The Bronsted-Lowry acid in the chemical equation below is _____. pH: a measure of hydronium ion concentration in a solution. Get access to this video and our entire Q&A library. Those acids that lie between the hydronium ion and water in Figure \(\PageIndex{3}\) form conjugate bases that can compete with water for possession of a proton. WebWeak acids and the acid dissociation constant, K_\text {a} K a. All rights reserved. Write equations for the reaction of the PO_4/H_2PO_4 buffer reacting with an acid and a base. a. (a) 0.0450 (b) 4.53 (c) 9.86 times 10^{-5} (d) 0.442 (e) 4.87, The ionization of nitrous acid, HNO_2, in water can be described as, HNO_2(aq) leftrightarrow H^+(aq) + NO_2 ^-(aq) K_a = 4.5 times 10^{-4} (a) Calculate Delta G degree for the ionization of 0.10, For a weak acid with a dissociation constant K_a, find the initial acid concentration c_0, in terms of K_a, for which the acid is 50% dissociated. Show all the work in detail. We can tell by measuring the pH of an aqueous solution of known concentration that only a fraction of the weak acid is ionized at any moment (Figure \(\PageIndex{4}\)). Calculate the pH of a 0.557 M aqueous solution of nitrous acid (HNO_2, K_a = 4.5 times 10^{-4}) and the equilibrium concentrations of the weak acid and its conjugate base. As shown in the previous chapter on equilibrium, the \(K\) expression for a chemical equation derived from adding two or more other equations is the mathematical product of the other equations \(K\) expressions. A weak base yields a small proportion of hydroxide ions. The ionization constant of \(\ce{HCN}\) is given in Table E1 as 4.9 1010. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. Its freezing point is -0.2929 u001fC. To learn more, see our tips on writing great answers. HCN a) What is the dissociation equation in an aqueous Thus there is relatively little \(\ce{A^{}}\) and \(\ce{H3O+}\) in solution, and the acid, \(\ce{HA}\), is weak. The remaining weak base is present as the unreacted form. Both H+ and H3O+ are only symbolical and don't truly reflect hydration of proton. The following example shows that the concentration of products produced by the ionization of a weak base can be determined by the same series of steps used with a weak acid. WebCalculate the percent dissociation of a weak acid in a 0.060M solution of HA (K a = 1.5 10 5 ). Because\(\textit{a}_{H_2O}\) = 1 for a dilute solution, Ka= Keq(1), orKa= Keq. a. AsH_4^+ b. H_2C_3H_5O_7^- c. H_2SO_3. What is the pH of a 0.085 M solution of nitrous acid (HNO_2) that has a K_a of 4.5 times 10^{-4}? Why did DOS-based Windows require HIMEM.SYS to boot? 0.22 c. 3.62 d. 12.19 e. 2.31, For nitrous acid, HNO2, Ka = 4.0 x 10^-4. The best answers are voted up and rise to the top, Not the answer you're looking for? Therefore, the above equation can be written as- Sulfonic acids are just an example. Plus, get practice tests, quizzes, and personalized coaching to help you Determine the concentration of H^+ ions from an aqueous solution of nitrous acid (HNO_2) 0.02 mol / L, knowing the degree of ionization of the acid is 3%. In this case, protons are transferred from hydronium ions in solution to \(\ce{Al(H2O)3(OH)3}\), and the compound functions as a base. Complete the equation. It only takes a few minutes to setup and you can cancel any time. WebHNO_2 (aq) + H_2O (l) to H_3O^+ (aq) + NO_2 ^- (aq) For the following acids: i. CH_3COOH ii. Can I use my Coinbase address to receive bitcoin? As we discuss these complications we should not lose track of the fact that it is still the purpose of this step to determine the value of \(x\). 16.6: Weak Acids is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by LibreTexts. If \(\ce{A^{}}\) is a weak base, water binds the protons more strongly, and the solution contains primarily \(\ce{A^{}}\) and \(\ce{H3O^{+}}\)the acid is strong. The product of these two constants is indeed equal to \(K_w\): \[K_\ce{a}K_\ce{b}=(1.810^{5})(5.610^{10})=1.010^{14}=K_\ce{w} \nonumber \]. We can solve this problem with the following steps in which x is a change in concentration of a species in the reaction: We can summarize the various concentrations and changes as shown here. Also this Also this Arrhenius/Bronsted division is kinda silly IMO. Calculate the Ka value of a 0.50 M aqueous solution of acetic acid ( CH3COOH ) with a pH of 2.52. Thus strong acids are completely ionized in aqueous solution because their conjugate bases are weaker bases than water. WebSo the negative log of 5.6 times 10 to the negative 10. {eq}HNO_{2(aq)} + H_{2}O_{(l)} \rightleftharpoons NO_{2(aq)}^{-} + H_{3}O^{+}_{(aq)} {/eq}, {eq}Ka = \frac{\left [ H_{3}O^{+}\right ]\left [NO_{2}^{-} \right ]}{\left [ HNO_{2}\right ]} {/eq}, {eq}\left [ H_{3}O \right ]^{+} = 10^{-3.28} {/eq}, {eq}\left [ H_{3}O \right ]^{+} = 5.2480\cdot 10^{-5} M {/eq}, {eq}\left [ H_{3}O \right ]^{+} = 5.2480\cdot 10^{-5} M = x M {/eq}, $$Ka = \frac{\left [ H_{3}O^{+}\right ]\left [NO_{2}^{-} \right ]}{\left [ HNO_{2}\right ]} = \frac{\left [ x M \right ]\left [x M \right ]}{\left [ (0.021 - x)M \right ]} = \frac{\left [ x^{2} M\right ]}{\left [ (0.021 - x)M \right ]} $$, $$Ka = \frac{(5.2480\cdot 10^{-5})^2M}{(0.021-5.2480\cdot 10^{-5}) M} = \frac{2.7542\cdot 10^{-7}}{0.02047} = 1.3451\cdot 10^{-5} $$, The solution has 2 significant figures. Weak acid: partially ionizes when dissolved in water. Write an expression for the acid ionization constant (Ka) for H2CO3. @Mithoron Good to know! The Eumenides by Aeschylus: Summary, Characters & Analysis, Frank Lloyd Wright: Biography, Architecture & Style, The Bretton Woods Agreement: Definition & Collapse, How to Pass the Pennsylvania Core Assessment Exam, Impacts of COVID-19 on Hospitality Industry, Managing & Motivating the Physical Education Classroom, Eating Disorders in Abnormal Psychology: Help and Review, Prentice Hall Biology Chapter 16: Evolution of Populations, Evaluating Research Findings: Tutoring Solution, Holt Geometry Chapter 4: Triangle Congruence, Quiz & Worksheet - Nonverbal Signs of Aggression, Quiz & Worksheet - Basic Photography Techniques, Quiz & Worksheet - Writ of Execution Meaning, Quiz & Worksheet - Process of Cell Division. Calculate the percent ionization of nitrous acid in a solution that is 0.311 M in nitrous acid (HNO_2) and 0.189 M in potassium nitrite (KNO_2). The (H+) in a 0.020 M solution of HNO2 is 3.0 x 10-3 M. What is the Ka of HNO2? We can rank the strengths of bases by their tendency to form hydroxide ions in aqueous solution. Calculate the percent ionization of nitrous acid, HNO2, in a 0.249 M solution. Select all that apply. Write the equation for the dissociation of acetic acid in water and label the acids and bases. Calculate the pH of a 0.0236 M aqueous solution of nitrous acid (HNO2, Ka = 4.5 10-4). Thanks for contributing an answer to Chemistry Stack Exchange! She has prior experience as an organic lab TA and water resource lab technician. Only a small fraction of a weak acid ionizes in aqueous solution. The acid dissociation constant, Ka, of carbonic acid (H2CO3) is 4.5 x 10-7. Find the pH of the following solution of mixture of acids. How much nitrous acid was used to prepare one liter of this solution? WebCalculate the fraction of HNO2 that has dissociated. An error occurred trying to load this video. {/eq} values for weak acids are always less than 1 (often very much less). Step 1: Write the balanced dissociation equation for the weak acid. Screen capture done with Camtasia Studio 4.0. Write the acid-dissociation reaction of nitrous acid (HNO2) and its acidity constant expression. a. c) Construct (don't solve) the ICE chart for the acid dissociation of 0.250 M HONH_2. The chemical equation for the dissociation of HNO2 in water is: HNO2 (aq) H+(aq) + NO2- (aq)What are the equilibrium concentrations of HNO2 (aq) and NO2-(aq) and the pH of a 0.70 M HNO2 solution. This gives an equilibrium mixture with most of the base present as the nonionized amine. WebTranscribed Image Text: When HNO2 is dissolved in water, it partially dissociates accord- ing to the equation HNO2 = pared that contains 7.050 g of HNO2 in 1.000 kg of water. Choose the two Bronsted-Lowry acids in the equation HNO_2(aq) + H_2O(l) \to NO_2^-(aq) + H_3O^+(aq): a) \ HNO_2 \text{ and } H_2O \\ b) \ HNO_2 \text{ and } NO_2^{-} \\ c) \ HNO_2 \text{ and } H_3O^+ \\ d) \ H_2O \text{ and } H_3O^+ \\ e) \ NO_2^- \text{. The inability to discern differences in strength among strong acids dissolved in water is known as the leveling effect of water. At equilibrium, a solution contains [CH3CO2H] = 0.0787 M and \(\ce{[H3O+]}=\ce{[CH3CO2- ]}=0.00118\:M\). (b) HNO_2 vs. HCN. What is the Bronsted Acid in the following equation: * NO2- +H2O HNO2 + OH- **a. NO2- **b. H2O **c. HNO2 **d. OH- 2. Connect and share knowledge within a single location that is structured and easy to search. Determine the dissociation constants for the following acids. Nitrous acid is a weak monoprotic acid and the equilibrium equation of interest is HNO2 + H2O <-> H3O+ + NO2-. (The book was written by my teacher, I suppose he made a mistake in this exercise). In this reaction, a proton is transferred from one of the aluminum-bound H2O molecules to a hydroxide ion in solution. Recall that, for this computation, \(x\) is equal to the equilibrium concentration of hydroxide ion in the solution (see earlier tabulation): \[\begin{align*} (\ce{[OH- ]}=~0+x=x=4.010^{3}\:M \\[4pt] &=4.010^{3}\:M \end{align*} \nonumber \], \[\ce{pOH}=\log(4.310^{3})=2.40 \nonumber \]. Why do diacidic and triacidic alkalis dissociate in one step? Calculate the pH of a 0.0231 M aqueous solution of nitrous acid (HNO2, Ka = 4.5 x 10-4). Find the pH of a 0.015 M solution of HNO_2. Which of the following options correctly describe the effect of adding solid KClO2 to this system? b. Calculate the pH and the percent dissociation of each of the following solutions of benzoic acid. Both dissociations would be very fast, but not instantaneous. So: C6H5COOH---> C6H5COO- + H+ [H+] and [C6H5COO-] are yet to be. The percent ionization of a weak acid is the ratio of the concentration of the ionized acid to the initial acid concentration, times 100: \[\% \:\ce{ionization}=\ce{\dfrac{[H3O+]_{eq}}{[HA]_0}}100\% \label{PercentIon} \]. What is the H3O+ in a 0.60 M solution of HNO2? Chlorous acid, HClO_2, has an acid dissociation constant of 1.1 \times 10^{-2} \text{ at } 25^\circ C a) Write out the chemical reaction corresponding to this acid dissociation constant. 16.6: Weak Acids - Chemistry LibreTexts This table shows the changes and concentrations: 2. The amphoterism of aluminum hydroxide, which commonly exists as the hydrate \(\ce{Al(H2O)3(OH)3}\), is reflected in its solubility in both strong acids and strong bases. {/eq}, the dissociation reaction is: {eq}HA(aq) \rightleftharpoons H^+(aq) + A^-(aq) Experts are tested by Chegg as specialists in their subject area. lessons in math, English, science, history, and more. c. HNO_2 (nitrous acid). Learn more about Stack Overflow the company, and our products. A pH less than 7 indicates an acid, and a pH greater than 7 indicates a base. Thus, nonmetallic elements form covalent compounds containing acidic OH groups that are called oxyacids. At equilibrium, a solution of a weak base in water is a mixture of the nonionized base, the conjugate acid of the weak base, and hydroxide ion with the nonionized base present in the greatest concentration. 2. Spear of Destiny: History & Legend | What is the Holy Lance? The dissociation stoichiometry HA H + + AB tells us the concentrations [H +] and [A ] will be identical. When HNO2 dissolves in water, it partially dissociates The equilibrium concentration of HNO2 is equal to its initial concentration plus the change in its concentration. What is the pH of a solution that is 0.50 in NaNO2? Drive Student Mastery. There might be only 6 strong acids mentioned in your book, but it's by no means total number. Calculate the percent ionization of nitrous acid in a solution that is 0.253 M in nitrous acid (HNO2) and 0.111 M in potassium nitrite (KNO2). 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. Calculate the pH of a 0.97 M solution of carbonic acid. It only takes a minute to sign up. @Mithoron My teacher defined strong acids as those with a large Ka (as in too big to be measured). Show that the quadratic formula gives \(x = 7.2 10^{2}\). If we assume that x is small relative to 0.25, then we can replace (0.25 x) in the preceding equation with 0.25. The reaction of a Brnsted-Lowry base with water is given by: \[\ce{B}(aq)+\ce{H2O}(l)\ce{HB+}(aq)+\ce{OH-}(aq) \nonumber \]. Find the Ka value of carbonic acid when it dissociates in water. What is the Prisoner's Dilemma? a) Write the base dissociation reaction of HONH_2. Now we can fill in the ICE table with the concentrations at equilibrium, as shown here: Finally, we calculate the value of the equilibrium constant using the data in the table: \[K_\ce{a}=\ce{\dfrac{[H3O+][NO2- ]}{[HNO2]}}=\dfrac{(0.0046)(0.0046)}{(0.0470)}=4.510^{4} \nonumber \]. \(K_\ce{a}=\ce{\dfrac{[H3O+][A- ]}{[HA]}}\), \(K_\ce{b}=\ce{\dfrac{[HB+][OH- ]}{[B]}}\), \(K_a \times K_b = 1.0 \times 10^{14} = K_w \,(\text{at room temperature})\), \(\textrm{Percent ionization}=\ce{\dfrac{[H3O+]_{eq}}{[HA]_0}}100\). \(K_a\) for \(\ce{HSO_4^-}= 1.2 \times 10^{2}\). If \(\ce{A^{}}\) is a strong base, any protons that are donated to water molecules are recaptured by \(\ce{A^{}}\). To subscribe to this RSS feed, copy and paste this URL into your RSS reader. \[\ce{HCO2H}(aq)+\ce{H2O}(l)\ce{H3O+}(aq)+\ce{HCO2-}(aq) \hspace{20px} K_\ce{a}=1.810^{4} \nonumber \]. HNO3 Calculate the fraction of HNO, H* + NO2. Answer 0.0507 Upgrade to View Answer Discussion You must be signed in to discuss. I'm trying to learn, thank you for your understanding and your time. Carbonic acid dissociated into its conjugate base with K_a of 4.3 times 10^{-7}. and the {eq}K_a What is the value of \(K_a\) for acetic acid? \(x\) is given by the quadratic equation: \[x=\dfrac{b\sqrt{b^{2+}4ac}}{2a} \nonumber \]. Write an expression for the acid ionization constant (Ka) for HCHO2. Determine the ionization constant of \(\ce{NH4+}\), and decide which is the stronger acid, \(\ce{HCN}\) or \(\ce{NH4+}\). A strong base yields 100% (or very nearly so) of OH and HB+ when it reacts with water; Figure \(\PageIndex{1}\) lists several strong bases. What is the value of Kb for caffeine if a solution at equilibrium has [C8H10N4O2] = 0.050 M, \(\ce{[C8H10N4O2H+]}\) = 5.0 103 M, and [OH] = 2.5 103 M? Formic acid, HCO2H, is the irritant that causes the bodys reaction to ant stings. Acetic acid is the principal ingredient in vinegar; that's why it tastes sour. Write the equation for the dissociation of carbonic acid. The strengths of oxyacids also increase as the electronegativity of the central element increases [H2SeO4 < H2SO4]. Discover examples of strong and weak acids and bases. Solution This problem requires that we calculate an equilibrium concentration by determining concentration changes as the ionization of a base goes to equilibrium. Write the acid dissociation reaction. He has over 20 years teaching experience from the military and various undergraduate programs. Sorted by: 11. The chemical reactions and ionization constants of the three bases shown are: \[ \begin{aligned} \ce{NO2-}(aq)+\ce{H2O}(l) &\ce{HNO2}(aq)+\ce{OH-}(aq) \quad &K_\ce{b}=2.1710^{11} \\[4pt] \ce{CH3CO2-}(aq)+\ce{H2O}(l) &\ce{CH3CO2H}(aq)+\ce{OH-}(aq) &K_\ce{b}=5.610^{10} \\[4pt] \ce{NH3}(aq)+\ce{H2O}(l) &\ce{NH4+}(aq)+\ce{OH-}(aq) &K_\ce{b}=1.810^{5} \end{aligned} \nonumber \]. In each of these pairs, the oxidation number of the central atom is larger for the stronger acid (Figure \(\PageIndex{7}\)). Understand what weak acids and bases are. Write out the stepwise Ka reactions for citric acid (H3C6H5O7), a triprotic acid. In solvents less basic than water, we find \(\ce{HCl}\), \(\ce{HBr}\), and \(\ce{HI}\) differ markedly in their tendency to give up a proton to the solvent. Legal. c. Write the expression of. Thus, a weak acid increases the hydronium ion concentration in an aqueous solution (but not as much as the same amount of a strong acid). What is the concentration of hydronium ion and the pH in a 0.534-M solution of formic acid? d. HCN (hydrocyanic acid). Step 2: Create an Initial Change Equilibrium (ICE) Table for the disassociation of the weak acid. Psychological Research & Experimental Design, All Teacher Certification Test Prep Courses, How to Calculate the Ka of a Weak Acid from pH. Calculate the pH of 0.38 M KNO2. Write the expression of the equilibrium constant, Ka, for the dissociation of HX. Ka of nitrous acid is 4.50 x 10-4. For example, the oxide ion, O2, and the amide ion, \(\ce{NH2-}\), are such strong bases that they react completely with water: \[\ce{O^2-}(aq)+\ce{H2O}(l)\ce{OH-}(aq)+\ce{OH-}(aq) \nonumber \], \[\ce{NH2-}(aq)+\ce{H2O}(l)\ce{NH3}(aq)+\ce{OH-}(aq) \nonumber \]. Unlock Skills Practice and Learning Content. What is the equilibrium constant for the ionization of the \(\ce{HSO4-}\) ion, the weak acid used in some household cleansers: \[\ce{HSO4-}(aq)+\ce{H2O}(l)\ce{H3O+}(aq)+\ce{SO4^2-}(aq) \nonumber \]. Weak bases give only small amounts of hydroxide ion. Ms. Bui is cognizant of metacognition and learning theories as she applies them to her lessons. $$\ce{HSO4- <=> H+ + {SO_4}^2-}~~~~~~~~~~\ce{K_{a(2)}}=1.2\times10^{-2}$$, $$\ce{HSO4- + H2O <=> H3O+ +{SO_4}^2-}~~~~~~~~~~\ce{K_{a(2)}}= 1.2\times10^{-2}$$. A solution is prepared that contains 7.050 g of HNO2 in 1.000 kg of Step 3: The ionization constant of \(\ce{NH4+}\) is not listed, but the ionization constant of its conjugate base, \(\ce{NH3}\), is listed as 1.8 105. a. For a general weak acid, {eq}HA It only takes a few minutes. HNO2aq+H2OlH3O+aq+NO2- (aq) Then, we have given pH = 2.09 As pH is a measure of hydrogen ion concentration, a measure of the acidity or alkalinity of a solution so we have, pH=-log (H3O+) or 2.09=-log H3O+ or 10-2.09=H3O+ or H3O+=8.1*10-3 M In one mixture of NaHSO4 and Na2SO4 at equilibrium, \(\ce{[H3O+]}\) = 0.027 M; \(\ce{[HSO4- ]}=0.29\:M\); and \(\ce{[SO4^2- ]}=0.13\:M\). There's also a lot of inorganic acids, just less known, and their number is also probably limitless. Strong acids form very weak conjugate bases, and weak acids form stronger conjugate bases (Figure \(\PageIndex{2}\)). What is the pH of a buffer solution containing 0.12 m HNO_2 and NaNO_2? The acid dissociation constant of dichloroethanoic acid is 0.033. The reaction of an acid with water is given by the general expression: \[\ce{HA}(aq)+\ce{H2O}(l)\ce{H3O+}(aq)+\ce{A-}(aq) \nonumber \]. HNO2 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. equation 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. 16.4: Acid Strength and the Acid Dissociation Constant (Ka) Hydrogen the diatomic gas is simply not here. I know hydrogen is a diatomic gas, but here I don't know if H will dissociate as a gas or as a liquid (since $\ce{H2SO4}$ is a liquid, not a gas). A check of our arithmetic shows that \(K_b = 6.3 \times 10^{5}\). Now solve for \(x\). The acid-dissociation constant of sulfurous acid (H_2SO_3) are K_{a1} = 1.7 \times 10^{-2} and K_{a2} = 6.4 \times 10^{-8} at 25.0 degrees C. Calculate the pH of a 0.163 M aqueous solution of sulfurous acid. Log in here for access. As with acids, percent ionization can be measured for basic solutions, but will vary depending on the base ionization constant and the initial concentration of the solution. For example, it is often claimed that Ka= Keq[H2O] for aqueous solutions. Write the acid dissociation reaction. Any references? WebConsider the dissociation of the weak acid HClO2, which can be represented by the balanced equation HClO2 (aq) + H2O (l) ClO2- (aq) + H3O+ (aq). MathJax reference. For nitrous acid, HNO2, Ka = 4*10^-4. Chlorous acid. [A] HNO (aq) + H (aq) HNO (aq) [B] HNO (aq) H (aq) + NO^ (aq) [C] HNO (aq) NO (aq) + OH (aq) [D] HNO (aq) HNO (aq) + O (aq) [E] 2HNO (aq) 2H (aq) + N (g) + 3O (g) 06:09 Step 6: Simplify the expression and algebraically manipulate the problem to solve for Ka. Determine \(\ce{[CH3CO2- ]}\) at equilibrium.) \[\ce{HNO2}(aq)+\ce{H2O}(l)\ce{H3O+}(aq)+\ce{NO2-}(aq) \nonumber \], We determine an equilibrium constant starting with the initial concentrations of HNO2, \(\ce{H3O+}\), and \(\ce{NO2-}\) as well as one of the final concentrations, the concentration of hydronium ion at equilibrium. The chemical equation for the dissociation of HNO2 in water is: HNO2 (aq) H+(aq) + NO2- (aq). This accounts for the vast majority of protons donated by the acid. As a member, you'll also get unlimited access to over 88,000 The pH of a solution of household ammonia, a 0.950-M solution of NH3, is 11.612. A solution of 0.150 M HCN has a K_a = 6.2 times 10^{-10}. \(\ce{NH4+}\) is the slightly stronger acid (Ka for \(\ce{NH4+}\) = 5.6 1010). Add -SO3H group to one of millions organic groups and you have strong acid, voila! Ms. Bui has a Bachelor of Science in Biochemistry and German from Washington and Lee University. Ka is represented as {eq}Ka = \frac{\left [ H_{3}O^{+} \right ]\left [ A^{-} \right ]}{\left [ HA \right ]} {/eq}. Write the acid-dissociation reaction of nitrous acid (HNO_2) and its acidity constant expression. The acid dissociation constant of nitrous acid is 4.50 times 10^{-4}. As noted in the section on equilibrium constants, although water is a reactant in the reaction, it is the solvent as well, soits activityhas a value of 1, which does not change the value of \(K_a\). What is the K_a value for nitrous acid. Buffer solution pH calculations (video) | Khan Academy b. copyright 2003-2023 Study.com. Step 3: Write the equilibrium expression of Ka for the reaction. As we did with acids, we can measure the relative strengths of bases by measuring their base-ionization constant (Kb) in aqueous solutions. 8.0 x 10-3 b. Since 10 pH = Likewise nitric acid, HNO3, or O2NOH (N oxidation number = +5), is more acidic than nitrous acid, HNO2, or ONOH (N oxidation number = +3).