The pKa and pKb for an acid and its conjugate base are related as shown in Equation 16.5.15 and Equation 16.5.16. Why is it that some acids can eat through glass, but we can safely consume others? For sake of brevity, I won't do it, but the final result will be: This proportion is commonly refered as the alpha($\alpha$) for a given species, that varies from 0 to 1(0% - 100%). Bases, on the other hand, are molecules that accept protons (per Bronsted-Lowry) or donate an electron pair (per Lewis). The parameter standard bicarbonate concentration (SBCe) is the bicarbonate concentration in the blood at a PaCO2 of 40mmHg (5.33kPa), full oxygen saturation and 36C. Full text of the 'Sri Mahalakshmi Dhyanam & Stotram'. Asking for help, clarification, or responding to other answers. NH4+ is our conjugate acid. Numerically solving chemical equilibrium equations, Discrepancies in using pOH vs pH to solve H+/OH- concentration change problem. From your question, I can make some assumptions: Carbonic acid, $\ce{H2CO3}$, has two ionizable hydrogens, so it may assume three forms: The free acid itself, bicarbonate ion, $\ce{HCO3-}$(first-stage ionized form) and carbonate ion $\ce{CO3^2+}$(second-stage ionized form). For a given pH, the concentration of each species can be computed multiplying the respective $\alpha$ by the concentration of total calcium carbonate originally present. In contrast, acetic acid is a weak acid, and water is a weak base. The negative log base ten of the acid dissociation value is the pKa. Can Martian regolith be easily melted with microwaves? Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. B) Due to oxides of sulfur and nitrogen from industrial pollution. {eq}[OH^-] {/eq} is the molar concentration of the hydroxide ion. The higher the Ka value, the stronger the acid. Acid-Base Buffers: Calculating the pH of a Buffered Solution, Psychological Research & Experimental Design, All Teacher Certification Test Prep Courses, Maram Ghadban, Elizabeth (Nikki) Wyman, Dawn Mills, Using the Ka and Kb in Chemistry Problems, Experimental Chemistry and Introduction to Matter, LeChatelier's Principle: Disruption and Re-Establishment of Equilibrium, Equilibrium Constant (K) and Reaction Quotient (Q), Using a RICE Table in Equilibrium Calculations, Solubility Equilibrium: Using a Solubility Constant (Ksp) in Calculations, The Common Ion Effect and Selective Precipitation, Acid-Base Equilibrium: Calculating the Ka or Kb of a Solution, Titration of a Strong Acid or a Strong Base, NY Regents Exam - Physics: Help and Review, NY Regents Exam - Physics: Tutoring Solution, Middle School Earth Science: Help and Review, Middle School Earth Science: Tutoring Solution, Study.com ACT® Test Prep: Practice & Study Guide, ILTS Science - Environmental Science (112): Test Practice and Study Guide, Praxis Environmental Education (0831) Prep, ILTS Science - Earth and Space Science (108): Test Practice and Study Guide, Praxis Chemistry: Content Knowledge (5245) Prep, CSET Science Subtest II Life Sciences (217): Practice Test & Study Guide, How Acid & Base Structure Affect pH & pKa Values, How to Calculate the Acid Ionization Constant, Ionization Constants of Acids & Conjugate Bases, Wildlife Corridors: Definition & Explanation, Abiotic Factors in Freshwater vs. The reaction equations along with their Ka values are given below: H2CO3 (aq) <=====> HCO3- + H+ Ka1 = 4.3 X 107 mol/L; pKa1 = 6.36 at 25C Determine the value for the Kb and identify the conjugate base by writing the balanced chemical equation. See Answer Question: For which of the following equilibria does Kc correspond to the base-ionization constant, Kb, of HCO3? This is especially important for protecting tissues of the central nervous system, where pH changes too far outside of the normal range in either direction could prove disastrous (see acidosis or alkalosis). But at the same time it states that HCO3- will react as a base, because it's Kb >> Ka $\endgroup$ - Butyric acid is responsible for the foul smell of rancid butter. Notice that water isn't present in this expression. In a solution of carbonic acid, we have 1) water and 2) carbonic acid in the main. We know what is going on chemically, but what if we can't zoom into the molecular level to see dissociation? Enthalpy vs Entropy | What is Delta H and Delta S? In an acidbase reaction, the proton always reacts with the stronger base. It makes the problem easier to calculate. All chemical reactions proceed until they reach chemical equilibrium, the point at which the rates of the forward reaction and the reverse reaction are equal. $$\frac{\ce{[HCO3-]}}{Cs} = \ce{\frac{K1[H3O+]}{[H3O+]^2 + K1[H3O+] + K1K2}} = \alpha1$$, So we got the expression for $\alpha1$, that has a curious structure: a fraction, where the denominator is a polynomial of degree 2, and the numerator its middle term. {eq}[HA] {/eq} is the molar concentration of the acid itself. An error occurred trying to load this video. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Acid ionization constant: \[K_a=\dfrac{[H_3O^+][A^]}{[HA]}\], Base ionization constant: \[K_b=\dfrac{[BH^+][OH^]}{[B]} \], Relationship between \(K_a\) and \(K_b\) of a conjugate acidbase pair: \[K_aK_b = K_w \], Definition of \(pK_a\): \[pKa = \log_{10}K_a \nonumber\] \[K_a=10^{pK_a}\], Definition of \(pK_b\): \[pK_b = \log_{10}K_b \nonumber\] \[K_b=10^{pK_b} \]. We need a weak acid for a chemical reaction. With the expressions for all species, it's helpful to use a spreadsheet to automate the calculations for a entire range of pH values, to grasp in a visual way what happens with carbonates as pH changes. An acidic solution's pH is lower than 7, a basic solution's pH is higher than 7. Sodium Bicarbonate | NaHCO3 or CHNaO3 | CID 516892 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological . Why does Mister Mxyzptlk need to have a weakness in the comics? The higher value of Ka indicates the higher strength of the acid. Its Ka value is {eq}1.3*10^-8 mol/L {/eq}. This assignment sounds intimidating at first, but we must remember that pH is really just a measurement of the hydronium ion concentration. We could also have converted \(K_b\) to \(pK_b\) to obtain the same answer: \[K_a=10^{pK_a}=10^{10.73}=1.9 \times 10^{11}\]. Bicarbonate, also known as HCO3, is a byproduct of your body's metabolism. HCO3(aq) H+(aq) + Identify the conjugate base in the following reaction. Based on the Kb value, is the anion a weak or strong base? Ka in chemistry is a measure of how much an acid dissociates. Batch split images vertically in half, sequentially numbering the output files. The acid and base strength affects the ability of each compound to dissociate. Their equation is the concentration of the ions divided by the concentration of the acid/base. Has experience tutoring middle school and high school level students in science courses. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. At equilibrium the concentration of protons is equal to 0.00758M. | 11 O c. HCO3- (aq) + OH- (aq)-CO32- (aq) + H20 (/) O d. H2C03 (aq) + H2O (/)-HCO3Taq) + H3O+ (aq) O e. In darkness, when no photosynthesis occurs, respiration processes release carbon dioxide, and no new bicarbonate ions are produced, resulting in a rapid fall in pH. Let's go into our cartoon lab and do some science with acids! Decomposition of the bicarbonate occurs between 100 and 120C (212 and 248F): This reaction is employed to prepare high purity potassium carbonate. Remember that Henderson-Hasselbalch provides the equilibrium ratio of concentrations at a given pH. According to Wikipedia, the ${pKa}$ of carbonic acid, is 6.3 (and this is taking into account any aqueous carbon dioxide). Prinzip des Kleinsten Zwangs: Satz von LeChatelier, Begrndung von Gleichgewichtsverschiebungen durch thermodynamische Betrachtung: Zusammenhang von K und der Freien . Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. For example normal sea water has around 8.2 pH and HCO3 is . $K_b = 2.3 \times 10^{-8}\ (mol/L)$. Why does it seem like I am losing IP addresses after subnetting with the subnet mask of 255.255.255.192/26? potassium hydrogencarbonate, potassium acid carbonate, InChI=1S/CH2O3.K/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1, InChI=1/CH2O3.K/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1, Except where otherwise noted, data are given for materials in their, "You Have the (Baking) Power with Low-Sodium Baking Powders", "Why Your Bottled Water Contains Four Different Ingredients", "Powdery Mildew - Sustainable Gardening Australia", "Efficacy of Armicarb (potassium bicarbonate) against scab and sooty blotch on apples", Safety Data sheet - potassium bicarbonate, https://en.wikipedia.org/w/index.php?title=Potassium_bicarbonate&oldid=1107665193, Pages using collapsible list with both background and text-align in titlestyle, Articles containing unverified chemical infoboxes, Wikipedia articles incorporating a citation from the New International Encyclopedia, Creative Commons Attribution-ShareAlike License 3.0, This page was last edited on 31 August 2022, at 05:54. Ka = (4.0 * 10^-3 M) (4.0 * 10^-3 M) / 0.90 M. This Ka value is very small, so this is a weak acid. Ka is the dissociation constant for acids. Convert this to a ${K_a}$ value and we get about $5.0 \times 10^{-7}$. succeed. What ratio of bicarb to vinegar do I need in order for the result to be pH neutral? The following example shows how to find Ka from pH: The pH of a weak acid is equal to 2.12. What we need is the equation for the material balance of the system. At 25C, \(pK_a + pK_b = 14.00\). Calculate the acid dissociation constant for acetic acid of a solution purchased from the store that is 1 M and has a pH of 2.5. It works on the concept that strong acids are likely to dissociate completely, giving high Ka dissociation values. The higher the Kb, the the stronger the base. What is the significance of charge balancing when analysing system speciation (carbonate system given as an example)? In order to learn when a chemical behaves like an acid or like a base, dissociation constants must be introduced, starting with Ka. $$\ce{[H3O+]} = \frac{\ce{K1[H2CO3]}}{\ce{[HCO3-]}}$$, Or in logarithimic form: B is the parent base, BH+ is the conjugate acid, and OH- is the conjugate base. Use the dissociation expression to solve for the unknown by filling in the expression with known information. The best answers are voted up and rise to the top, Not the answer you're looking for? The conjugate acidbase pairs are listed in order (from top to bottom) of increasing acid strength, which corresponds to decreasing values of \(pK_a\). A solution of this salt is acidic . But how can I calculate $[\ce{HCO3-}]$ and $[\ce{CO3^2-}]$? Conjugate acids (cations) of strong bases are ineffective bases. The conjugate acid and conjugate base occur in a 1:1 ratio. For any conjugate acidbase pair, \(K_aK_b = K_w\). Styling contours by colour and by line thickness in QGIS. The table below summarizes it all. \(K_a = 1.4 \times 10^{4}\) for lactic acid; \(pK_b\) = 10.14 and \(K_b = 7.2 \times 10^{11}\) for the lactate ion. Let's start by writing out the dissociation equation and Ka expression for the acid. For the oxoacid, see, "Hydrocarbonate" redirects here. Learn how to use the Ka equation and Kb equation. Similarly, the equilibrium constant for the reaction of a weak base with water is the base ionization constant (Kb). Kb's negative log base ten is equal to pKb, it works the same as pKa expect that it's for bases. Should it not create an alkaline solution? Thanks for contributing an answer to Chemistry Stack Exchange! $$K1 = \frac{\ce{[H3O+][HCO3-]}}{\ce{[H2CO3]}} \approx 4.47*10^-7 $$, $$K2 = \frac{\ce{[H3O+][CO3^2-]}}{\ce{[HCO3-]}} \approx 4.69*10^-11 $$, $$K1K2 = \frac{\ce{[H3O+]^2[CO3^2-]}}{\ce{[H2CO3]}}$$, $$Cs = \ce{[CaCO3]} = \ce{[H2CO3] + [HCO3-] + [CO3^2-]}$$, $$Cs = \ce{[H2CO3] + [HCO3-] + [CO3^2-]}$$, $$Cs = \ce{\frac{[HCO3-][H3O+]}{K1} + [HCO3-] + \frac{K2[HCO3-]}{[H3O+]}}$$, $$Cs = \ce{\frac{[HCO3-][H3O+]^2 + K1[HCO3-][H3O+] + K1K2[HCO3-]}{K1[H3O+]}}$$, $$\frac{\ce{[HCO3-]}}{Cs} = \ce{\frac{K1[H3O+]}{[H3O+]^2 + K1[H3O+] + K1K2}} = \alpha1$$, $$\alpha0 = \frac{\ce{[H2CO3]}}{Cs} = \ce{\frac{[H3O+]^2}{[H3O+]^2 + K1[H3O+] + K1K2}}$$, $$\alpha2 = \frac{\ce{[CO3^2-]}}{Cs} = \ce{\frac{K1K2}{[H3O+]^2 + K1[H3O+] + K1K2}}$$, $$\ce{[H3O+]} = \frac{\ce{K2[HCO3-]}}{\ce{[CO3^2-]}}$$, $$pH = pK2 + log(\frac{\ce{[HCO3-]}}{[CO3^2-]})$$, $$\ce{[H3O+]} = \frac{\ce{K1[H2CO3]}}{\ce{[HCO3-]}}$$, $$pH = pK1 + log(\frac{\ce{[H2CO3]}}{[HCO3-]})$$. The Kb formula is quite similar to the Ka formula. pH is an acidity scale with a range of 0 to 14. Because the initial quantity given is \(K_b\) rather than \(pK_b\), we can use Equation 16.5.10: \(K_aK_b = K_w\). In the other side, if I'm below my dividing line near 8.6, carbonate ion concentration is zero, now I have to deal only with the pair carbonic acid/bicarbonate, pretending carbonic acid is just other monoprotic acid. The Ka expression is Ka = [H3O+][F-] / [HF]. Dawn has taught chemistry and forensic courses at the college level for 9 years. Can Martian regolith be easily melted with microwaves? The dissociation constant can be sought if information about the solution's pH was given. The conjugate base of a strong acid is a weak base and vice versa. If a exact result is desired, it's necessary to account for that, and use the constants corrected for the actual temperature. Study Ka chemistry and Kb chemistry. Does Magnesium metal react with carbonic acid? Once again, the concentration does not appear in the equilibrium constant expression.. We plug in our information into the Kb expression: 1.8 * 10^-5 = x^2 / 15 M. Solving for x, x = 1.6 * 10^-2. HCO3 and pH are inversely proportional. Find the pH. It is a white solid. These are the values for $\ce{HCO3-}$. For example, the general equation for the ionization of a weak acid in water, where HA is the parent acid and A is its conjugate base, is as follows: \[HA_{(aq)}+H_2O_{(l)} \rightleftharpoons H_3O^+_{(aq)}+A^_{(aq)} \label{16.5.1}\]. I would like to evaluate carbonate and bicarbonate concentration from groundwater samples, but I only have values of total alkalinity as $\ce{CaCO3}$, $\mathrm{pH}$, and temperature. Using Kolmogorov complexity to measure difficulty of problems? Their equation is the concentration . EDIT 2: I think you've realized your mistake; as you say, the values are for $\ce{HCO_3^-}$, which is the hydrogen carbonate ion. The constants \(K_a\) and \(K_b\) are related as shown in Equation 16.5.10. But unless the difference in temperature is big, the error will be probably acceptable. Why does it seem like I am losing IP addresses after subnetting with the subnet mask of 255.255.255.192/26? This order corresponds to decreasing strength of the conjugate base or increasing values of \(pK_b\). Normal pH = 7.4. There are no HCl molecules to be found because 100% of the HCl molecules have broken apart into hydrogen ions and chloride ions. Potassium bicarbonate is often found added to club soda to improve taste,[7] and to soften the effect of effervescence. Try refreshing the page, or contact customer support. $$K1K2 = \frac{\ce{[H3O+]^2[CO3^2-]}}{\ce{[H2CO3]}}$$, Analysing our system, to give a full treatment, if we know the solution pH, we can calculate $\ce{[H3O+]}$. The Ka formula and the Kb formula are very similar. Equation alignment in aligned environment not working properly, Difference between "select-editor" and "update-alternatives --config editor", Doesn't analytically integrate sensibly let alone correctly, Trying to understand how to get this basic Fourier Series. According to Gilbert N. Lewis, acids are also defined as molecules that accept electron pairs. To solve this problem, we will need a few things: the equation for acid dissociation, the Ka expression, and our algebra skills. Weak bases react with water to produce the hydroxide ion, as shown in the following general equation, where B is the parent base and BH+ is its conjugate acid: \[B_{(aq)}+H_2O_{(l)} \rightleftharpoons BH^+_{(aq)}+OH^_{(aq)} \label{16.5.4}\]. How do I quantify the carbonate system and its pH speciation? The equation is for the acid dissociation is HC2H3O2 + H2O <==> H3O+ + C2H3O2-. $K_a = 4.8 \times 10^{-11}\ (mol/L)$. Get unlimited access to over 88,000 lessons. The problem provided us with a few bits of information: that the acetic acid concentration is 0.9 M, and its hydronium ion concentration is 4 * 10^-3 M. Since the equation is in equilibrium, the H3O+ concentration is equal to the C2H3O2- concentration. Was ist wichtig fr die vierte Kursarbeit? They must sum to 1(100%), as in chemical reactions matter is neither created or destroyed, only changing between forms. To solve it, we need at least one more independent equation, to match the number of unknows. The best answers are voted up and rise to the top, Not the answer you're looking for? Calculate \(K_a\) for lactic acid and \(pK_b\) and \(K_b\) for the lactate ion. How do/should administrators estimate the cost of producing an online introductory mathematics class? For the bicarbonate, for example: All rights reserved. MathJax reference. It is a white solid. The plot that looks like a "XX" also allows us to see a interesting property of carbonates. Examples include as buffering agent in medications, an additive in winemaking. General Kb expressions take the form Kb = [BH+][OH-] / [B]. Great! The distribution of carbonate species as a fraction of total dissolved carbonate in relation to . This explains why the Kb equation and the Ka equation look similar. How do you get out of a corner when plotting yourself into a corner, Short story taking place on a toroidal planet or moon involving flying. The Ka equation and its relation to kPa can be used to assess the strength of acids. A) Due to carbon dioxide in the air. $$\alpha2 = \frac{\ce{[CO3^2-]}}{Cs} = \ce{\frac{K1K2}{[H3O+]^2 + K1[H3O+] + K1K2}}$$. Thus the conjugate base of a strong acid is a very weak base, and the conjugate base of a very weak acid is a strong base. 2018ApHpHHCO3-NaHCO3. The first was took for carbonates only and MO for carbonate + bicarbonate weighed sum. Acidbase reactions always proceed in the direction that produces the weaker acidbase pair. Step by step solutions are provided to assist in the calculations. But at the same time it states that HCO3- will react as a base, because it's Kb >> Ka, True, $HCO_3^-$ will react as both an acid and a base. This constant gives information about the strength of an acid. Consequently, aqueous solutions of acetic acid contain mostly acetic acid molecules in equilibrium with a small concentration of \(H_3O^+\) and acetate ions, and the ionization equilibrium lies far to the left, as represented by these arrows: \[ \ce{ CH_3CO_2H_{(aq)} + H_2O_{(l)} <<=> H_3O^+_{(aq)} + CH_3CO_{2(aq)}^- }\]. This is in-line with the value I obtained from a copy of Daniel C. Harris' Qualitative Chemical Analysis. To learn more, see our tips on writing great answers. When the calcium carbonate dissolves, a equilibrium is established between its three forms, expressed by the respective equilibrium equations: First stage: What are practical examples of simultaneous measuring of quantities? Follow Up: struct sockaddr storage initialization by network format-string. 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. Because the \(pK_a\) value cited is for a temperature of 25C, we can use Equation 16.5.16: \(pK_a\) + \(pK_b\) = pKw = 14.00. Nonetheless, I believe that your ${K_a}$ for carbonic acid is wrong; that number looks suspiciously like the ${K_a}$ instead for hydrogen carbonate ion (or the bicarbonate ion). It is equal to the molar concentration of the ions the acid dissociates into divided by the molar concentration of the acid itself. It is the only dry chemical fire suppression agent recognized by the U.S. National Fire Protection Association for firefighting at airport crash rescue sites. Because \(pK_b = \log K_b\), \(K_b\) is \(10^{9.17} = 6.8 \times 10^{10}\). If I have three species, but only two show up together at any given time, I can "forget" I'm dealing with a diprotic acid. {eq}[H^+] {/eq} is the molar concentration of the protons. How do I ask homework questions on Chemistry Stack Exchange? As we know the pH and K2, we can calculate the ratio between carbonate and bicarbonate. Look this question: How to calculate bicarbonate and carbonate from total alkalinity [closed]. Potassium bicarbonate (IUPAC name: potassium hydrogencarbonate, also known as potassium acid carbonate) is the inorganic compound with the chemical formula KHCO3. Many bicarbonates are soluble in water at standard temperature and pressure; in particular, sodium bicarbonate contributes to total dissolved solids, a common parameter for assessing water quality.[6]. In the lower pH region you can find both bicarbonate and carbonic acid. Thank you so much! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. The term "bicarbonate" was coined in 1814 by the English chemist William Hyde Wollaston. This is the equation given by my textbook for hydrolysis of sodium carbonate: $$\ce {Na2CO3 + 2 H2O -> H2CO3 + 2 Na+ + 2 OH-}$$. Rate Law Constant & Reaction Order | Overview, Data & Rate Equation, Boiling Point Elevation Formula | How to Calculate Boiling Point. This compound is a source of carbon dioxide for leavening in baking. Graduated from the American University of the Middle East with a GPA of 3.87, performed a number of scientific primary and secondary research. The Ka of NH4is 5.6x10- 10 and the Kb of HCO3 is 2.3x10-8. Bicarbonate is the dominant form of dissolved inorganic carbon in sea water,[9] and in most fresh waters. Nowhere in the plot you will find a pH value where we have the three species all in significant amounts. The values of Ka for a number of common acids are given in Table 16.4.1. 1KaKb 2[H+][OH-]pH 3 For help asking a good homework question, see: How do I ask homework questions on Chemistry Stack Exchange? All other trademarks and copyrights are the property of their respective owners. flashcard sets. How does carbonic acid cause acid rain when $K_b$ of bicarbonate is greater than $K_a$? The following questions will provide additional practice in calculating the acid (Ka) and base (Kb) dissociation constants. It is both the conjugate base of carbonic acidH2CO3; and the conjugate acid of CO23, the carbonate ion, as shown by these equilibrium reactions: A bicarbonate salt forms when a positively charged ion attaches to the negatively charged oxygen atoms of the ion, forming an ionic compound. The acid is HF, the concentration is 0.010 M, and the Ka value for HF is 6.8 * 10^-4. Bicarbonate (HCO3) is a vital component of the pH buffering system[3] of the human body (maintaining acidbase homeostasis). First, write the balanced chemical equation. For acids, these values are represented by Ka; for bases, Kb. The values of \(K_a\) for a number of common acids are given in Table \(\PageIndex{1}\). [7], Additionally, bicarbonate plays a key role in the digestive system. Use MathJax to format equations. We know that the Kb of NH3 is 1.8 * 10^-5. Hydrochloric acid, on the other hand, dissociates completely to chloride ions and protons: {eq}HCl_(aq) \rightarrow H^+_(aq) + Cl^-_(aq) {/eq}. It's called "Kjemi 1" by Harald Brandt. [1] A fire extinguisher containing potassium bicarbonate. Carbonic acid, $\ce{H2CO3}$, has two ionizable hydrogens, so it may assume three forms: The free acid itself, bicarbonate ion, $\ce{HCO3-}$ (first-stage ionized form) and carbonate ion $\ce{CO3^2+}$ (second-stage ionized form). We plug the information we do know into the Ka expression and solve for Ka. The full treatment I gave to this problem was indeed overkill. Ocean Biomes, Working Scholars Bringing Tuition-Free College to the Community. With carbonic acid as the central intermediate species, bicarbonate in conjunction with water, hydrogen ions, and carbon dioxide forms this buffering system, which is maintained at the volatile equilibrium[3] required to provide prompt resistance to pH changes in both the acidic and basic directions. The most common salt of the bicarbonate ion is sodium bicarbonate, NaHCO3, which is commonly known as baking soda. For acid and base dissociation, the same concepts apply, except that we use Ka or Kb instead of Kc. The magnitude of the equilibrium constant for an ionization reaction can be used to determine the relative strengths of acids and bases. $$Cs = \ce{[CaCO3]} = \ce{[H2CO3] + [HCO3-] + [CO3^2-]}$$, Where Cs here stands for the known concentration of the salt, calcium carbonate. For example, nitrous acid (\(HNO_2\)), with a \(pK_a\) of 3.25, is about a 1000 times stronger acid than hydrocyanic acid (HCN), with a \(pK_a\) of 9.21. It gives information on how strong the acid is by measuring the extent it dissociates. Homework questions must demonstrate some effort to understand the underlying concepts. Strong acids and bases dissociate well (approximately 100%) in aqueous (or water-based) solutions.