# LESSON ASSIGNMENT. After completing this lesson, you should be able to: 9-2. Calculate buffers problems.

Save this PDF as:

Size: px
Start display at page:

Download "LESSON ASSIGNMENT. After completing this lesson, you should be able to: 9-2. Calculate buffers problems."

## Transcription

1 LESSON ASSIGNMENT LESSON 9 ph and Buffers. TEXT ASSIGNMENT Paragraphs 9-1 through LESSON OBJECTIVES After completing this lesson, you should be able to: 9-1. Calculate the ph and poh of a molar acid or base concentration Calculate buffers problems. SUGGESTION After studying the assignment, complete the exercises at the end of this lesson. These exercises will help you to achieve the lesson objectives. MD

2 LESSON 9 ph and BUFFERS Section I. INTRODUCTION 9-1. DISCUSSION a. The interaction of charged particles in which the total number of protons does not equal the number of electrons is responsible for many chemical reactions. These charged particles are called ions. A cation is an ion in which the protons are more numerous than the electrons (+ charge), and anions are ions in which the electrons outnumber the protons (- charge). These oppositely charged ions are attracted to each other and form bonds called ionic bonds. When ionically bound compounds are dissolved in a solvent, the ions separate. This separation is known as dissociation or ionization. The only way in which most ions can undergo chemical reaction is to be in this dissociated state. b. Three general types of ionic compounds exist: acids, bases, and salts. Simply and incompletely stated, acids are compounds that contribute hydrogen ions to a solution, bases are compounds that contribute hydroxide ions to the solution, and salts yield neither hydrogen nor hydroxide ions to the solution. The concentration of the hydrogen and hydroxide ions will determine the degree of acidity or alkalinity of a solution, and thus have an effect on the kinds of reactions and the speed of the reactions that will occur. It is important, therefore, to know the relative concentrations of the hydrogen and hydroxide ions in a solution. c. Before discussing hydrogen and hydroxide ion concentration further, it will be important to consider in greater detail the definition of an acid and a base. There are several definitions of the terms acid and base. We will examine two of the definitions that will aid you in further course work ARRHENIUS CONCEPT a. An acid is a substance that will produce hydrogen ions (H + ) in an aqueous solution, and a base is a substance that will produce hydroxide ion (OH - ) in an aqueous solution. It is important to note that hydrogen ions do not exist as such in an aqueous solution. Each hydrogen ion is associated with one molecule of water to produce a hydronium ion, H 3 O +. H + + H 2 O <====> H 3 O + MD

3 b. When hydrochloric acid (HCl), which exists in its pure state as a gas, is dissolved in water, the following reaction takes place: HCl + H 2 O <====> H 3 O + + Cl - c. The hydronium ion can easily react with other groups as a proton donor. The hydrogen ion itself is made up of one proton. NOTE: The terms hydronium ion, hydrogen ion, and proton donor may be used interchangeably. However, we will simply refer to the hydrogen ion in future course work, but you should understand that this actually implies the presence of the hydronium ion. d. One of the primary drawbacks of the Arrhenius concept is that it defines only aqueous solutions as acids and bases. Other theories allow for nonaqueous solutions. (1) Examples of Arrhenius acids. (a) HCl -- hydrochloric acid. (b) (c) H 2 SO 4 -- sulfuric acid. H 3 PO 4 -- phosphoric acid. (2) Examples of Arrhenius bases. (a) NaOH -- sodium hydroxide. (b) (c) Ca(OH) 2 -- calcium hydroxide. KOH -- potassium hydroxide BRONSTED-LOWRY THEORY The Bronsted-Lowry theory presents a broader definition of the terms acid and base. An acid is a proton donor and a base is a proton acceptor. Hydrochloric acid in solution is a Bronsted-Lowry use it forms hydrogen ions but because it is able to give up that hydrogen ion to another substance, such as to a molecule of water to form hydronium ions. For HCl, the difference between the two definitions seems minor. However, it becomes important when the solvent is not water. For example, when HCl reacts with NH 3 (ammonia), the proton is given up by the HCl and accepted by the NH 3, making the HCl an acid and NH 3 a base. HCl + NH 3 <====> NH Cl - acid base acid base MD

4 a. Examples of Bronsted-Lowry Acids. (1) NH ammonium ion. (2) HC 2 H 3 O 2 -- acetic acid. (3) H 2 CO 3 -- carbonic acid. b. Examples of Bronsted-Lowry Bases. (1) Cl - -- chloride ion. (2) NH 3 -- ammonia. (3) Fe(OH) 2 -- iron (II) hydroxide WEAK ACIDS/BASES VERSUS STRONG ACIDS/BASES a. As discussed previously, we stated that acids, bases, and salts are ionic compounds. Substances that break up into ions in solution are termed electrolytes because the solution has the ability to conduct electrical current. A strong electrolyte (acid or base) is a substance that exhibits a high degree of ionization, and a weak electrolyte is a substance that only partially ionizes. b. Hydrochloric acid (HCl), sulfuric acid (H 2 SO 4 ), and nitric acid (HNO 3 ) are strong acids because they exhibit a high degree of ionization in aqueous solutions. Hydrobromic acid (HBr), hydroiodic acid (HI), and perchloric acid (HClO 4 ) are also considered strong acids. All others are weak. c. The alkaline metal (Group IA, that is., lithium, sodium, potassium) hydroxides and the alkaline earth (Group IIA, for example, magnesium, calcium, and strontium) hydroxides are strong bases. Other bases are weak ones. form. d. Hydrogen (H + ) and hydroxide (OH - ) only affect ph or poh when in the ionized MD

5 Section II. DYNAMIC EQUILIBRIUM 9-5. DISCUSSION a. When an acid ionizes, an equilibrium is established between the unionized acid and its ions. This is indicated by double arrows or a doubled-headed arrow in an equation, showing that the two reactions occur simultaneously. HA is used to represent any acid made up of hydrogen and some anion. HA <====> H + + A - b. At the same time, the acid molecule is dissociating, a certain percentage of the ions are reassociating to reform the acid. When the acid is first placed in water, a high degree of dissociation occurs, and the rate of the forward reaction is greater. Gradually, as more ions are formed, the rate of the reverse reaction increases. Eventually, a state of equilibrium is reached in which molecules are being ionized and reassociated at a given rate. Equilibrium exists when the rates, not the number of molecules or concentrations, of the opposing reactions are equal. This is a dynamic, constant process and continues until a force is added to change this equilibrium. For example, if the temperature is increased, the rates of the reaction are increased, and a new equilibrium state is reached. Removing one of the ions or tying them up with another reaction will also shift the equilibrium LAW OF MASS ACTION a. Law. The law of mass action states that the rate of reaction is proportional to the product of the molar concentrations of the reactants. A + B <=====> C + D For this reaction, A and B are the reactants, and C and D are the products. The rate at which C and D are formed is proportional to the concentration of A and B. rate = K 1 [A] [B] where K 1 is a proportionality constant, and the brackets denote mol/l concentration of the enclosed substance. The rate for the reverse reaction is: rate = K 2 [C] [D] MD

6 b. Equilibrium Constant (K eq ). The constants K 1 and K 2 are different. The ratio of the constants is known as the equilibrium constant (K eq ), dissociation constant, or ionization constant. K 1 K eq = K 2 (1) At equilibrium, the rates of the forward and reverse reactions are equal. rate f = rate r rate f = K 1 [A] [B] rate r = K 2 [C] [D] K 1 [A] [B] = K 2 [C] [D] K 1 [C] [D] = K 2 [A] [B] K 1 = K eq K 2 (2) Simply, the ionization (equilibrium) constant is equal to the product of the mol/l concentrations of the products formed in the reaction divided by the product of the concentrations of the reactants. K b. (3) The equilibrium constant for an acid is called the K a and for a base the (4) K a and K b are determined for weak acids and bases only. If the K a or K b of a strong acid or base, respectively, were determined it would be an infinitely large number. (5) Values of equilibrium constants are interpreted as follows: (a) The constant indicates the strength of a weak electrolyte. respectively. (b) The smaller the value of the K a or K b, the weaker the acid or base MD

7 9-7. EXAMPLE What is the [H + ] of a mol/l solution of acetic acid if the K a for HC 2 H 3 O 2 is 1.75 X 10-5? Solution. Determine the equation for the dissociation of the weak acid. HC 2 H 3 O 2 <====> H + + C 2 H 3 O 2 - Write the equilibrium expression. [H + ][C 2 H 3 O 2 - ] K a = [HC 2 H 3 O 2 ] Substitute the given information, and solve for the unknown quantity. [H + ] [C 2 H 3 O 2 ] 1.75 X 10 5 mol/l = mol/l NOTE: Although the actual concentration of the acetic acid is less than mol/l after ionization, it is considered a negligible amount (less than 5%). In your future course work, the amount of ionized acid or base in this type of problem should be considered to be a negligible amount. Substitute the variable x for H + and C 2 H 3 O 2 - since for every dissociated molecule of HC 2 H 3 O 2, one hydrogen ion and one acetate radical are produced. x 2 = (1.75 X 10-5 mol/l) (0.100 mol/l) = 1.75 X 10-6 mol 2 /L 2 x = [H + ] = 1.32 X 10-3 mol/l NOTE: By convention, the equilibrium constants of weak electrolytes are written without units. However, they do have units. Section III. DISSOCIATION OF WATER 9-8. DISCUSSION a. Although water is not an electrolyte, its molecules do have a limited tendency to dissociate into H + and OH - ions. HOH <====> H + + OH - MD

8 b. It can be shown that the tendency of water to dissociate is given by: [H + ] [OH - ] K = [HOH] c. At 25º C, the value of K is 1.8 X ION PRODUCT OF WATER a. Since undissociated water is present in great excess, its concentration is virtually constant at 55.6 mol/l. NOTE: The gram molecular weight of water is 18.0; therefore, in 1.00 L (approximately 1000 grams), there are: (1000 g) (18.0 g/mol) = 55.6 Mol/L 1 L b. This constant value for the concentration of water can be incorporated into the dissociation constant to give a new constant, the ion product of water, or K w. [H + ] [OH - ] 1.8 X = [55.6] [H + ] [OH - ] = 1.0 X c. Therefore, in pure water: [H + ] = 1.0 X 10-7 mol/l [HO - ] = 1.0 X 10-7 mol/l K w = [H + ] [OH - ] = 1.0 X d. It is important to realize that the ion product of water, [H + ] and [OH - ], is constant for all aqueous solutions, even those that contain dissolved acids or bases. (1) If a large number of H + ions are added to pure water, the concentration of OH - ions must decrease in order that the product of [H + ] [OH - ] remains the same. (2) Conversely, if a large number of hydroxyl ions are added, the [H + ] will have to decrease. MD

9 Section IV. ph and poh CONCEPT OF ph Pure water contains an equal concentration of hydrogen and hydroxide ion. Thus, it is a neutral substance, neither acidic nor basic. If a solution has an excess of hydrogen ions, the solution will be acidic. If a solution has an excess of hydroxide ions, the solution will be alkaline. It is customary to use the hydrogen ion concentration (ph) as a measure of the acidity or alkalinity of a solution. ph is a unit of concentration that allows the technician to work with very dilute concentrations of hydrogen and hydroxide ion in a convenient form. This scale permits the representation of the enormous range of the possible [H + ] concentrations from a 1.0 mol/l [H + ] to a 1.0 X mol/l [H + ] APPLICATION OF CONCEPT OF ph The notation p denotes "negative log of." Logarithms are discussed in lesson 1, and there is a four-place logarithm table in Appendix B. ph is mathematically defined as: -log [H + ] or log 1/[H + ] a. Example 1. What is the ph of a mol/l HCl solution? Solution. Select the expression that allows you to solve for the unknown quantity. ph = -log [H + ] Substitute the given information, and solve for the unknown quantity. ph = -log = -log [1.33 X 10-1 ] = -( ) ph = -(-0.876) ph = b. Example 2. What is the ph of a mol/l acid solution that is ionized 1.8%? Solution. From previous discussion, hydrogen or hydroxide does not contribute to the acidity or alkalinity of a solution unless ionized. So in this problem consider only that hydrogen ion that is ionized. ph = -log [H + ] ph = -log [(0.020 mol/l) (0.018)] = -log [3.6 x 10-4 ] = -( ) ph = 3.4 MD

10 c. Example 3. Determine the ph of a mol/l HC 2 H 3 O 2 solution. The K a of the acid is 1.75 X Solution. In determining the ph of a solution of weak electrolyte, you must first calculate the hydrogen ion concentration. Acetic acid ionizes as follows: HC 2 H 3 O 2 <====> H + + C 2 H 3 O 2 Write the equilibrium expression: [H + ][C 2 H 3 O 2 ] K a = [HC 2 H 3 O 2 ] Substitute the given information, and solve for the hydrogen ion concentration. [H + ] [C 2 H 3 O 2 - ] 1.75 X 10 5 mol/l = mol/l Substitute the variable x for H + and C 2 H 3 O 2, since one hydrogen ion and one acetate ion are produced for every dissociated molecule of HC 2 H 3 O 2. [H + ] [C 2 H 3 O 2 - ] = (1.75 X 10-5 ) ( mol/l) x 2 = (1.75 X 10-5 mol/l) ( mol/l) x 2 = 1.75 X 10-7 mol 2 /L 2 x = [H + ] = 4.18 X 10-4 mol/l Using the calculated value for the hydrogen ion concentration, determine the ph of the solution. ph = -log [H + ] ph = -log [4.18 X 10-4 mol/l] = ( ) ph = -(-3.38) ph = 3.38 MD

11 9-12. poh poh is mathematically defined as: -log [OH - ] or log 1/[OH - ] NOTE: ph and poh have no unit of report ph SCALE a. ph range: 0 to 14 (see figure 9-1). b. Neutral: ph = 7 c. Acidic: less than ph 7 d Basic: greater than ph 7 ph below 7 ph = 7 ph above More Neutral More Acidic Basic Figure 9-1. ph scale. e. In examining the definition of ph, we find that there is an inverse relationship between hydrogen ion concentration and ph. As [H + ] increases, ph decreases and vice versa. Also, notice that each increase of one unit on the ph scale corresponds to a tenfold decrease in [H + ], and each decrease of one unit on the ph scale corresponds to a tenfold increase in [H + ]. If this is true, then as the [H + ] increases, [HO - ] decreases, and as [H + ] decreases, [OH - ] increases poh SCALE a. poh range: 0-14 (see figure 9-2). b. Neutral: poh = 7 c. Acidic: greater than poh 7 d. Basic: less than poh 7 MD

12 poh below 7 poh = 7 poh above More Neutral More Basic Acidic Figure 9-2. poh scale RELATIONSHIP BETWEEN ph AND poh K w = [H + ] [OH - ] = 1.0 X pk w = ph + poh 14 = ph + poh a. Example 1. What is the poh of a H 2 SO 4 solution that has a ph of 4.3? Solution. Select the expression that allows you to solve for the unknown quantity. 14 = ph + poh Substitute the given information, and solve for the unknown quantity. 14 = poh poh = poh = 9.7 MD

13 b. Example 2. What is the ph of a mol/l NaOH solution? Solution. In solving this problem, it is necessary to first determine the poh of the solution before solving for the ph. 1 poh = log = Now, utilize the expression that relates ph to poh by substituting the given information and solving for the unknown quantity. 14 = ph + poh 14 = ph ph = ph = DISCUSSION Section V. HYDROLYSIS OF SALTS If you were to place a salt in water and then perform a ph determination, you would be surprised to find that some salts would have an acidic ph, some would be basic, and others would be neutral. Most salts are formed by the reaction of acids with bases. The anion (-) of the acid and the cation (+) of the base are the component parts of a salt molecule. The term hydrolysis refers to a reaction with water. A salt when placed in water will ionize and depending on the type of salt, will undergo hydrolysis (remember water itself ionizes to a small degree). There are three types of salts we will consider: salts that are composed of the ions of a weak acid and a strong base, salts of a strong acid and a weak base, and salts of a weak acid and a weak base. Anions that form a strong acid (NO 3 -, Cl -, C10 4 -, Br - and I - ) and cations that form strong bases (Group IA and IIA) do not undergo hydrolysis but simply dissociate into ions: (i.e., NaCl does not hydrolyze in water). This information will help in understanding the action of buffers HYDROLYSIS OF THE SALT OF A WEAK ACID AND A STRONG BASE a. This salt will hydrolyze to form a basic solution. The salt sodium acetate will ionize into sodium ions and acetate ions. The sodium ion does not undergo hydrolysis but the acetate ion will react with free hydrogen ions forming acetic acid. Na + + C 2 H 3 O HOH <====> HC 2 H 3 O 2 + Na + +OH - MD

14 b. This reaction causes a shift in the [H + ]/[OH - ] by removing [H + ]. This salt is classified as a basic salt because the acetate ion, by definition, is a weak Bronsted- Lowry base (proton acceptor) HYDROLYSIS OF THE SALT OF A STRONG ACID AND A WEAK BASE a, The ions of this type of salt will hydrolyze to form an acidic solution. The salt ammonium chloride reacts as follows: NH Cl - + HOH <====> NH 3 + H 3 O + + Cl - b. In this case, the ammonium cation is a Bronsted-Lowry acid (proton donor). This salt is classified as an acidic salt HYDROLYSIS OF THE SALT OF A WEAK ACID AND A WEAK BASE The ions of this type of salt will hydrolyze to form a solution that may be acidic, basic, or neutral, depending on the strength (ionization constant) of the weak acid and weak base that formed the salt. If the ionization constant of the weak acid is greater than the ionization constant of the weak base, the solution will be acidic. If the constant is greater for the weak base, the solution will be basic. If the constants are equal, the resulting solution will be neutral DISCUSSION Section VI. BUFFERS Buffer systems are commonly used in the laboratory to help maintain a constant ph in a reaction mixture. A buffer solution acts to resist a change in ph. A buffer is composed of either a weak acid and its salt or a weak base and its salt. Buffers made up of a weak acid and it s salt are called acidic buffers and function from ph 0 to 7. Basic buffers consist of a weak base and its salt and function from ph 7 to 14. MD

15 9-21. MECHANISM OF ACTION a. Addition of a Strong Acid. A common buffer used in the laboratory is the acetic acid/acetate buffer. As acid is added [H + ] into the solution, it will react with the acetate anion from the salt (proton acceptor) forming acetic acid. Since acid is added, a shift in the equilibrium of the solution will occur, but the amount of free hydrogen ions in solution will be controlled by the ionization constant of the acetic acid formed and only a slight change in [H + ] takes place. Buffer system: HC 2 H 3 O 2 /NaC 2 H 3 O 2 (Acetic acid/sodium acetate) Buffer system with HCl added: H + + Cl - + Na + + C 2 H 3 O 2 - <====> HC 2 H 3 O 2 + Cl - + Na + b. Addition of a Strong Base. As base is added to this buffer, acetic acid reacts with the base to form salt (acetate ions) and water. Once again a shift in the equilibrium of the solution occurs but with a minimal change in ph. NaOH added: Na + + OH - + HC 2 H 3 O 2 <====> Na + + C 2 H 3 O H 2 O c. Notes. (1) A buffer's ability to resist changes in ph is limited to the concentration of either the weak acid of base and its salt. The addition of an excessive amount of either acid or base will "exhaust" the buffering capacity of the buffer. (2) The closer the ph of the buffer to the pk a or pk b of the weak acid or base respectively the greater the buffering capacity. MD

16 9-22. THE HENDERSON-HASSELBALCH EQUATION The preparation of laboratory buffers can be accomplished by using the Henderson-Hasselbalch equation. The equation is derived from the ionization constant of weak acids and bases. [H + ] [A - ] K = [HA] The hydrogen ion concentration can be calculated by rearranging the equation. K a X [HA] [H + ] = [A - ] Because [H + ] is usually expressed as ph, it is usually more convenient to express all concentration in this equation in logarithmic form. [HA] log [H + ] = log K a + log [A - ] Since ph = -log [H + ] multiply both sides of the equation by -1. [HA] -log [H + ] = -log K a - log [A - ] Restated: [A - ] -log [H + ] = -log K a + log [HA] ph = pk a + log [acid] The expression relating poh to the components of a buffer may be developed similarly. poh = pk b + log [base] MD

17 9-23 SOLVING BUFFER PROBLEMS The most important consideration when preparing a buffer is determining whether an acidic or basic buffer is being prepared. Examine the components of the buffer. If a weak acid and its salt are the components, use the expression for acidic buffers. If a weak base and its salt are used, select the expression for basic buffers. a. Example 1. Calculate the ph of a buffer solution that contains mol/l acetic acid and mol/l sodium acetate. The K a for acetic acid is 1.75 X Solution. Read the problem carefully, and select the expression that allows you to solve for the unknown quantity. ph = pk a + log [acid] Make any necessary conversions. pk a = -log K a pk a = -log (1.75 X 10-5 ) = -( ) pk a = 4.76 Substitute the given information, and solve for the unknown quantity mol/l ph = log mol/l ph = ph = 5.06 MD

18 b. Example 2. What is the ph of a buffer solution that contains 1.50 X 10-3 mol/l NH 4 Cl and 2.00 X 10-4 mol/l NH 4 OH? The pk b for ammonium hydroxide is Solution. Read the problem carefully, and select the expression that allows you to solve for the unknown quantity. Note that you are dealing with a basic buffer from which you must determine ph. poh = pk b + log [base] Substitute the given information, and solve for the unknown quantity X 10-3 mol/l poh = log 2.00 X 10-4 mol/l poh = poh = 5.63 Now that you have determined the poh, using the appropriate expression, determine the ph of the buffer. 14 = ph + poh ph = 14 - poh ph = ph = 8.37 MD

19 c. Example 3. What amount of salt/acid is required to prepare a mol/l acetate buffer at a ph of 5.50? The pk a of acetic acid is Solution. At times, the pk of the acid/base of a buffer and the total concentration of the buffer is known, and the amount of salt and acid/base required to prepare a buffer must be calculated. After reading the problem carefully, select the expression that allows you to solve for the unknown quantity. ph = pk a + log [acid] Substitute the given information, and solve for the unknown quantity = log [acid] = log [acid] 0.74 = log acid] antilog 0.74 = [acid] 5.5 mol/l 5.5 = = [acid] 1 mol/l You have now established the proper ratio of salt and acid that will yield the desired ph. However, the problem states that a molar concentration of mol/l for the buffer is desired. This mol/l concentration is the sum of the mol/l concentrations of the salt and the acid. The mol/l concentration of the buffer, based on your calculations so far, is 6.5 mol/l. The following method is one of several that you may employ to determine the concentrations necessary to yield the proper mol/l concentration of the buffer while maintaining the proper ratio. MD

20 Express the desired mol/l concentration of the buffer as an equality. + [acid] = mol/l Solve the equality for either or [acid]. = mol/l - [acid] Now based on the substitution property, you are able to express the in terms of [acid], and in effect, derive an equation in one variable instead of the two, in the original expression. 5.5 = [acid] mol/l - [acid] 5.5 = [acid] Simplify the expression by clearing the fraction. 5.5 [acid] = mol/l - [acid] Solve the expression for [acid]. 5.5 [acid] + [acid] = mol/l 6.5 [acid] = mol/l mol/l [acid] = 6.5 [acid] = mol/l or equivalently, 1.54 X 10-2 mol/l MD

21 To determine the amount of salt required, substitute the calculated value of the acid concentration in the expression relating the salt and acid concentration to the desired mol/l concentration of the buffer. = mol/l - [acid] = mol/l mol/l = mol/l or equivalently, 8.46 x 10-2 mol/l. d. Example 4. What amount of salt/base is required to prepare a mol/l ammonia buffer at a ph of 9.8? The pk b for ammonium hydroxide is Solution. After reading the problem carefully, note that you are to prepare a basic buffer of a certain ph. Select an expression that will allow you to solve for the unknown quantity. poh = pk b + log [base] Convert ph to poh. 14 = ph + poh poh = 14 - ph poh = poh = 4.2 Substitute the given values, and solve for the unknown quantity. 4.2 = log [base] = log [base] -0.6 = log [base] MD

22 antilog (-0.6) = [base] 0.3 = [base] Express the desired mol/l concentration of the buffer as an equality. + [base] = mol/l Solve the equality for either or [base]. = mol/l - [base] Now, based on the substitution property, you are able to express the in terms of [base], and in effect derive an equation in one variable instead of the two in the original expression. 0.3 = [base] mol/l - [base] 0.3 = [base] Simplify the expression by clearing the fraction. 0.3 [base] = mol/l - [base] Solve the expression for [base]. 0.3 [base] + [base] = mol/l 1.3 [base] = mol/l mol/l [base] = 1.3 [base] = mol/l or equivalently, 7.7 X 10-2 mol/l MD

23 To determine the amount of salt required, substitute the calculated value of the base concentration in the expression relating the salt and base concentration to the desired mol/l concentration of the buffer. = mol/l - [base] = mol/l mol/l = mol/l or equivalently, 2.3 X 10-2 mol/l Continue with Exercises MD

24 EXERCISES, LESSON 9 INSTRUCTIONS: Answer the following exercises by writing the answer in the space provided at the end of the question. After you have completed all the exercises, turn to "Solutions to Exercises" at the end of the lesson and check your answers. For each exercise answered incorrectly, reread the material referenced with the solution. 1. What is the ph of a 4.00 X 10-4 mol/l HCl solution? 2. What is the ph of a mol/l HC 2 H 3 O 2 that ionizes 1.3% 3. What is the poh of a mol/l H 2 SO 4 solution? (NOTE: Use the given concentration for ph and poh calculations that involve polyprotic acids, that is, acids with more than one hydrogen.) 4. What is the ph of a 1.40 X 10-2 mol/l Ca(OH) 2 solution? (NOTE: To determine the actual hydroxide concentration of this and like compounds, multiply the given concentration by the number of hydroxide ions per molecule.) MD

25 5. What is the ph of a buffer prepared by adding 1.20 X 10-3 mol/l NaC 2 H 3 O 2 and 1.20 X 10-2 mol/l HC 2 H 3 O 2? The K a for acetic acid is 1.75 X What is the poh of a buffer prepared by adding 3.50 X 10-5 mol/l NH 4 OH and 2.50 X 10-4 mol/l NH 4 Cl? The pk b for NH 4 OH is What is the ph of the buffer in exercise 6? 8. An acetate buffer, ph 5.20, was prepared using mol/l acetic acid. The pk a for acetic acid is What concentration of salt is needed? 9. A mol/l bicarbonate buffer with a ph of 5.60 is to be prepared. The pk a of carbonic acid is What concentration of sodium bicarbonate and carbonic acid are needed to prepare the buffer? Check Your Answers on Next Page MD

26 SOLUTIONS TO EXERCISES, LESSON 9 1. ph = 3.40 (para 9-11) 2. ph = 2.9 (para 9-11) 3. poh = 13.7 (para 9-12) 4. ph = 12.4 (para 9-15) 5. ph = 3.76 (para 9-23) 6. poh = 5.60 (para 9-23) 7. ph = 8.40 (para 9-23) 8. = mol/l (para 9-23) 9. = mol/l [acid] = mol/l (para 9-23) End of Lesson 9 MD

### CHEM 101/105 Aqueous Solutions (continued) Lect-07

CHEM 101/105 Aqueous Solutions (continued) Lect-07 aqueous acid/base reactions a. a little bit more about water Water is a polar substance. This means water is able to "solvate" ions rather well. Another

### Chapter 17. How are acids different from bases? Acid Physical properties. Base. Explaining the difference in properties of acids and bases

Chapter 17 Acids and Bases How are acids different from bases? Acid Physical properties Base Physical properties Tastes sour Tastes bitter Feels slippery or slimy Chemical properties Chemical properties

### Acids and Bases: Definitions. Brønsted-Lowry Acids and Bases. Brønsted-Lowry Acids and Bases CHEMISTRY THE CENTRAL SCIENCE

CHEMISTRY THE CENTRAL SCIENCE Professor Angelo R. Rossi Department of Chemistry Spring Semester Acids and Bases: Definitions Arrhenius Definition of Acids and Bases Acids are substances which increase

### Chem101: General Chemistry Lecture 9 Acids and Bases

: General Chemistry Lecture 9 Acids and Bases I. Introduction A. In chemistry, and particularly biochemistry, water is the most common solvent 1. In studying acids and bases we are going to see that water

### UNIT (6) ACIDS AND BASES

UNIT (6) ACIDS AND BASES 6.1 Arrhenius Definition of Acids and Bases Definitions for acids and bases were proposed by the Swedish chemist Savante Arrhenius in 1884. Acids were defined as compounds that

### Talk in. Arrhenius Acid- Base Definition and ph

Talk in. Arrhenius Acid Base Definition and ph When we think of acids, we typically think of the Arrhenius definition. Svante Arrhenius (18591927) Arrhenius Acid = Any compound that increases the hydronium

### Note: (H 3 O + = hydronium ion = H + = proton) Example: HS - + H 2 O H 3 O + + S 2-

AcidBase Chemistry Arrhenius acid: Substance that dissolves in water and provides H + ions Arrhenius base: Substance that dissolves in water and provides OH ions Examples: HCl H + and Cl Acid NaOH Na +

### CHEM 12 Acids and Bases 3/22/2016

Acids and Bases Name: Expected background knowledge from acids and bases introductory reading: Definitions (Arrhenius, BL) of an acid and base Definitions of conjugate acid and base pairs Properties of

### CHM1 Review for Exam 12

Topics Solutions 1. Arrhenius Acids and bases a. An acid increases the H + concentration in b. A base increases the OH - concentration in 2. Strong acids and bases completely dissociate 3. Weak acids and

### Notes: Acids and Bases

Name Chemistry Pre-AP Notes: Acids and Bases Period I. Describing Acids and Bases A. Properties of Acids taste ph 7 Acids change color of an (e.g. blue litmus paper turns in the presence of an acid) React

### AP Chemistry- Acids and Bases General Properties of Acids and Bases. Bases- originally defined as any substance that neutralized an acid

AP Chemistry Acids and Bases General Properties of Acids and Bases Acids Electrolyte Taste Litmus Phenolphthalein React with metals to give off H 2 gas H 2 SO 4 (aq) + Mg (s) MgSO 4 (aq) + H 2 (g) Ionize

### ionic substances (separate) based on! Liquid Mixtures miscible two liquids that and form a immiscible two liquids that form a e.g.

Unit 7 Solutions, Acids & Bases Solution mixture + solvent - substance present in the amount solute - in the solvent solvent molecules solute particles ionic substances (separate) based on! Liquid Mixtures

### BRØNSTED ACIDS & BASES

ACIDS & BASES BRØNSTED ACIDS & BASES BRØNSTED ACIDS & BASES Brønsted acids are proton donors. Brønsted bases are proton acceptors. Amphoteric species can act as either an acid or a base, depending on the

### Acids and Bases: A Brief Review

Acids and : A Brief Review Acids: taste sour and cause dyes to change color. : taste bitter and feel soapy. Arrhenius: acids increase [H ] bases increase [OH ] in solution. Arrhenius: acid base salt water.

### Chapter 19: Acids and Bases Homework Packet (50 pts) Name: Score: / 50

Chapter 19: Acids and Bases Homework Packet (50 pts) Topic pg Section 19.1 1-3 Section 19.2 3-6 Section 19.3 6-7 Section 19.4 8 Naming Acids 9 Properties of Acids/Bases 10-11 Conjugate Acid/Base Pairs

### Since we will be dealing with aqueous acid and base solution, first we must examine the behavior of water.

Acids and Bases Know the definition of Arrhenius, Bronsted-Lowry, and Lewis acid and base. Autoionization of Water Since we will be dealing with aqueous acid and base solution, first we must examine the

### ph of strong acid and base

ph of strong acid and base What does strong mean in terms of acids and bases? Solubility. Basically, if you say an acid or base is strong, then it dissociates 100% in water. These types of situations are

### Auto-ionization of Water

2H 2 O H 3 O + + OH Hydronium ion hydroxide ion Q: But how often does this happen? This is the fundamental concept of all acid-base chemistry In pure water, how much of it is water and how much is ions?

### Chapter 14 - Acids and Bases

Chapter 14 - Acids and Bases 14.1 The Nature of Acids and Bases A. Arrhenius Model 1. Acids produce hydrogen ions in aqueous solutions 2. Bases produce hydroxide ions in aqueous solutions B. Bronsted-Lowry

### Acids and Bases: A Brief Review, see also pp and pp Brønsted-Lowry Acids and Bases 143. The H + Ion in Water

Quiz number 5 will be given in recitation next week, Feb 26Mar 2 on the first part of Chapter 16, to be covered in lectures this week. 16.1 Acids and Bases: A Brief Review 16.2 BronstedLowry Acids and

### Lecture 6. Classes of Chemical Reactions

Lecture 6 Classes of Chemical Reactions Lecture 6 Outline 6.1 The Role of Water as a Solvent 6.2 Precipitation Reactions 6.3 Acid-Base Reactions 1 Electron distribution in molecules of H 2 and H 2 O The

### Chapter 14: Acids and Bases

Ch 14 Page 1 Chapter 14: Acids and Bases Properties of Acids Sour taste React with some metals Turns blue litmus paper red React with bases Some Common Acids HCl, hydrochloric acid H 2 SO 4, sulfuric acid

### WEAK ACIDS AND BASES

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

### Acid Base Concepts. Arrhenius concept. Hydronium Ion. Page 1

Acid Base Concepts Page 1 The Swedish chemist, Svante Arrhenius, framed the first successful concept of acids and bases. He defined acids and bases in terms of their effect on water. According to Arrhenius,

### CHAPTER 16: ACIDS AND BASES

CHAPTER 16: ACIDS AND BASES Active Learning: 4, 6, 14; End-of-Chapter Problems: 2-25, 27-58, 66-68, 70, 75-77, 83, 90-91, 93-104 Chapter 15 End-of-Chapter Problems: 69-74, 125, 129, 133 16.1 ACIDS AND

### Name: Per: Date: Unit 11 - Acids, Bases and Salts Chemistry Accelerated Chemistry I Define each of the following: 1. Acidic hydrogens.

Name: Per: Date: Unit 11 - Acids, Bases and Salts Chemistry Accelerated Chemistry I Define each of the following: 1. Acidic hydrogens 2. Binary acids 3. Oxyacids 4. Carboxylic acid 5. Amines Name the following

### Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory.

Acid-base A4 1 Acid-base theories ACIDS & BASES - IONIC EQUILIBRIA 1. LEWIS acid electron pair acceptor H, AlCl 3 base electron pair donor NH 3, H 2 O, C 2 H 5 OH, OH e.g. H 3 N: -> BF 3 > H 3 N BF 3 see

### CHAPTER 9. ANS: a. ANS: d. ANS: c. ANS: a. ANS: c

CHAPTER 9 1. Which one of the following is the acid in vinegar? a. acetic acid b. citric acid c. muriatic acid d. ascorbic acid 2. Which is a basic or alkaline substance? a. gastric fluid b. black coffee

### Name period Unit 9: acid/base equilibrium

Name period Unit 9: acid/base equilibrium 1. What is the difference between the Arrhenius and the BronstedLowry definition of an acid? Arrhenious acids give H + in water BronstedLowry acids are proton

### UNIT 14 - Acids & Bases

COMMON ACIDS NOTES lactic acetic phosphoric citric malic PROPERTIES OF ACIDS 1. 1. PROPERTIES OF BASES 2. 2. 3. 3. 4. 4. 5. 5. NAMING ACIDS NOTES Binary acids (H + one element) Practice: 1. hydro- - HF

### H 2 O + HNO 3 H 3 O + + NO 3

Properties Unit 12 Acids & Bases electrolytes sour taste turn litmus red react with metals to form 2 gas vinegar, soda, citrus fruits electrolytes bitter taste turn litmus blue slippery feel ammonia, lye,

### ph: Measurement and Uses

ph: Measurement and Uses One of the most important properties of aqueous solutions is the concentration of hydrogen ion. The concentration of H + (or H 3 O + ) affects the solubility of inorganic and organic

### Types of Reactions. What are Acids &Bases? Chapter 15. Acids & Bases. Definition? a) Arrhenius. b) Bronsted-Lowry. c) Lewis

Chapter 15. Acids & Bases Acid/Base Definitions Types of Acids/bases Polyprotic Acids The Ion Product for Water The ph and Other p Scales Aqueous Solutions of Acids and Bases Hydrolysis The Common Ion

### 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.

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.

### Chapter 9 Acids, Bases and Buffers in the Body Outline 9.1 Acids and Bases Definitions Acids

Lecture Presentation Chapter 9 Acids, Bases and Buffers in the Body Julie Klare Fortis College Smyrna, GA Outline 9.1 Acids and Bases Definitions 9.2 Strong Acids and Bases 9.3 Chemical Equilibrium 9.4

### 9.5 ph and the ph Scale

9.5 ph and the ph Scale Living things prefer a constant ph. Normal blood ph is strictly regulated between 7.35 and 7.45. The ph of a solution is commonly measured either electronically by using an instrument

### All Solutions: the ph will lie between 0 and 14

1 Do p in Your ead Every aqueous solution has a degree of acidity or of basicity; that is, every aqueous solution has a p. There are two factors that will determine the p of a solution. These are the acidic

### Chapter 16 Acid-Base Equilibria

Chapter 16 Acid-Base Equilibria Learning goals and key skills: Understand the nature of the hydrated proton, represented as either H + (aq) or H 3 O + (aq) Define and identify Arrhenuis acids and bases.

### Q.1 Classify the following according to Lewis theory and Brønsted-Lowry theory.

Acid-base 2816 1 Acid-base theories ACIDS & BASES - IONIC EQUILIBRIA LEWIS acid electron pair acceptor H +, AlCl 3 base electron pair donor NH 3, H 2 O, C 2 H 5 OH, OH e.g. H 3 N: -> BF 3 > H 3 N + BF

### Stoichiometry and Aqueous Reactions (Chapter 4)

Stoichiometry and Aqueous Reactions (Chapter 4) Chemical Equations 1. Balancing Chemical Equations (from Chapter 3) Adjust coefficients to get equal numbers of each kind of element on both sides of arrow.

### Chemistry 52. Reacts with active metals to produce hydrogen gas. Have a slippery, soapy feeling. React with carbonates to produce CO 2

ACID AND BASE STRENGTH Experiment #2 PURPOSE: 1. To distinguish between acids, bases and neutral substances, by observing their effect on some common indicators. 2. To distinguish between strong and weak

### 1. Read P. 368-375, P. 382-387 & P. 429-436; P. 375 # 1-11 & P. 389 # 1,7,9,12,15; P. 436 #1, 7, 8, 11

SCH3U- R.H.KING ACADEMY SOLUTION & ACID/BASE WORKSHEET Name: The importance of water - MAKING CONNECTION READING 1. Read P. 368-375, P. 382-387 & P. 429-436; P. 375 # 1-11 & P. 389 # 1,7,9,12,15; P. 436

### SECTION 14 CHEMICAL EQUILIBRIUM

1-1 SECTION 1 CHEMICAL EQUILIBRIUM Many chemical reactions do not go to completion. That is to say when the reactants are mixed and the chemical reaction proceeds it only goes to a certain extent, and

### Acid-Base Equilibrium

AcidBaseEquil 1 Acid-Base Equilibrium See AqueousIons in Chemistry 1110 online notes for review of acid-base fundamentals! Acid- Base Reaction in Aqueous Salt Solutions Recall that use [ ] to mean concentration

### Properties of Aqueous Solutions of Acids and Bases. CHAPTER 10 Acids, Bases and Salts. Properties of Aqueous Solutions of Acids and Bases

CAPTER Acids, Bases and Salts Properties of Aqueous Solutions of Acids and Bases Strong and Weak Acids Acids are substances that generate in aqueous solutions. Strong acids ionize 0% in water. That is,

### 6 Reactions in Aqueous Solutions

6 Reactions in Aqueous Solutions Water is by far the most common medium in which chemical reactions occur naturally. It is not hard to see this: 70% of our body mass is water and about 70% of the surface

### Chemical Reactions in Water Ron Robertson

Chemical Reactions in Water Ron Robertson r2 f:\files\courses\1110-20\2010 possible slides for web\waterchemtrans.doc Properties of Compounds in Water Electrolytes and nonelectrolytes Water soluble compounds

### Chemical Reactions in Water

Chemical Reactions in Water Ron Robertson r2 f:\files\courses\1110-20\2010 possible slides for web\waterchemtrans.doc Acids, Bases and Salts Acids dissolve in water to give H + ions. These ions attach

### We were able to use the RICE expression to determine the ph for the autodissociation of water H 2 O H + + OH - with [H + ] = K w 0.

1 Lecture 10: The Strong Acid/Strong Base Equilibrium Calculation After an entire lecture on water with nothing added, you must be pumped to know that in this lecture something will actually be added to

### Acid/base Definitions. Acid/Base Definitions. Acid / Base Chemistry. Acid/Base Definitions. Identifying Acids and Bases

Acids Identifying Acids and Bases Acid (anhydrides) contains H+ ions as the cation, with and other element as the anion Non-metal oxide H2SO4 HI P2O5 Bases Base (anhydrides) Contains OH- as the anion Combined

### Strong Acids (Know These) Announcements & Agenda (02/23/07) Strengths of Acids/Bases - Ionization. Last Time: Last Time: nsted-lowry Acids & Bases

Announcements & Agenda (0//07) You should be reading Ch 0 this weekend! Quiz Today! Open Review Sessions @ pm on Wed. Low attendance this week Last Time: Bronsted nsted-lowry Acids & Bases acids donate

### Chapter 15 Acids and Bases reading guide.

Chapter 15 Acids and Bases reading guide. Be active while reading the text. Take notes, think about what you ve read, and ask yourself questions while reading. Use this document as a guide for making your

### CHAPTERS 15 FAKE TEST QUESTIONS. 1. According to the Brønsted Lowry definition, which species can function both as an acid and as a base?

You might need to know the following K values: CHAPTERS 15 FAKE TEST QUESTIONS CH 3 COOH K a = 1.8 x 10 5 Benzoic Acid K a = 6.5 x 10 5 HNO 2 K a = 4.5 x 10 4 NH 3 K b = 1.8 x 10 5 HF K a = 7.2 x 10 4

### EOC Review Acids Bases and Salts

EOC Review Acids Bases and Salts 1.Identify the Bronsted-Lowry acid and base in each of the following reactions. 2.The hydroxide ion is 3. The hydronium ion is 4.HCl is a strong/weak acid? 5.CH 3 COOH

### Chapter 17. The best buffer choice for ph 7 is NaH 2 PO 4 /Na 2 HPO 4. 19)

Chapter 17 2) a) HCl and CH 3 COOH are both acids. A buffer must have an acid/base conjugate pair. b) NaH 2 PO 4 and Na 2 HPO 4 are an acid/base conjugate pair. They will make an excellent buffer. c) H

### If we write these equations in ionic form, in each case the net ionic equation is the same; H 3 O + (aq) + OH - (aq) H 2H 2 O(l)

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

### Experiment 9 - Double Displacement Reactions

Experiment 9 - Double Displacement Reactions A double displacement reaction involves two ionic compounds that are dissolved in water. In a double displacement reaction, it appears as though the ions are

### Chapter 15: Acids, Bases, and Salts. 15.1: Acids and Bases

Chapter 15: Acids, Bases, and Salts Name: 15.1: Acids and Bases Define an Acid: Define a Base: Ex of an acid in aqueous solution: Ex of a base in aqueous solution: List some of the properties of acids

### p3 Recognizing Acid/Base Properties when p11 Recognizing Basic versus Nonbasic

General Chemistry II Jasperse Acid-Base Chemistry. Extra Practice Problems 1 General Types/Groups of problems: Conceptual Questions. Acids, Bases, and p1 K b and pk b, Base Strength, and using K b or p7-10

### Factors that Affect the Rate of Dissolving and Solubility

Dissolving Factors that Affect the Rate of Dissolving and Solubility One very important property of a solution is the rate of, or how quickly a solute dissolves in a solvent. When dissolving occurs, there

### Chapter 4 Notes - Types of Chemical Reactions and Solution Chemistry

AP Chemistry A. Allan Chapter 4 Notes - Types of Chemical Reactions and Solution Chemistry 4.1 Water, the Common Solvent A. Structure of water 1. Oxygen's electronegativity is high (3.5) and hydrogen's

### Q1: What is the ph Scale? Q6: As acids become more acidic, their ph values

Q1: What is the ph Scale? Q6: As acids become more acidic, their ph values increase or decrease? Q2: The range of values of the ph scale is: Q7: As bases become more alkaline, their ph values increase

### Bronsted- Lowry Acid Base Chemistry

Bronsted Lowry Acid Base Chemistry Just a few reminders What makes an acid an acid? A BronstedLowry Acid is a compound that donates a proton (a hydrogen ion with a positive charge, H + ) o Think of the

### Suggested Problems: p. 625-627 #58, 59, 65, 69, 74, 80, 85, 86, 90, 92, 93, 98, 99

Chemistry I Accelerated Study Guideline - Chapter 19 Acids, Bases and Salts ------------------------------------------------------------------------------ By the end of this unit, the skills you should

### EXPERIMENT 10: Electrical Conductivity Chem 111

EXPERIMENT 10: Electrical Conductivity Chem 111 INTRODUCTION A. Electrical Conductivity A substance can conduct an electrical current if it is made of positively and negatively charged particles that are

### Aqueous Solutions. Water is the dissolving medium, or solvent. Some Properties of Water. A Solute. Types of Chemical Reactions.

Aqueous Solutions and Solution Stoichiometry Water is the dissolving medium, or solvent. Some Properties of Water Water is bent or V-shaped. The O-H bonds are covalent. Water is a polar molecule. Hydration

### I. Definitions: Name: Period: Date: 1. Arrhenius (1887)- produce in aqueous solutions produce in aqueous solutions

Name: Period: Date: I. Definitions: 1. Arrhenius (1887)- produce in aqueous solutions produce in aqueous solutions 2. Bronsted-Lowry (1923) 3. Lewis (1923), so only allows for aqueous solutions only protic

### Chapter 13 & 14 Practice Exam

Name: Class: Date: Chapter 13 & 14 Practice Exam Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Acids generally release H 2 gas when they react with a.

### IB Chemistry 1 Mole. One atom of C-12 has a mass of 12 amu. One mole of C-12 has a mass of 12 g. Grams we can use more easily.

The Mole Atomic mass units and atoms are not convenient units to work with. The concept of the mole was invented. This was the number of atoms of carbon-12 that were needed to make 12 g of carbon. 1 mole

### 4. Acid Base Chemistry

4. Acid Base Chemistry 4.1. Terminology: 4.1.1. Bronsted / Lowry Acid: "An acid is a substance which can donate a hydrogen ion (H+) or a proton, while a base is a substance that accepts a proton. B + HA

### Acids and Bases. Chapter 16

Acids and Bases Chapter 16 The Arrhenius Model An acid is any substance that produces hydrogen ions, H +, in an aqueous solution. Example: when hydrogen chloride gas is dissolved in water, the following

### The component present in larger proportion is known as solvent.

40 Engineering Chemistry and Environmental Studies 2 SOLUTIONS 2. DEFINITION OF SOLUTION, SOLVENT AND SOLUTE When a small amount of sugar (solute) is mixed with water, sugar uniformally dissolves in water

### Chapter 16: Acid-Base and Solubility Equilibria: Reactions in Soil and Water

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,

### Acids and Bases. An Introduction. David A Katz Department of Chemistry Pima Community College, Tucson, AZ, USA

Acids and Bases An Introduction David A Katz Department of Chemistry Pima Community College, Tucson, AZ, USA Properties of Acids 1. Sour taste (examples: vinegar, citric acid, lemon juice) 2. Turns litmus

### Molarity of Ions in Solution

APPENDIX A Molarity of Ions in Solution ften it is necessary to calculate not only the concentration (in molarity) of a compound in aqueous solution but also the concentration of each ion in aqueous solution.

### 6) Which compound is manufactured in larger quantities in the U.S. than any other industrial chemical?

MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Which statement concerning Arrhenius acid-base theory is not correct? A) Acid-base reactions must

### 1. For the equilibrium that exists in an aqueous solution of nitrous acid (HNO 2, a weak acid), the equilibrium constant expression is:

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 =

### Experiment 8 - Double Displacement Reactions

Experiment 8 - Double Displacement Reactions A double displacement reaction involves two ionic compounds that are dissolved in water. In a double displacement reaction, it appears as though the ions are

### Arrhenius Theory of Acids

Acids and Bases Chapter 17: 5, 6, 7, 9, 11, 13, 17, 18, 43, 67a-d, 71 Chapter 18: 5-9, 26, 27a-e, 32 Arrhenius Theory of Acids an acid-base reaction involves the reaction of hydrogen ions and hydroxide

### Acid-Base (Proton-Transfer) Reactions

Acid-Base (Proton-Transfer) Reactions Chapter 17 An example of equilibrium: Acid base chemistry What are acids and bases? Every day descriptions Chemical description of acidic and basic solutions by Arrhenius

### CHEM 102: Sample Test 5

CHEM 102: Sample Test 5 CHAPTER 17 1. When H 2 SO 4 is dissolved in water, which species would be found in the water at equilibrium in measurable amounts? a. H 2 SO 4 b. H 3 SO + 4 c. HSO 4 d. SO 2 4 e.

### Lab Activity: Strong Acids & Strong Bases, Weak Acids & Weak Bases, and the Hydrolysis of Salts

Lab Activity: Strong Acids & Strong Bases, Weak Acids & Weak Bases, and the Hydrolysis of Salts Strong acids and strong bases completely ionize in water to make hydronium or hydroxide ions. Because the

### Acids and Bases. Basic Definitions & Concepts

Acids and Bases CHEM 102! T. Hughbanks! Basic Definitions & Concepts Most basic concepts are given clearly in your text - these notes will only list these as topics discussed, so there will be less detail.!

### 25.1 Acids, Bases, and ph

In the Investigations, you measured several indicators of water quality, including the ph. You may remember that ph values range from 0 to 14. Low values (0 to 6) indicate that a solution is acidic whereas

### Acids and Bases. When an acid loses a proton, the resulting species is its conjugate base. For example, NH 3 + H +

Acids and Bases Definitions An acid is a proton donor, e.g. HCl. For example, consider the reaction between HCl and H 2 O. HCl + H 2 O H 3 O + + Cl - Acid In this reaction, HCl donates a proton to H 2

### 3 The Preparation of Buffers at Desired ph

3 The Preparation of Buffers at Desired ph Objectives: To become familiar with operating a ph meter, and to learn how to use the Henderson-Hasselbalch equation to make buffer solutions at a desired ph

### Topic 5. Acid and Bases

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

### Acids and Bases. Ch a pt e r Aqueous Equilibria: Chemistry 4th Edition McMurry/Fay. MOH(aq) M + (aq) + OH (aq)

15 Ch a pt e r Aqueous Equilibria: Acids and Bases Chemistry th Edition McMurry/Fay Dr. Paul Charlesworth Michigan Technological University AcidBase Concepts 01 Arrhenius Acid: A substance which dissociates

### ph. Weak acids. A. Introduction

ph. Weak acids. A. Introduction... 1 B. Weak acids: overview... 1 C. Weak acids: an example; finding K a... 2 D. Given K a, calculate ph... 3 E. A variety of weak acids... 5 F. So where do strong acids

### 2 Stoichiometry: Chemical Arithmetic Formula Conventions (1 of 24) 2 Stoichiometry: Chemical Arithmetic Stoichiometry Terms (2 of 24)

Formula Conventions (1 of 24) Superscripts used to show the charges on ions Mg 2+ the 2 means a 2+ charge (lost 2 electrons) Subscripts used to show numbers of atoms in a formula unit H 2 SO 4 two H s,

### Chapter 6: Neutralizing the Threat of Acid Rain

Chapter 6: Neutralizing the Threat of Acid Rain Is normal rain acidic? Is acid rain worse in some parts of the country? Is there a way to neutralize acid rain? Acid Rain The problem Regional atmospheric

### Chemistry 3202. Unit 2 Acids and Bases

Chemistry 3202 Unit 2 Acids and Bases Definitions of Acids and Bases An operational definition is one that is based on the observable properties, behaviours or uses of an entity. The earliest definitions

### Chapter 4 Chemical Reactions

Chapter 4 Chemical Reactions I) Ions in Aqueous Solution many reactions take place in water form ions in solution aq solution = solute + solvent solute: substance being dissolved and present in lesser

### Ch Acids and Bases. Arrhenius Definition Acids produce hydrogen ions in aqueous solution. Bases produce hydroxide ions when dissolved in water.

Ch 15-16 Acids and Bases Arrhenius Definition Acids produce hydrogen ions in aqueous solution. Bases produce hydroxide ions when dissolved in water. Limits to aqueous solutions. Only one kind of base.

### Ch 8.5 Solution Concentration Units % (m/m or w/w) = mass of solute x 100 total mass of solution mass of solution = mass solute + mass solvent

1 Ch 8.5 Solution Concentration Units % (m/m or w/w) = mass of solute x 100 total mass of solution mass of solution = mass solute + mass solvent % (v/v) = volume of solute x 100 volume of solution filled

### stoichiometry = the numerical relationships between chemical amounts in a reaction.

1 REACTIONS AND YIELD ANSWERS stoichiometry = the numerical relationships between chemical amounts in a reaction. 2C 8 H 18 (l) + 25O 2 16CO 2 (g) + 18H 2 O(g) From the equation, 16 moles of CO 2 (a greenhouse

### NH 3 + H 2 O + OH - NH 4. Acid-Base Concepts -- Chapter 15 + H + Conjugate Acid-Base Pairs: - H + base. acid

Acid-Base Concepts -- Chapter 15 1. Arrhenius Acid-Base Concept (last semester) Acid: H+ supplier Base: OH- supplier 2. Brønsted-Lowry Acid-Base Concept (more general) (a) Definition (H+ transfer) Acid: