This result clearly tells us that HI is a stronger acid than \(HNO_3\). TCC's nitric acid belongs to the group of inorganic acids. Measure out an amount of the analyte (it should be less than the amount in your burette) and add it to an Erlenmeyer flask. Recall from Chapter 4 that the acidic proton in virtually all oxoacids is bonded to one of the oxygen atoms of the oxoanion. For more tools about acids and bases, have a look at our neutralization calculator or learn how to calculate pH of buffer solution as well! The Ka value is a measure of the ratio between reactants and products at equilibrium. This calculator calculates for concentration or density values that are between those given in the table below by a process called interpolation. so, 0.7246 ml of 69% Nitric acid added with 99.275 ml of water forms 100 ml of 0.5% Nitric acid. You may notice on the titration curve that the pH will rise sharply around the equivalence point. An acid is a solution that has an excess of hydrogen (H+) ions. N o 3 point: let's do it 1.49 grams of h, n o 3. Note the start point of the solution on the burette. Here, we have used, As noted above, weight refers to mass (i.e., measured on a balance). (@37.5%) = 12.2 moles (range 11.85 - 12.34) Boiling Point 110C (230F) Nitric Acid. NO 3-Nitrate ion-----Hydronium ion. For example, commercially available concentrated hydrochloric acid (HCl) is 37% by weight (w/w %). Secondly, you could measure the density of the acid either by using a hydrometer or weighi. The calculator uses the formula M 1 V 1 = M 2 V 2 where "1" represents the concentrated conditions (i.e., stock solution molarity and volume) and "2" represents the diluted . Divide this answer (10.35 M mL) by the volume of the acid HCl (0.15 mL) MA = (MB VB)/VA = (0.500 M 20.70 mL)/0.15 mL = 0.690 M. The concentration is expressed as a number of moles per liter of solute. Because \(pK_a\) = log \(K_a\), we have \(pK_a = \log(1.9 \times 10^{11}) = 10.72\). Our chemical concentration sensors can handle the most difficult acids, including hydrofluoric acid and oleum. If you're getting enough nitrates in your diet, you can boost nitric oxide in other ways, as well. The same goes for strong bases, except the negative logarithm gives you the pOH as opposed to the pH. In fact, a 0.1 M aqueous solution of any strong acid actually contains 0.1 M \(H_3O^+\), regardless of the identity of the strong acid. The experiment has possibilities for use as an assessed practical. Similarly, Equation \(\ref{16.5.10}\), which expresses the relationship between \(K_a\) and \(K_b\), can be written in logarithmic form as follows: The values of \(pK_a\) and \(pK_b\) are given for several common acids and bases in Tables \(\PageIndex{1}\) and \(\PageIndex{2}\), respectively, and a more extensive set of data is provided in Tables E1 and E2. Weight ratio concentration: Concentration indirectly expressed by weight ratio at which solid reagent is dissolved. 16.4: Acid Strength and the Acid Dissociation Constant (Ka) is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. The ability of a substance to eat through other materials or damage skin is more of a function of the properties of that acid, as well as its concentration. When the color change becomes slow, start adding the titrant dropwise. If we are given any one of these four quantities for an acid or a base (\(K_a\), \(pK_a\), \(K_b\), or \(pK_b\)), we can calculate the other three. All the other mixtures show a weight loss not exceeding 2% even after 56 days immersion. For example, adding 50 mL of ethanol to 50 mL of water will result in a total volume that is less than 100 mL. An important note is in order. It is used in JIS and others. 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. The constants \(K_a\) and \(K_b\) are related as shown in Equation \(\ref{16.5.10}\). Therefore the solution of benzoic acid will have a lower pH. If the acid or base conducts electricity weakly, it is a weak acid or base. One method is to use a solvent such as anhydrous acetic acid. The \(pK_a\) and \(pK_b\) for an acid and its conjugate base are related as shown in Equations \(\ref{16.5.15}\) and \(\ref{16.5.16}\). An acid or base which strongly conducts electricity contains a large number of ions and is called a strong acid or base and an acid or base which conducts electricity only weakly contains only a few ions and is called a weak acid or base. A typical plant of 1,000t.d -1 capacity has been selected for further description but all data These terms refer to the ratio of reactants to products in equilibrium when the acid or base reacts with water. Chemistry questions and answers. For 60% nitric acid use 0.76 as the factor. PH is based on the concentration of the hydronium ion (H3O+) which is a product of the reaction of acid and water. Prepare Aqua Regia Solution. Like any other conjugate acidbase pair, the strengths of the conjugate acids and bases are related by \(pK_a\) + \(pK_b\) = pKw. The relative order of acid strengths and approximate \(K_a\) and \(pK_a\) values for the strong acids at the top of Table \(\PageIndex{1}\) were determined using measurements like this and different nonaqueous solvents. For any conjugate acidbase pair, \(K_aK_b = K_w\). Although \(K_a\) for \(HI\) is about 108 greater than \(K_a\) for \(HNO_3\), the reaction of either \(HI\) or \(HNO_3\) with water gives an essentially stoichiometric solution of \(H_3O^+\) and I or \(NO_3^\). The odd H3PO3 Therefore, to figure out the % w/v of a 100ml solution that is made up of 65g nitric acid, we would divide 65g by 100ml and then multiply the answer by 100. For example, a 70 % (v/v) solution of ethanol can be prepared by dissolving 70 mL of 100% (i.e., 200 proof) ethanol in a total solution volume of 100 mL. Conversely, the conjugate bases of these strong acids are weaker bases than water. pH Calculator. Dilutions to Make a 1 Molar Solution 1. Acid and Base pH Indicators - pH range vs. color change for acid and base indicators - together with pKa and structures of the indicators. It is a strong monobasic acid and a powerful oxidizing agent. The equilibrium will therefore lie to the right, favoring the formation of the weaker acidbase pair: \[ \underset{\text{stronger acid}}{CH_3CH_2CO_2H_{(aq)}} + \underset{\text{stronger base}}{CN^-_{(aq)}} \ce{<=>>} \underset{\text{weaker base}}{CH_3CH_2CO^-_{2(aq)}} +\underset{\text{weaker acid}} {HCN_{(aq)}} \nonumber \], A Video Discussing Polyprotic Acids: Polyprotic Acids [youtu.be]. (In fact, the \(pK_a\) of propionic acid is 4.87, compared to 4.76 for acetic acid, which makes propionic acid a slightly weaker acid than acetic acid.) Calculations are based on hydrochemistry program PhreeqC. The equilibrium will therefore lie to the right, favoring the formation of the weaker acidbase pair: \[ \underset{\text{stronger acid}}{NH^+_{4(aq)}} + \underset{\text{stronger base}}{PO^{3-}_{4(aq)}} \ce{<=>>} \underset{\text{weaker base}}{NH_{3(aq)}} +\underset{\text{weaker acid}} {HPO^{2-}_{4(aq)}} \nonumber \]. Garlic. of the nitric acid of the given purity (65%) and add to distilled water in a standard flask (1L) up to mark . That means number of moles of sulfuric acid is half that of number of moles of sodium hydroxide used. Consequently, the proton-transfer equilibria for these strong acids lie far to the right, and adding any of the common strong acids to water results in an essentially stoichiometric reaction of the acid with water to form a solution of the \(H_3O^+\) ion and the conjugate base of the acid. There are some exceptions, such as carbon monoxide, CO, nitrous oxide, N2O, and nitric oxide, NO. \(K_a = 1.4 \times 10^{4}\) for lactic acid; \(K_b = 7.2 \times 10^{11}\) for the lactate ion, \(NH^+_{4(aq)}+PO^{3}_{4(aq)} \rightleftharpoons NH_{3(aq)}+HPO^{2}_{4(aq)}\), \(CH_3CH_2CO_2H_{(aq)}+CN^_{(aq)} \rightleftharpoons CH_3CH_2CO^_{2(aq)}+HCN_{(aq)}\), \(H_2O_{(l)}+HS^_{(aq)} \rightleftharpoons OH^_{(aq)}+H_2S_{(aq)}\), \(HCO^_{2(aq)}+HSO^_{4(aq)} \rightleftharpoons HCO_2H_{(aq)}+SO^{2}_{4(aq)}\), Acid ionization constant: \[K_a=\dfrac{[H_3O^+][A^]}{[HA]} \nonumber \], Base ionization constant: \[K_b= \dfrac{[BH^+][OH^]}{[B]} \nonumber \], Relationship between \(K_a\) and \(K_b\) of a conjugate acidbase pair: \[K_aK_b = K_w \nonumber \], Definition of \(pK_a\): \[pKa = \log_{10}K_a \nonumber \] \[K_a=10^{pK_a} \nonumber \], Definition of \(pK_b\): \[pK_b = \log_{10}K_b \nonumber \] \[K_b=10^{pK_b} \nonumber \], Relationship between \(pK_a\) and \(pK_b\) of a conjugate acidbase pair: \[pK_a + pK_b = pK_w \nonumber \] \[pK_a + pK_b = 14.00 \; \text{at 25C} \nonumber \]. Acid & Base Molarity & Normality Calculator . The H+ concentration is 1.0 10-4/(0.049 L + 0.050 L) = 1.0 10-4/(0.099 L) = 1.00 10-3 M. As pH = -log[H+], pH will be 3. The leveling effect applies to solutions of strong bases as well: In aqueous solution, any base stronger than OH is leveled to the strength of OH because OH is the strongest base that can exist in equilibrium with water. Acidbase reactions always contain two conjugate acidbase pairs. Some chemists and analysts prefer to work in acid concentration units of Molarity (moles/liter). When examining the equation for each of the percent solutions above, it is very important to note that in all cases the denominator refers to the solution mass or volume and not just the solvent mass or volume. Thus propionic acid should be a significantly stronger acid than \(HCN\). Example: Sulfuric acid (1 + 2) Sulfuric acid is shown diluted with 2 volumes of water. The magnitude of the equilibrium constant for an ionization reaction can be used to determine the relative strengths of acids and bases. Once the color change is permanent, stop adding the solution. No acid stronger than \(H_3O^+\) and no base stronger than \(OH^\) can exist in aqueous solution, leading to the phenomenon known as the leveling effect. Like all equilibrium constants, acidbase ionization constants are actually measured in terms of the activities of \(H^+\) or \(OH^\), thus making them unitless. Thus acid strength decreases with the loss of subsequent protons, and, correspondingly, the \(pK_a\) increases. Equilibrium always favors the formation of the weaker acidbase pair. University of Maiduguri. HSO 4-Hydrogen sulfate ion. In fact, all six of the common strong acids that we first encountered in Chapter 4 have \(pK_a\) values less than zero, which means that they have a greater tendency to lose a proton than does the \(H_3O^+\) ion. Volume/volume % solutes are also common, and are used when pure solutes in liquid form are used. + + Examples of strong acids are hydrochloric acid (), perchloric acid (), nitric acid and sulfuric acid ().. A weak acid is only partially dissociated, with . Therefore, when preparing volume/volume percent solutions, it is always better to dissolve the solute in solvent and then add additional solvent to bring the total. Legal. Hence this equilibrium also lies to the left: \[H_2O_{(l)} + NH_{3(aq)} \ce{ <<=>} NH^+_{4(aq)} + OH^-_{(aq)} \nonumber \]. Upon distillation, nitric acid in its pure form begins to boil at 78.2C and becomes solid when it is well cooled. The word titration comes from the French word tiltre, originally meaning the "proportion of gold or silver in coins," later meaning the "concentration of a substance in a given sample." Smaller values of \(pK_a\) correspond to larger acid ionization constants and hence stronger acids. The most accurate way to determine pH is through use of a calibrated pH meter and electrode. Although exact determination is impossible, titration is a valuable tool for finding the molarity. Each percent solution is appropriate for a number of different applications. The table below gives the density (kg/L) and the corresponding The hydrogen ion concentration decreases by a factor of 10, so the pH increases by 1 . The addition of a base removes the free fatty acids present, which can then be used to produce soap. Acid & Base Molarity & Normality Calculator. Acid-base titration calculations help you identify a solution's properties (such as pH) during an experiment or what an unknown solution is when doing fieldwork. A conjugate acid, within the Brnsted-Lowry acid-base theory, is a chemical compound formed when an acid donates a proton (H +) to a basein other words, it is a base with a hydrogen ion added to it, as in the reverse reaction it loses a hydrogen ion. H 2 O. \[HA_{(aq)} \rightleftharpoons H^+_{(aq)}+A^_{(aq)} \label{16.5.3} \]. 2. Formula: Density = weight / volume or Volume = weight / density or Volume of 100 gram of Nitric acid: 100/1.413 = 70.771 ml Note: 70% (w/w) Nitric acid means that 100 g of Nitric acid contain 70 g of HNO3. HNO 3. Input a temperature and density within the range of the table to calculate for Two species that differ by only a proton constitute a conjugate acidbase pair. Predict whether the equilibrium for each reaction lies to the left or the right as written. No other units of measurement are included in this standard. Conversely, smaller values of \(pK_b\) correspond to larger base ionization constants and hence stronger bases. where each bracketed term represents the concentration of that substance in solution. Check out 19 similar mixtures and solutions calculators , Table of common acids and bases and their strengths. If the acid or base conducts electricity strongly, it is a strong acid or base. Belmont: Thomson Higher Education, 2008. The conjugate base of a strong acid is a weak base and vice versa. The usual molar ratio between concentrated hydrochloric acid and concentrated nitric acid is HCl:HNO 3 of 3:1. Answer (1 of 3): If you have a solution of nitric acid of unknown concentration, there are a few ways to determine that. Legal. In a situation like this, the best approach is to look for a similar compound whose acidbase properties are listed. For example, propionic acid and acetic acid are identical except for the groups attached to the carbon atom of the carboxylic acid (\(\ce{CH_2CH_3}\) versus \(\ce{CH_3}\)), so we might expect the two compounds to have similar acidbase properties. Asked for: corresponding \(K_b\) and \(pK_b\), \(K_a\) and \(pK_a\). Like all equilibrium constants, acid-base ionization constants are actually measured in terms of the activities of H + or OH , thus making them unitless. * A base that has a very high pH (10-14) are known as . Oxalic acid. Large. Calculate the molality of nitric acid solution a) 29.0 b) 11.0 c) 43.2 d) 16.0 Question 8 (10 points) A concentrated aqueous solution of nitric acid (HNO3) has a density . The table below gives the density (kg/L) and the . You will notice in Table \(\PageIndex{1}\) that acids like \(H_2SO_4\) and \(HNO_3\) lie above the hydronium ion, meaning that they have \(pK_a\) values less than zero and are stronger acids than the \(H_3O^+\) ion. Butyric acid is responsible for the foul smell of rancid butter. My second question is: let's a calculate number of grams of zinc to react to produce 29.1 grams of f h, 4. The values of \(K_a\) for a number of common acids are given in Table \(\PageIndex{1}\). This tells us that there is a nitric acid solution of 65% w/v. Thus, solution mass is the combined mass of solute and solvent, and solution volume is the combined volume of solute . density of nitric acid is equal to 1 512.9 kg/m; at 20C (68F or 293.15K) at standard atmospheric pressure . Perchloric acid. Nitric acid is highly corrosive. Did you know molecules can have a pH at which they are free of a negative charge, and that is what our isoelectric point calculator determines? The conjugate base of HNO 3 is NO 3- and conjugate acid is NO 2+. The density of concentrated nitric acid is 1.42 g/mL. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. For an aqueous solution of a weak acid, the dissociation constant is called the acid ionization constant (\(K_a\)). The larger the \(K_a\), the stronger the acid and the higher the \(H^+\) concentration at equilibrium. Nitric acid decomposes into water, nitrogen dioxide, and oxygen, forming a brownish yellow solution. The strength of an acid or base can be either strong or weak. Usually, we are ultimately interested in the number of moles of acid used. The Ka value of ammonium (NH4+) is 5.6*10-10, the Kb value of ammonia (NH3) 1.8*10-5, is ammonium more strongly acidic than ammonia is basic? Nitric acid or citric acid (CitriSurf) immersion bath to fully dissolve any free irons and sulfides and expedite the formation of passive film or oxide layer Water rinse - Commonly with DI water in high-precision industries Second water rinse - Commonly with DI Water in high-precision industries Dry parts * An acid that has a very low pH (0-4) are known as Strong acids. In Imperial or US customary measurement system, the density is equal to 94.44726 pound per cubic foot [lb/ft], or 0. . At the equivalence point, the number of moles of titrant added equals the number of moles of an analyte according to the reaction stoichiometry. Because it is 100% ionized or completely dissociates ions in an aqueous solution. Strong acids have mostly ions in solution, therefore the bonds holding H and A together must be weak. Oxtboy, Gillis, Campion, David W., H.P., Alan. Initial Data. But when mixing a chemical solution, you can determine the expected pH using . As you may know, when an acid or a base dissolves in water, their H+\small\text{H}^+H+ and OH\small\text{OH}^-OH ions respectively dissociate, shifting the natural self-ionization equilibrium of water (2H2OH3O++OH\small2\text{H}_2\text{O}\rightleftharpoons\text{H}_3\text{O}^+ + \text{OH}^-2H2OH3O++OH), making the solution more acidic or more basic. Acid. Here's the titration curve of NaOH\small\text{NaOH}NaOH neutralising HCl\small\text{HCl}HCl. concentration or input concentration to calculate for density. 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. concentration (% weight) of Nitric Acid (HNO3) solutions in water at different temperatures in degrees centigrade (C). H 2 SO 4. Note the endpoint on the burette. Nitric acid is the most commonly used wash for scale removal and pH stabilization after a caustic wash. At a typical concentration of 0.5%, it can be used effectively at lower temperatures than caustic solutions, requiring less heating. All-In-One Science Solution. PubChem . HCL, 37% - 12.2 Molar Strength = 36.5-38%, Density = 1.185, Molecular Weight = 36.5 . Calculate \(K_a\) for lactic acid and \(pK_b\) and \(K_b\) for the lactate ion. A 50.0 mL sample of 0.200 M sodium hydroxide is titrated with 0.200 M nitric acid. Mass Molarity Calculator. pH is 3.00. One specication for white fuming nitric acid is that it has a maximum of 2% . Name. Salts such as \(K_2O\), \(NaOCH_3\) (sodium methoxide), and \(NaNH_2\) (sodamide, or sodium amide), whose anions are the conjugate bases of species that would lie below water in Table \(\PageIndex{2}\), are all strong bases that react essentially completely (and often violently) with water, accepting a proton to give a solution of \(OH^\) and the corresponding cation: \[K_2O_{(s)}+H_2O_{(l)} \rightarrow 2OH^_{(aq)}+2K^+_{(aq)} \label{16.5.18} \], \[NaOCH_{3(s)}+H_2O_{(l)} \rightarrow OH^_{(aq)}+Na^+_{(aq)}+CH_3OH_{(aq)} \label{16.5.19} \], \[NaNH_{2(s)}+H_2O_{(l)} \rightarrow OH^_{(aq)}+Na^+_{(aq)}+NH_{3(aq)} \label{16.5.20} \]. Find the normality of 0.321 g sodium carbonate in a 250 mL solution. The curve around the equivalence point will be relatively steep and smooth when working with a strong acid and a strong . The magnitude of the equilibrium constant for an ionization reaction can be used to determine the relative strengths of acids and bases. This test method is suitable for concentrations between approximately 50 and 70 %, calculated as nitric acid. So, in 20 ml of acidic solution 1.80 x 10-3 equivalent of acids. If 13.7 mL of hydrochloric acid solution is taken, then [13.7 mL x (1.18 g/mL) = 16.2 g is the mass of the hydrochloric acid solution. Rounded to nearest 0.5ml. 11.3 Calculate the assay as percent nitric acid as follows: nitric acid, % by weight 5 VN 3 6301 W (2) where: V = corrected NaOH solution required for titration of the sample, mL, N = normality of the NaOH solution corrected for tempera-ture at time of titration, and W = sample used, g. 12. home; aqion; about; Add 1, 2 or 3 reactants to water: . The titration curve can also determine whether the solution is a strong or weak acid/base. Consider \(H_2SO_4\), for example: \[HSO^_{4 (aq)} \ce{ <=>>} SO^{2}_{4(aq)}+H^+_{(aq)} \;\;\; pK_a=-2 \nonumber \]. Example: Sodium chloride (1 + 19) Dissolved in 19 weight of water with respect to 1 of NaCl. Strong acid examples are hydrochloric acid (HCl), perchloric . HNO 3, 70% - 15.8 Molar Strength = 69-70%, Density = 1.42, Molecular Weight = 63.01 1 liter = 1420 gm = 994 gm HNO 3 (@70%) = 15.8 moles = 15.8 Molar The stronger an acid is, the lower the pH it will produce in solution. All acids have a conjugate base that forms when they react with water, and similarly, all bases have a conjugate acid that reacts when they form with water.1 You can judge the relative strength of a conjugate by the \(K_a\) or \(K_b\) value of the substance because \(K_a \times K_b\) is equal to the ionization constant of water, Kw which is equal to \(1 \times 10^{-14}\) at room temperature. The indicator will change colour when this 1:11:11:1 ratio (governed by its titration curve) is achieved. The difference between this and the starting point gives you the volume, and from this, you can calculate the molarity of the analyte using the equation above. Given that this is a diprotic acid, which H atoms are lost as H+ ions? Molarity HNO3 (Nitric acid) is a strong acid. Because percent solutions can be expressed in three different ways, it is imperative that the type of percent solution be explicitly stated. For example, when using a strong acid and a weak base, an indicator that changes at a low pH is needed, such as methyl orange (3.1-4.4). Because of the use of negative logarithms, smaller values of \(pK_a\) correspond to larger acid ionization constants and hence stronger acids. Name. Substituting the \(pK_a\) and solving for the \(pK_b\). To prepare 2.5M or 2.5N, you just need to find the vol. Acid and Base Strength is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. are hidden by default. CALCULATOR OPTIONS Acid & Base Molarity & Normality Calculator. 5.4 * 10-2. Titrations are commonly used to determine the concentration of acid rain that falls. Because the stronger acid forms the weaker conjugate base, we predict that cyanide will be a stronger base than propionate. Exposure to nitric acid can cause irritation to the eyes, skin, and mucous membrane; it can also cause delayed pulmonary edema, pneumonitis, bronchitis, and dental erosion. ClO 4 . pH Calculator. This calculator calculates for concentration or density values that are between those given in the table below by a High-strength acid (90 percent or greater nitric acid) can be produced from dehydrating . A standard acid-base titration uses a titrant of known concentration to titrate a tank of unknown concentration. Enter appropriate values in all cells except the one you wish to calculate. 1. The polarity of the H-A bond affects its acid strength. The percent dissociation of an acid or base is mathematically indicated by the acid ionization constant (Ka) or the base ionization constant (Kb)1. Hence, the acid is strong. Place on a white tile under the burette to better observe the color. To see them, click the 'Advanced mode' button at the bottom of the calculator. When examining the equation for each of the percent solutions above, it is very important to note that in all cases the denominator refers to the, A final note is necessary when considering volume/volume % solutions. The values of Ka for a number of common acids are given in Table 16.4.1. The equivalence point will occur at a pH within the pH range of the stronger solution, i.e., for a strong acid and a weak base, the pH will be <7. The table was taken from "Perry's Chemical Engineers' Handbook" by Robert H. Perry, Don Green, Sixth Edition. The base ionization constant \(K_b\) of dimethylamine (\((CH_3)_2NH\)) is \(5.4 \times 10^{4}\) at 25C. Total volume of solution including acid/base (liters): Calculate . In contrast, in the second reaction, appreciable quantities of both \(HSO_4^\) and \(SO_4^{2}\) are present at equilibrium. In presence of strong acids like sulfuric acid, HNO 3 acts as the base because it has to accept the proton from the stronger acid. Our titration calculator will help you never have to ask "how do I calculate titrations?" The equilibrium constant for this dissociation is as follows: \[K=\dfrac{[H_3O^+][A^]}{[H_2O][HA]} \label{16.5.2} \]. Stephen Lower, Professor Emeritus (Simon Fraser U.) Find the pH of 0.5 grams of HCl disolved into 100 ml of water: 0.5 grams / (36.5 g/mole) = 0.014 moles HCl, HCl is a strong acid and completely dissociates in water, therefore the pH will be equal to the negative logarithm of the concentration of HCl. Sulfuric acid. Because the initial quantity given is \(K_b\) rather than \(pK_b\), we can use Equation \(\ref{16.5.10}\): \(K_aK_b = K_w\). Base. The instructor will test the conductivity of various solutions with a light bulb apparatus. Substituting the values of \(K_b\) and \(K_w\) at 25C and solving for \(K_a\), \[K_a(5.4 \times 10^{4})=1.01 \times 10^{14} \nonumber \]. Although, strong acids are more directly dangerous at lower concentrations a strong acid is not necessarily more dangerous than a weak one.