1 16.1 Acids and Bases: A Brief Review Arrhenius concept of acids and bases: an acid increases [H + ] and a base increases [OH ] Brønsted-Lowry Acids and Bases In the Brønsted-Lowry system, a Brønsted-Lowry acid is a species that donates H + and a Brønsted-Lowry base is a species that accepts H +. Therefore a Brønsted-Lowry base does not need to contain OH. NH 3 is a Brønsted-Lowry base but not an Arrhenius base. Consider NH 3 (aq) + H 2 O(l) NH 4 + (aq) + OH (aq): H 2 O donates a proton to ammonia. water is acting as an acid. NH 3 accepts a proton from water. ammonia is acting as a base. Amphoteric substances can behave as acids and bases. Thus water is an example of an amphoteric species. Conjugate Acid-Base Pairs Whatever is left of the acid after the proton is donated is called its conjugate base. Similarly, a conjugate acid is formed by adding a proton to the base
2 Sample Exercise 16.1 (p. 671) a) What is the conjugate base of each of the following acids: HClO 4 H 2 S PH 4 + HCO - 3? b) What is the conjugate acid of each of the following bases? CN - SO 4 2- H 2 O - HCO 3 Practice Exercise 16.1 Write the formula for the conjugate acid of each of the following: HSO 3 - F - PO 4 3- CO Sample Exercise 16.2 (p. 671) The hydrogen sulfite ion (HSO 3 - ) is amphoteric. a) Write an equation for the reaction of HSO 3 - with water, in which the ion acts as an acid. b) Write an equation for the reaction of HSO 3 - with water, in which the ion acts as a base. In both cases identify the conjugate acid-base pairs. Practice Exercise 16.2 When lithium oxide (Li 2 O) is dissolved in water, the solution turns basic from the reaction of the oxide ion (O 2- ) with water. Write the reaction that occurs, and identify the conjugate acid-base pairs
3 Relative Strengths of Acids and Bases The stronger an acid is, the weaker its conjugate base will be. 1. Strong acids completely transfer their protons to water. 2. Weak acids only partially dissociate in aqueous solution. 3. Substances with negligible acidity do not transfer a proton to water. In every acid-base reaction, the position of the equilibrium favors the transfer of a proton from the stronger acid to the stronger base. H + is the strongest acid that can exist in equilibrium in aqueous solution. OH is the strongest base that can exist in equilibrium in aqueous solution. Sample Exercise 16.3 (p. 673) For the following proton-transfer reaction, use the above figure to predict whether the equilibrium lies predominantly to the left or to the right HSO 4 - (aq) + CO 3 2- (aq) SO 4 2- (aq) + HCO 3 - (aq) Practice Exercise 16.3 For each of the following reactions, use the above figure to predict whether the equilibrium lies predominantly to the left or to the right: a) HPO 4 2- (aq) + H 2 O (l) H 2 PO 4 - (aq) + OH - (aq) b) NH 4 + (aq) + OH - (aq) NH 3(aq) + H 2 O (l) - 3 -
4 16.3 The Autoionization of Water autoionization of water: 2H 2 O(l) H 3 O + (aq) + OH (aq) The Ion Product of Water equilibrium constant expression for the autoionization of water: Sample Exercise 16.4 (p. 674) 1.0 [ ] = K w = H O OH 3 Calculate the values of [H + ] and [OH - ] in a neutral solution at 25 o C. Practice Exercise 16.4 Indicate whether solutions with each of the following ion concentrations is neutral, acidic, or basic: a) [H + ] = 4 x 10-9 M b) [OH - ] = 1 x 10-7 M c) [OH - ] = 7 x M Sample Exercise 16.5 (p. 675) Calculate the concentration of H + (aq) in a) a solution in which [OH - ] is M (1.0 x M) b) a solution in which [OH - ] is 1.8 x 10-9 M (5.0 x 10-6 M) Assume T = 25 o C
5 Practice Exercise 16.5 Calculate the concentration of OH - (aq) in a solution in which a) [H + ] = 2 x 10-6 M b) [H + ] = [OH - ] c) [H + ] = 100 x [OH - ] 16.4 The ph Scale In most solutions [H + ] is quite small. We express the [H + ] in terms of ph: ph = log[h + ] = log[h 3 O + ] Sample Exercise 16.6 (p. 677) Calculate the ph values for the two solutions described in Sample Exercise (a) (12.00) b) (5.25) Practice Exercise 16.6 a) In a sample of lemon juice [H + ] is 3.8 x 10-4 M. What is the ph? (3.42) b) A commonly available window-cleaning solution has a [OH - ] of 1.9 x 10-6 M. What is the ph? (8.28) - 5 -
6 Sample Exercise 16.7 (p. 677) A sample of freshly pressed apple juice has a ph of Calculate [H + ]. (1.7 x 10-4 M) Practice Exercise 16.7 A solution formed by dissolving an antacid tablet has a ph of Calculate [H + ]. (6.6 x M) Other p Scales poh = log[oh ] log[h + ]+ ( log[oh ]) = ph + poh = logk w = Measuring ph ph meter. acid-base indicators
7 16.5 Strong Acids and Bases Strong Acids The most common strong acids are HCl, HBr, HI, HNO 3, HClO 3, HClO 4, and H 2 SO 4. MEMORIZE THESE! Strong acids are strong electrolytes and ionize completely in solution: HNO 3 (aq) + H 2 O(l) H 3 O + (aq) + NO 3 (aq) or HNO 3 (aq) H + (aq) + NO 3 (aq) In solution the strong acid is usually the only source of H +. Therefore, the ph of a solution of a monoprotic acid may usually be calculated directly from the initial molarity of the acid. Sample Exercise 16.8 (p. 680) What is the ph of a M solution of HClO 4? (1.40) Practice Exercise 16.8 An aqueous solution of HNO 3 has a ph of What is the concentration of the acid? ( M) Strong Bases The most common strong bases are ionic hydroxides of the alkali metals or the heavier alkaline earth metals (e.g., NaOH, KOH, and Ca(OH) 2 are all strong bases). MEMORIZE THESE Strong bases are strong electrolytes and dissociate completely in solution. For example: NaOH(aq) Na + (aq) + OH (aq) The poh (and thus the ph) of a strong base may be calculated using the initial molarity of the base. Not all bases contain the OH ion. Ionic metal oxides, hydrides, and nitrides are basic. The oxide, hydride and nitride ions are stronger bases than hydroxide. They are thus able to abstract a proton from water and generate OH
8 Sample Exercise 16.9 (p. 680) What is the ph of a) a M solution of NaOH? (12.45) b) a M solution of Ca(OH) 2? (11.34) Practice Exercise 16.9 What is the concentration of a solution of a) KOH for which the ph is 11.89? (7.8 x 10-3 M) b) Ca(OH) 2 for which the ph is 11.68? (2.4 x 10-3 M) 16.6 Weak Acids Weak acids are only partially ionized in aqueous solution: mixture of ions and un-ionized acid in solution. Therefore, weak acids are in equilibrium: HA(aq) + H 2 O(l) H 3 O + (aq) + A (aq) Or HA(aq) H + (aq) + A (aq) We can write an equilibrium constant expression for this dissociation: [ ][ ] + H 3O A Ka = or K [ HA] K a is called the acid-dissociation constant. + [ H ][ A ] [ HA] The larger the K a, the stronger the acid. K a is larger since there are more ions present at equilibrium relative to un-ionized molecules. If K a >> 1, then the acid is completely ionized and the acid is a strong acid. a = - 8 -
9 Calculating Ka from ph In order to find the value of K a, we need to know all of the equilibrium concentrations. The ph gives the equilibrium concentration of H +. Sample Exercise (p. 682) A student prepared a 0.10 M solution of formic acid (HCHO 2 ) and measured its ph. The ph at 25 o C was found to be Calculate the K a for formic acid at this temperature. (1.8 x 10-4 ) - 9 -
10 Practice Exercise Niacin, one of the B vitamins, has the following molecular structure: A M solution of niacin has a ph of What is the acid-dissociation constant, K a, for niacin? (1.5 x 10-5 ) Percent ionization is another method to assess acid strength. For the reaction % ionization = HA(aq) H + (aq) + A (aq) + [ H ] [ HA] equilibrium initial 100 The higher the percent ionization, the stronger the acid. However, we need to keep in mind that percent ionization of a weak acid decreases as the molarity of the solution increases
11 Sample Exercise (p. 684) A 0.10 M solution of formic acid (HCOOH) contains 4.2 x 10-3 M H + (aq). Calculate the percentage of the acid that is ionized. (4.2%) Practice Exercise A M solution of niacin has a ph of Calculate the percent ionization of the niacin. (2.7%)
12 Using K a to Calculate ph Using K a, we can calculate the concentration of H + (and hence the ph). 1. Write the balanced chemical equation clearly showing the equilibrium. CH 3 COOH (aq) H + (aq) + CH 3 COO - (aq) 2. Write the equilibrium expression. Look up the value for K a (in a table). K a = [H + ][ CH 3 COO - ] = 1.8 x 10-5 [CH 3 COOH] 3. Write down the initial and equilibrium concentrations for everything except pure water. We usually assume that the equilibrium concentration of H + is x. 4. Substitute into the equilibrium constant expression and solve. K a = 1.8 x 10-5 = [H + ][C 2 H 3 O - 2 ] = (x)(x) [HC 2 H 3 O 2 ] x Note that K a is very small (1.8 x 10-5 ) relative to [HC 2 H 3 O 2 ] (0.30 M). Keep this x x 2 = 1.8 x x Neglect x in the denominator since it is extremely small relative to (Use ballpark figure of 10 3 X difference for neglecting x in the denominator ) x 2 = (1.8 x 10-5 )(0.30) = 5.4 x 10-6 x 2 = (5.4 x 10-6 ) X = 2.3 x 10-3 M = [H + ] Check: Compare x with original [HC 2 H 3 O 2 ] of 0.30 M: 2.3 x 10-3 M x 100% = 0.77%, which is < 5% 0.30 M 5. Convert x ([H + ]) to ph. ph = - log (2.3 x 10-3 ) = 2.64 What do we do if we are faced with having to solve a quadratic equation in order to determine the value of x?
13 If x is <5% of the initial concentration, the assumption is probably a good one. If x>5% of the initial concentration, then it may be best to solve the quadratic equation or use successive approximations. Sample Exercise (p. 685) Calculate the ph of a 0.20 M solution of HCN. Refer to Table 16.2 for K a. (5.00) Practice Exercise The K a for niacin is 1.6 x What is the ph of a M solution of niacin? (3.41)
14 Sample Exercise (p. 687) Calculate the percentage of HF molecules ionized in a) a 0.10 M HF solution (7.9%) b) a M HF solution (23%) Practice Exercise In Practice Exercise 16.11, we found that the percent ionization of niacin (K a = 1.5 x 10-5 ) in a M solution is 2.7%. Calculate the percentage of niacin molecules ionized in a solution that is a) M (3.9%) b) a 1.0 x 10-3 M (12%)
15 Polyprotic Acids Polyprotic acids have more than one ionizable proton. The protons are removed in successive steps. e.g. H 2 SO 3 (sulfurous acid): H 2 SO 3 (aq) H + (aq) + HSO 3 (aq) K a1 = 1.7 x 10 2 HSO 3 (aq) H + (aq) + SO 3 2 (aq) K a2 = 6.4 x 10 8 It is always easier to remove the first proton in a polyprotic acid than the second: K a1 > K a2 > K a3, etc. The majority of the H + (aq) at equilibrium usually comes from the first ionization (i.e., the K a1 equilibrium). If the successive K a values differ by a factor of 0 3, we can usually get a good approximation of the ph of a solution of a polyprotic acid by only considering the first ionization. Sample Exercise (p. 689) The solubility of CO 2 in pure water at 25 o C and 0.1 atm pressure is M. the common practice is to assume that all of the dissolved CO 2 is in the form of carbonic acid (H 2 CO 3 ), which is produced by reaction between the CO 2 and H 2 O: CO 2(aq) + H 2 O (l) H 2 CO 3(aq) What is the ph of a M solution of H 2 CO 3? (4.40)
16 Practice Exercise (p. 690) a) Calculate the ph of a M solution of oxalic acid (H 2 C 2 O 4 ). (see Table 16.3 for K a1 and K a2 ). b) Calculate the concentration of oxalate ion [C 2 O 2-4 ]. (ph = 1.80; [C 2 O 2-4 ] = 6.4 x 10-5 M)
17 16.7 Weak Bases Weak bases remove protons from substances. There is an equilibrium between the base and the resulting ions: Weak base + H 2 O(l) conjugate acid + OH (aq) Example: NH 3 (aq) + H 2 O(l) NH 4 + (aq) + OH (aq). The base-dissociation constant, K b, is defined as The larger K b, the stronger the base. K b = + [ NH ][ OH ] 4 [ NH 3 ] Sample Problem (p. 691) Calculate the concentration of OH - in a 0.15M solution of NH 3. (1.6 x 10-3 M)
18 Practice Problem Which of the following compounds should produce the highest ph as a 0.05 M solution: pyridine, methylamine, or nitrous acid? (methylamine) Types of Weak Bases Weak bases generally fall into one of two categories. 1. Neutral substances with a lone pair of electrons that can accept protons. Most neutral weak bases contain nitrogen. Amines are related to ammonia and have one or more N H bonds replaced with N C bonds (e.g., CH 3 NH 2 is methylamine). Like NH 3, amines can abstract a proton from a water molecule by forming an additional N-H bond, as shown in this figure for methylamine. 2. Anions of weak acids are also weak bases. e.g.: ClO is the conjugate base of HClO (weak acid): ClO (aq) + H 2 O(l) HClO(aq) + OH (aq) K b = 3.3 x 10 7 Sample Exercise (p. 692) A solution made by adding solid sodium hypochlorite (NaClO) to enough water to make 2.00 L of solution has a ph of How many moles of NaClO were added to the water? (See info immediately above.) (0.60 mol)
19 Practice Exercise A solution of NH 3 in water has a ph of What is the molarity of the solution? (0.12 M)
20 16.8 Relationship Between K a and K b Consider the following equilibria: NH 4 + (aq) NH 3 (aq) + H + (aq) NH 3 (aq) + H 2 O(l) NH 4 + (aq) + OH (aq) We can write equilibrium expressions for these reactions: K a [NH3 ][H ] = + [NH ] 4 If we add these equations together: NH 4 + (aq) NH 3 (aq) + H + (aq) NH 3 (aq) + H 2 O(l) NH 4 + (aq) + OH (aq) The net reaction is the autoionization of water. H 2 O(l) H + (aq) + OH (aq) + [NH 4 ][OH ] = [NH ] Recall that: K w = [H + ][OH ] K a x K b = K w Or pk a + pk b = pk w = (at 25 o C) Thus, the larger K a (and the smaller pk a), the smaller K b (and the larger pk b ). The stronger the acid, the weaker its conjugate base and vice versa. K b Sample Exercise (p. 695) Calculate a) the base-dissociation constant, K b, for the fluoride ion (F - ); (1.5 x ) b) the acid-dissociation constant, K a, for the ammonium ion (NH 4 + ). (5.6 x )
21 Practice Exercise a) Which of the following anions has the largest base-dissociation constant: NO 2 -, PO 4 3-, or N 3 -? (PO 4 3-, K b = 2.4 x 10-2 ) b) The base quinoline has the following structure: Its conjugate acid is listed in handbooks as having a pk a of What is the base-dissociation constant for quinoline? (7.9 x )
22 16.9 Acid-Base Properties of Salt Solutions Acid-base properties of salts are a consequence of the reactions of their ions in solution. An Anion s Ability to React with Water Anions from weak acids are basic: They will cause an increase in ph. Anions from strong acids are neutral. They do not cause a change in ph. Anions with ionizable protons (e.g., HSO 4 ) are amphiprotic. They are capable of acting as an acid or a base. If K a > K b, the anion tends to decrease the ph. If K b > K a, the anion tends to increase the ph. A Cation s Ability to React with Water Polyatomic cations that have 1 or more ionizable protons are conjugate acids of weak bases decrease ph. Metal cations of Group 1A and heavy alkaline earth metals are cations of strong bases and do not alter ph. Other metal ions can cause a decrease in ph. Combined Effect of Cation and Anion in Solution The ph of a solution may be qualitatively predicted using the following guidelines: Salts derived from a strong acid and a strong base are neutral. Examples are NaCl and Ca(NO 3 ) 2. Salts derived from a strong base and a weak acid are basic. Examples are NaClO and Ba(C 2 H 3 O 2 ) 2. Salts derived from a weak base and a strong acid are acidic. An example is NH 4 Cl. Salts derived from a weak acid and a weak base can be either acidic or basic. Equilibrium rules apply! We need to compare K a and K b for hydrolysis of the anion and the cation. For example, consider NH 4 CN. Both ions undergo significant hydrolysis. Is the salt solution acidic or basic? The K a of NH 4 + is smaller than the K b of CN, so the solution should be basic
23 Sample Exercise (p. 698) Determine whether aqueous solutions of each of the following salts will be acidic, basic, or neutral: a) Ba(CH 3 COO) 2, b) NH 4 Cl c) CH 3 NH 3 Br d) KNO 3 e) Al(ClO 4 ) 3 Practice Exercise In each of the following, indicate which salt in each of the following pairs will form the more acidic (or less basic) M solution: a) NaNO 3 or Fe(NO 3 ) 3 b) KBr, or KBrO c) CH 3 NH 3 Cl or BaCl 2 d) NH 4 NO 2 or NH 4 NO
24 Sample Exercise (p. 698) Predict whether the salt Na 2 HPO 4 will form an acidic or a basic solution on dissolving in water. (basic) Practice Exercise Predict whether the dipotassium salt of citric acid (K 2 HC 6 H 5 O 7 ) will form an acidic or basic solution in water. (see Table 16.3 for data) (acidic)
25 16.10 Acid-Base Behavior and Chemical Structure Factors That Affect Acid Strength The H X bond must be polar with H δ+ and X δ-. In ionic hydrides, the bond polarity is reversed. The H X bond is polar with H δ- and X δ+ : the substance is a base. Other factors important in determining acid strength include: The strength of the bond: the H X bond must be weak enough to be broken. The stability of the conjugate base, X : the greater the stability of the conjugate base, the more acidic the molecule. Binary Acids Group trends: The H X bond strength tends to decrease as the element X increases in size. Acid strength increases down a group; base strength decreases down a group. Period trends: Acid strength increases and base strength decreases from left to right across a period as the electronegativity of X increases. Oxyacids Acids that contain OH groups (and often additional oxygen atoms) bound to the central atom All oxyacids have the general structure Y O H, e.g. H 2 SO 4 The strength of the acid depends on Y and the atoms attached to Y. As the electronegativity of Y increases, so does the acidity of the substance. The bond polarity increases and the stability of the conjugate base (usually an anion) increases. Summary: For oxyacids with the same number of OH groups and the same number of oxygen atoms: Acid strength increases with increasing electronegativity of the central atom, Y. Example: HClO > HBrO > HIO For oxyacids with the same central atom, Y: Acid strength increases as the number of oxygen atoms attached to Y increases. Example: HClO 4 > HClO 3 > HClO 2 > HClO
26 Strength of oxyacids Sample Exercise (p.702) Arrange the compounds in each of the following series in order of increasing acid strength: a) AsH 3, HI, NaH, H 2 O; b) H 2 SO 4, H 2 SeO 3, H 2 SeO 4. Practice Exercise In each of the following pairs choose the compound that leads to the more acidic (or less basic) solution: a) HBr, HF; b) PH 3, H 2 S; c) HNO 2, HNO 3 ; d) H 2 SO 3, H 2 SeO 3. Carboxylic Acids There is a large class of acids that contain a COOH group (a carboxyl group). Acids that contain this group are called carboxylic acids: e.g. acetic acid, benzoic acid, formic acid
27 These molecules are acidic because: 1. The additional oxygen atom on the carboxyl group increases the polarity of the O H bond and stabilizes the conjugate base. 2. The conjugate base exhibits resonance. This gives it the ability to delocalize the negative charge over the carboxylate group, further increasing the stability of the conjugate base. The acid strength also increases as the number of electronegative groups in the acid increases. For example, acetic acid is much weaker than trichloroacetic acid. Comparison of Different Types of Acids and Bases Arrhenius (traditional) acids and bases (C19th) Acid: compound containing H that ionizes to yield H + in solution Base: compound containing OH that ionizes to yield OH - in solution (Note: does not describe acid/base behavior in solvents other than water) Note: Every Arrhenius acid/base is also a Brønsted-Lowry acid/base. Brønsted-Lowry Acids and Bases (1923) Acid: H + (proton) donor Base: H + (proton) acceptor NH 3 + H 2 O + NH 4 + OHammonia water ammonium ion hydroxide ion (B-L base) (B-L acid) (B-L acid) (B-L base) Note: Every Brønsted-Lowry acid/base is also a Lewis acid/base. Lewis Acids and Bases (1920 s) Acid: accepts pair of e- s Base: donates pair of e- s H+ + [:O:H]- H:O:H Lewis acid Lewis base
28 16.11 Lewis Acids and Bases A Brønsted-Lowry acid is a proton donor. Lewis: emphasize the shared electron pair. A Lewis acid is an electron pair acceptor. A Lewis base is an electron pair donor. Note: Lewis acids and bases do not need to contain protons. Therefore, the Lewis definition is the most general definition of acids and bases. What types of compounds can act as Lewis acids? Lewis acids generally have an incomplete octet (e.g., BF 3 ). For a substance to be a proton acceptor (a Brønsted- Lowry base), it must have an unshared pair of electrons for binding the proton. NH 3, for example, acts as a proton acceptor. Using Lewis structures, we can write the reaction between H + and NH 3 as shown in the firugre. Consider the reaction between NH 3 and BF 3. This reaction occurs because BF 3 has a vacant orbital in its valence shell. It therefore acts as an electron-pair acceptor (a Lewis acid) toward NH 3, which donates the electron pair. The curved arrow shows the donation of a pair of electrons from N to B to form a covalent bond. Transition-metal ions are generally Lewis acids. Lewis acids must have a vacant orbital (into which the electron pairs can be donated). Compounds with multiple bonds can act as Lewis acids. For example, consider the reaction: H 2 O(l) + CO 2 (g) H 2 CO 3 (aq) Water acts as the electron pair donor and carbon dioxide as the electron pair acceptor in this reaction. Overall, the water (Lewis base) has donated a pair of electrons to the CO 2 (Lewis acid)
29 Hydrolysis of Metal Ions The Lewis concept may be used to explain the acid properties of many metal ions. Metal ions are positively charged and attract water molecules (via the lone pairs on the oxygen atom of water). Hydrated metal ions act as acids, e.g. Fe(H 2 O) 3+ 6 (aq) Fe(H 2 O) 5 (OH) 2+ (aq) + H + (aq) K a = 2 x In general: The higher the charge, the stronger the M OH 2 interaction: K a values generally increase with increasing charge The smaller the metal ion, the more acidic the ion. K a values generally decrease with decreasing ionic radius Thus the ph of an aqueous solution increases as the size of the ion increases (e.g., Ca 2+ vs. Zn 2+ ) and as the charge increases (e.g., Na + vs. Ca 2+ and Zn 2+ vs. Al 3+ ). The Amphoteric Behavior of Amino Acids Amino acids: building blocks of proteins. Each contains a carboxyl group AND an amine group. Thus amino acids have both acidic and basic groups. They undergo a proton transfer in which the proton of the carboxyl is transferred to the basic nitrogen atom of the amine group A zwitterion or dipolar ion results. Sample Integrative Exercise 16 (p. 706) Phosphorous acid (H 3 PO 3 ) has the following Lewis structure: a) Explain why phosphorous acid is diprotic and not triprotic. b) A 25.0 ml sample of a solution of H 3 PO 3 is titrated with M NaOH. It requires 23.3 ml of NaOH to neutralize both acidic protons. What is the molarity of the H 3 PO 3 solution? c) This solution has a ph of Calculate the percent ionization and K a1 for H 3 PO 3, assuming that K a1 >>K a2. d) How does the osmotic pressure of a M solution of HCl compare qualitatively with that of a M solution of H 3 PO 3? Explain
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Chapter 14 1. Students will be able to define an acid and base in terms of both the Arrhenius and the Bronsted-Lowry definitions and provide examples of each (including examples that follow the Bronsted-Lowry
WEAK ACIDS AND BASES [MH5; Chapter 13] Recall that a strong acid or base is one which completely ionizes in water. HCR! H + + CR NaOH! Na + + OH The above equations fit the Arrhenius definition of acids
Announcements First Exam December 21---Christmas Break begins December 22. Silberberg Chapter 17-18, Skoog 2-7, 11-13 10-15 Conceptual Multiple choice questions that have little if any math 3-5 multiple
15.2 Acids Base Proton Transfer Dr. Fred Omega Garces Chemistry 201 Miramar College Important Notes: K a when H 3 O + is produced, K b when OH is produced 1 Acids Bases; Proton Transfer BrønstedLowry AcidsBases
1 Chapter 10 Acids, Bases, and Salts 2 Ch 10.1 Arrhenius Acid-Base Theory (also in Chapter Medley) Arrhenius Acids produce Arrhenius Bases produce H + in water OH - in water HCl hydrochloric acid KOH HNO
Chemistry, The Central Science, 10th edition Theodore L. Brown; H. Eugene LeMay, Jr.; Bruce E. Bursten Chapter 16 John D. Bookstaver St. Charles Community College St. Peters, MO 2006, Prentice Hall, Inc.
Chapter 16 AcidBase Equilibria Acids and bases are found in many common substances and are important in life processes. Group Work: Make a list of some common acids and bases. How do we know which is which?
Chapter 15 -Acids and Bases Principles of Chemistry A Molecular Approach, 1 st Ed. Nivaldo J. Tro Dr. Azra Ghumman Memorial University of Newfoundland The Nature of Acids and Bases Properties of Acids:
Chapter 15: Acids and Bases Essentials of General Chemistry Ebbing Gammon Ragsdale 2nd Edition Dr. Azra Ghumman Memorial University of Newfoundland 1 Acids and Bases 15.1 Arrhenius Concept of Acids and
Acids & Bases Mr. Matthew Totaro Legacy High School AP Chemistry 2012 Pearson Education, Inc. Properties of Acids Sour taste React with active metals i.e., Al, Zn, Fe, but not Cu, Ag, or Au corrosive 2
Class: Date: Chapter 13 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. In the Brønsted-Lowry model an acid is a. a proton donor. b. a proton
CHEM 1105 ACIDS AND BASES 1. Early Definitions Taste: Effect on Indicators: Neutralization: acids - sour; bases - bitter acids turn blue litmus red; bases turn red litmus blue phenolphthalein is colourless
CHAPTER 14 Acids and Bases 14.1 The Nature of Acids and Bases Arrhenius model Acid supplies H + to an aqueous solution Base supplies OH - to an aqueous solution Bronsted-Lowry model Acid is a proton (H
Chapter 16: Acid-Base and Solubility Equilibria: Reactions in Soil and Water Problems: 16.2-16.86 16.1 ACIDS AND BASES: THE BRØNSTED-LOWRY MODEL PROPERTIES OF ACIDS & BASES Acids produce hydrogen ions,
Water itself is a weak acid and weak base: Two water molecules react to form H 3 O + and OH - (but only slightly) H 2 O H 2 O H 3 O + OH - Autoionization of Water H 2 O (l) + H 2 O (l) H 3 O + (aq) + OH
Self Ionization of Water H 2 O H + + OH - Acids & Bases ph poh [H + ] [OH - ] Pure Water [H + ] = [OH - ], remember: [ ] means concentration 1 x 10 7 = 1 x 10 7 [H + ] > [OH - ], there is an acidic solution
Acids and Bases: Overview Common Uses of Acids and Bases Definitions of acids and bases Equilibria involving acids and bases Conjugate acid base pairs Autoionisation of water The p scale (ph, poh, pka,
(Hebden Unit it4 page 109 182) 182) We will cover the following topics: 1. Definition of Acids and Bases 2. Bronsted-Lowry Acids and Bases 2 1 Arrhenius Definition of Acids and Bases An acid is a substance
Reactions in Solution (Acids and Bases): Chapter 0 Chapter Outline Properties of Aqueous Solutions of Acids and Bases The Arrhenius Theory The Hydronium Ion (Hydrated Hydrogen Ion) The BrØnstedLowry Theory
Assessment Chapter Test A Chapter: Acids and Bases In the space provided, write the letter of the term or phrase that best completes each statement or best answers each question. 1. Which of the properties
Acids and Bases A logical place to go from our study of hydrogen compounds is Acids and Bases. In 1884 Arrhenius devised a theory to explain acid/base behavior. His theory states that Acids contain protons
Acids and Bases Bronsted Acidity Periodic trends Lewis Acidity Systematics of acids and bases Description of different acids and bases Proton transfer Electron pair sharing Acceptor and donator Description
Chapter 15 Acids and Bases Fu-Yin Hsu Stomach Acid and Heartburn The cells that line your stomach produce hydrochloric acid. To kill unwanted bacteria To help break down food To activate enzymes that break
Chapter 15: Acids and Bases I Chem 102 Dr. Curtis Acids and Bases Acids Sour taste vinegar Dissolve many metals Ability to neutralize bases Strong or Weak Bases Bitter taste caffeine, poisons from plants
CHAPTER 10 Reactions in Aqueous Solutions I: Acids, Bases & Salts 1. Properties of Aqueous Solutions of Acids & Bases 2. The Arrhenius Theory 3. The BrØnsted-Lowry Theory 4. The Lewis Theory 5. The Autoionization
C MgCO Al Al(OH) PX212CH1516 1. Which of the following reactions is not readily explained by the Arrhenius concept of acids and bases? A) HCl(g) + NH 3 (g) NH 4 Cl(s) B) HCl(aq) + NaOH(aq) NaCl(aq) + H
Lecture Presentation Chapter 15 Acids and Bases Sherril Soman Grand Valley State University Stomach Acid and Heartburn The cells that line your stomach produce hydrochloric acid. To kill unwanted bacteria
NOTES: Goals : To gain an understanding of : Properties of acids : Properties of bases : 1. The properties of acids and bases 2. ph and poh calculations 3. Definitions of acids and bases 4. Neutralization
Acids and Bases 10 Answers and Solutions to Text Problems 10.1 According to the Arrhenius theory: a. acids taste sour. b. acids neutralize bases. c. acids produce H 3 O + ions in water. d. potassium hydroxide
Acids, Bases, and Salts General Chemistry Ron Robertson I. Definitions The terms acid, base and salt are attempts to classify and organize reactions - these terms are used to model the behavior of species
DEFINITIONS OF AN ACID Who Theory: Acid= When LECTURE 3: ACIDS AND BASES Arrhenius increases H + 1880 s Brønsted proton donor 1923 Lowry proton donor 1923 Lewis electron-pair acceptor 1923 Svante August
Chapter 16 questions 1. Which of the following statements does not accurately describe a characteristic property of an Arrhenius acid? a) An Arrhenius acid is a substance that increases the concentration
1. For the equilibrium that exists in an aqueous solution of nitrous acid (HNO 2, a weak acid), the equilibrium constant expression is: a) K = [H+ ][NO 2 ] [HNO 2 ] b) K = [H+ ][N][O] 2 [HNO 2 ] c) K =
AP Chapter 15 & 16: Acid-Base Equilibria Name Warm-Ups (Show your work for credit) Date 1. Date 2. Date 3. Date 4. Date 5. Date 6. Date 7. Date 8. AP Chapter 15 & 16: Acid-Base Equilibria 2 Warm-Ups (Show
: Properties of Acids An acid is any substance that releases hydrogen ions, H +, into water. Blue litmus paper turns red in the presence of hydrogen ions. Blue litmus is used to test for acids. Acids have
Topic 5 5-1 Acid and Bases Acid and Bases 5-2 There are a number definitions for aicd and bases, depending on what is convenient to use in a particular situation: Arrhenius and Ostwald: Theory of electrolyte
Weak Acids Weak acids do not dissociated completely in aqueous solutions. They are somewhat stable molecules and therefore there is an equilibrium constant associated with their dissociation. It s called
WEAK ACIDS AND BASES [MH5; Chapter 13] Recall that a strong acid or base is one which completely ionizes in water... In contrast a weak acid or base is only partially ionized in aqueous solution... The
Chapter 16 Additional Practice Problems 1. Although pure NaOH and CaO have very different properties, their aqueous solutions possess many common properties. List some general properties of these solutions
Acids Acids and Bases Chapter 15 Topics: p scale, Strengths of Acids and Bases, Ionization Constants of Weak Acids and Bases; Properties of Salts ave a sour taste. Vinegar owes its taste to acetic acid.
Chemistry B2A Chapter 16 Acids and bases Arrhenius definitions: an acid is a substance that produces H 3 O + ions in aqueous solution. A base is a substance that produces OH - ions in aqueous solution.
AQUEOUS EQUILIBRIA Salts Hydrolysis The Common-Ion Effect Buffer Solutions Acid-Base Titrations Solubility Brown et al., Chapter 15, 569-606 CHEM120 Lecture Series One : 2011/01 SALTS AND HYDROLYSIS Recall:
Chapter 16 Acids and Bases Concept Check 16.1 Chemists in the seventeenth century discovered that the substance that gives red ants their irritating bite is an acid with the formula HCHO 2. They called
Chapter 17: Acids and Bases Bronsted-Lowry Devinition: An Acid is a proton (H + ; H 3 O + ) donor A Base is a proton (H + ; H 3 O + ) acceptor. Acids and Bases are discriminated by their strength. 17.1
Chapter 8 Acids and Bases Definitions Arrhenius definitions: An acid is a substance that produces H + (H 3 O + ) Ions in aqueous solution. A base is a substance that produces OH - ions in aqueous solution.
ph OF SOLUTIONS OBJECTIVES 1. To investigate the strengths of acids and bases 2. To examine the effect of concentration on the ph of a solution 3. To examine the effect of salt hydrolysis on ph 4. To determine
DO NOT WRITE ON QUIZ/EXAM - USE SCANTRON AND #2 PENCIL TEST # A Chapter 10 Test - AP Chemistry 2011/2012 Multiple Choice Identify the choice that best completes the statement or answers the question. 1.