weak acid", "oxyacid", "percent ionization", "showtoc:no", "license:ccbyncsa", "source-chem-25230", "source-chem-38278", "licenseversion:40" ], https://chem.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fchem.libretexts.org%2FCourses%2FBellarmine_University%2FBU%253A_Chem_104_(Christianson)%2FPhase_2%253A_Understanding_Chemical_Reactions%2F6%253A_Acid-Base_Equilibria%2F6.4%253A_Acid-Base_Strength, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), \[\dfrac{8.110^{3}}{0.125}100=6.5\% \], Calculation of Percent Ionization from pH, http://cnx.org/contents/85abf193-2bda7ac8df6@9.110, status page at https://status.libretexts.org, Assess the relative strengths of acids and bases according to their ionization constants, Understand trends in the relative strengths of conjugate acid-base pairs and polyprotic acids and bases, \(K_\ce{a}=\ce{\dfrac{[H3O+][A- ]}{[HA]}}\), \(K_\ce{b}=\ce{\dfrac{[HB+][OH- ]}{[B]}}\), \(K_a \times K_b = 1.0 \times 10^{14} = K_w \,(\text{at room temperature})\), \(\textrm{Percent ionization}=\ce{\dfrac{[H3O+]_{eq}}{[HA]_0}}100\). Example- Ammonia (NH3), Methylamine (CH3NH2), NH4OH,etc. Ca(OH)2 is a base. Let us illustrate this system using the neutralization of hydrochloric acid with sodium hydroxide. So, more proton acceptors present in the solution ultimately make Ca(OH), An alkali is said to be strongest when it produces almost all OH, According to the Arrhenius theory, the compound is said to be base when it produces OH, Is Ba(OH)2 strong base or weak base? What is the conjugate acid of the carbonate ion? Therefore, the buffer solution resists a change in pH. 1. If it has a bunch of hydroxide ions, it's a base. 2 years ago. It is also used in the treatment of sewage water as a clarifying agent. document.getElementById("ak_js_1").setAttribute("value",(new Date()).getTime()); Topblogtenz is a website dedicated to providing informative and engaging content related to the field of chemistry and science. It is also used in the treatment of sewage water as a clarifying agent. On the other hand, a conjugate base is what is left over after an acid has donated a proton during a chemical reaction. A stronger base has a larger ionization constant than does a weaker base. All acids and bases do not ionize or dissociate to the same extent. This leads to the statement that acids and bases are not all of equal strength in producing H+ and OH- ions in solution. For an acid, the reaction will be HA + H2O --> A- + H3O+ . Litmusis awater-solublemixture of differentdyesextractedfromlichens. A conjugate acid is formed by accepting a proton (H + ). Strong acids have mostly ions in solution, therefore the bonds holding H and A together must be weak. As we did with acids, we can measure the relative strengths of bases by measuring their base-ionization constant (Kb) in aqueous solutions. Let's connect through LinkedIn: https://www.linkedin.com/in/vishal-goyal-2926a122b/, Your email address will not be published. Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license. Last edited on 21 February 2023, at 02:22, "Strength of Conjugate Acids and Bases Chemistry Tutorial", MCAT General Chemistry Review - 10.4 Titration and Buffers. The percent dissociation of an acid or base is mathematically indicated by the acid ionization constant (Ka) or the base ionization constant (Kb)1. The relative strength of an acid or base depends on how high its Ka or Kb value is, in this case, the Ka value is far lower than the Kb value so the ammonia is more strongly basic than ammonium is acidic. Paul Flowers (University of North Carolina - Pembroke),Klaus Theopold (University of Delaware) andRichard Langley (Stephen F. Austin State University) with contributing authors. It means only some parts of the weak base dissociate in the solution to give OH ion but some parts remain undissociated inside the solution. It is used in the production of many plastics. Ca (OH)2 (calcium hydroxide) is a strong base (which means it cannot be an acid). Water is the base that reacts with the acid \(\ce{HA}\), \(\ce{A^{}}\) is the conjugate base of the acid \(\ce{HA}\), and the hydronium ion is the conjugate acid of water. Why are Suriname, Belize, and Guinea-Bissau classified as "Small Island Developing States"? Your email address will not be published. The following data on acid-ionization constants indicate the order of acid strength: \(\ce{CH3CO2H} < \ce{HNO2} < \ce{HSO4-}\), \[ \begin{aligned} \ce{CH3CO2H}(aq) + \ce{H2O}(l) &\ce{H3O+}(aq)+\ce{CH3CO2-}(aq) \quad &K_\ce{a}=1.810^{5} \\[4pt] \ce{HNO2}(aq)+\ce{H2O}(l) &\ce{H3O+}(aq)+\ce{NO2-}(aq) &K_\ce{a}=4.610^{-4} \\[4pt] \ce{HSO4-}(aq)+\ce{H2O}(aq) &\ce{H3O+}(aq)+\ce{SO4^2-}(aq) & K_\ce{a}=1.210^{2} \end{aligned}\]. Home > Chemistry > Is Ca(OH)2 an acid or base? When we make a solution of a weak polyprotic acid, we get a solution that contains a mixture of acids.