1 188 Chapter 11: Acids and Bases For our purposes, an acid is a substance that produces hydrogen ion (H + ) when dissolved in water. A base is a substance that produces hydroxide ion (OH - ) when dissolved in water. These are the Arrhenius definitions of acids and bases, named for Swedish chemist Svante August Arrhenius ( ), who first defined them. Arrhenius proposed this definition of acids and bases in his 150- page doctoral thesis presented in Among the many ideas he proposed, the most important was that neither salts nor pure water conducted electricity, but that salt solutions did conduct electricity. The explanation was that salt dissociated into anions and cations. While we accept this idea as obvious today, in 1884 it was outrageous, and Arrhenius barely received a passing mark on his work. In 1903, Arrhenius won the Nobel Prize in Chemistry (the third Nobel Prize ever given) for the work reported in his thesis. There is another, complimentary, definition of acids/bases Brønsted- Lowry acids/bases. This definition is named for Danish chemist Johannes Nicholar Brønsted ( ) and English chemist Thomas Martin Lowry ( ). Working independently, these two scientists developed essentially the same definition of acids and bases. A Brønsted- Lowry acid donates hydrogen ion, while a Brønsted- Lowry base accepts hydrogen ion. Brønsted- Lowry acid- base theory is more general than Arrhenius, and all Arrhenius acids and bases are also Brønsted- Lowry bases. However, the reverse is not true. There are several different ways of classifying acids and bases. Two of these classifications are: is the acid (or base) strong or weak, and is the acid (or base) organic or inorganic? An acid (or base) is strong if ~100% of the acid (or base) molecules ionize to form hydrogen ion (or hydroxide ion) in water. If the acid (or base) is weak, then << 100% of the acid (or base) molecules ionize to form hydrogen ion (or hydroxide ion) in water. Normally, the concentration of acid or base is set at 0.10M when this comparison is made. Acids and bases tend to be either strong or very weak. One of the strongest of the weak acids is acetic acid, CH3CO2H. In water (0.10M concentration), it ionizes ~1%. Organic acids are composed of carbon, hydrogen, and oxygen. The acid part of the organic acid molecule is called a carboxylic acid group (CO2H or COOH). When organic acids ionize, they loose hydrogen ion from the carboxylic acid group not from any other location in the molecule! Organic acids are covered in more detail in organic chemistry.
2 189 Inorganic acids are generally composed of nonmetallic elements. The polyatomic ions you memorized (or should have) are portions of the inorganic acids. Adding hydrogen ion to the polyatomic ions produces the inorganic acids. This subject is also covered in Chapter 4. All organic acids, and almost all organic bases are classified as weak. Many inorganic acid and bases are also weak. This reduces the total number of strong acids and bases to a manageable number. MEMORIZE THESE STRONG ACIDS AND BASES (Table 11.1). Any acid (or base) not classified as strong is a weak acid (or base) by default. Strong Acids: Strong Base: Formula Name Formula Name HCl Hydrochloric acid LiOH Lithium hydroxide HBr Hydrobromic acid NaOH Sodium hydroxide HI Hydroiodic acid KOH Potassium hydroxide HNO3 Nitric acid RbOH Rubidium hydroxide HClO4 Perchloric acid CsOH Cesium hydroxide H2SO4 Sulfuric acid Ca(OH)2 Calcium hydroxide Properties of acids and bases. Table Strong acids and strong bases. Acids share a set of common properties. Probably the first of these properties observed was taste acids tend to have a sour taste. This property was likely first observed with acetic acid. When people made wine, over time the wine would sour. The alcohol slowly oxidized to acetic acid causing souring. It was this same slow oxidation of alcohol to acetic acid that was used to make vinegar (which is just a dilute solution of acetic acid in water, with some trace substances). Let me be completely clear about the sour taste of acids property: NEVER TASTE ANYTHING IN THE CHEMISTRY LAB UNLESS YOU WANT TO DIE! The history of chemistry is full of scientists who have died from tasting their experiments. This is not an experiment that needs to be replicated, and you don t need to imitate them.
3 190 Acids tend to change the colors of certain kinds of dyes used as indicators: a substance that changes color with acids or bases. One widely used indicator is litmus. Litmus is blue with bases, and red with acids. Acids react with metals to produce hydrogen gas, and bubbles of this flammable gas can be seen as this reaction proceeds. Bases tend to have a bitter taste and a slippery, soapy feel on the skin. In addition to the warning I gave you about tasting things in the chemistry lab, let me add another warning: NEVER RUB ANYTHING ON YOUR SKIN IN THE CHEMISTRY LAB UNLESS YOU WANT TO BE PERMANENTLY SCARRED AND MAYBE DIE! The slippery, soapy feel of bases was probably the first base property observed, and was noticed when people discovered how to clean wool before dying it different colors. Wool fresh off of the sheep is dirty and oily and has to be cleaned before colored dyes will stick to the wool fibers. Soaking wool in a mixture of wood ashes in water removed the oil, allowing the dyes to stick to the wool. Eventually, people learned to make soap by adding wood ashes (as a source of base) to melted animal fat. It was many years before people routinely used soap and water for personal hygiene, but soap was routinely used for cleaning wool and other fibers before dying. Bases also change indicator colors, and if red litmus is combined with base the litmus become blue. Blue litmus or red litmus is sometimes soaked into strips of paper to make litmus paper, which is more convenient to use than the liquid solutions. Other dyes are sometimes put on paper to make ph paper, allowing us to estimate the actual ph of a solution instead of simply saying, It s acid or It s base. Acids make water acidic by increasing the amount of hydrogen ion present in solution; bases make water basic by increasing the amount of hydroxide ion present in solution: HCl! H 2 O H + + Cl " NaOH! H2 O Na+ + OH " When acids and bases are combined, hydrogen ion reacts with hydroxide ion to form water. Consider the following reactions between various acids and bases:
4 191 HCl + NaOH NaCl + H2O HCl + KOH KCl + H2O HNO3 + NaOH NaNO3 + H2O 2HNO3 + Ca(OH)2 Ca(NO3)2 + 2H2O CH3CO2H + NaOH NaCH3CO2 + H2O In all of these reactions, an acid reacts with a base to produce a salt and water. This is the general pattern of acid base reactions: acids and bases combine to form salts and water. The reaction between acids and bases is called neutralization, represented by the reaction: H + + OH - H2O When acids and bases react, the acids loose their acidic properties and the bases loose their basic properties. Water and ph. Danish chemist Søren Peder Lauritz Sørensen ( ) introduced the concept of ph at Carlsberg Laboratory in According to the Carlsberg Foundation, ph stands for power of hydrogen. By strict definition, ph is related to the activity of hydrogen ion: ph = -log(! H + ) However, it is more common to define ph as the negative log of the molar concentration of hydrogen ion: ph = - log [H + ] We will use this more common definition in this chapter. In water, the concentration of hydrogen ion and hydroxide ion are related by the equation: Kw = 1.00 x = [H + ][OH - ]
5 192 Where the notation [H + ] and [OH - ] indicates the equilibrium molar concentrations (molarity) of hydrogen ion and hydroxide ion. In water, hydrogen ion and hydroxide ion concentrations are inversely related; if one increases the other must decrease. Table 11.2 illustrates this relationship over the ph range of 1 to 13. Look closely at the values given in Table At any ph value, the product of hydrogen ion and hydroxide ion concentration equals 1.00 x For any given ph, we can readily calculate hydrogen ion concentration: [H + ] = 10 - ph In water, the ph defines not only the concentration of hydrogen ion but also the concentration of hydroxide ion. ph [H + ] [OH - ] x x x x x x x x x x x x x x x x x x x x x x x x x x 10-1 Table Molar concentrations of hydrogen ion and hydroxide ion, in water, as a function of ph. We define poh similarly to ph; poh = - log[oh - ]. For water solutions, all we need is one value of ph, or poh, or one concentration for either hydrogen ion or hydroxide ion, to calculate all other values. For example, imagine I have a water solution with ph = 4.5:
6 193!H " + # $ =10%4.5 = = 3.2 &10 %5 M "OH! # $ % = 1.00 &10! &10!5 = 3.1&10!10 M poh = -log# $ 3.1!10 "10 % & = 9.5 We can also use a simpler formula to relate ph and poh: ph + poh = At ph < 7, hydrogen ion concentration is greater than hydroxide ion concentration. Aqueous solutions at ph < 7 are described as acidic. At ph > 7, hydroxide ion concentration is greater than hydrogen ion concentration, and these solutions are described as basic. A ph of 7.00 indicates that hydrogen ion and hydroxide ion concentrations are equal; ph = 7.00 is described as neutral. Be extremely careful in how you use and think about the term neutral. A neutral ph (ph = 7.00) means that the concentrations of hydroxide and hydrogen ion are equal to each other; it absolutely positively does NOT mean that there isn t any hydrogen ion or hydroxide ion! Pure water spontaneously breaks apart into hydrogen ions and hydroxide ions: H2O H + + OH - This is an equilibrium reaction, and the equilibrium constant is 1.00 x This equilibrium is sufficiently important to have it s own distinctive equilibrium constant symbol: Kw. If stoichiometric amounts of strong acids (HCl, HNO3, H2SO4) are combined with strong bases (NaOH, KOH), then the solution ph is very close to 7.0. We make the general statement that Strong acids neutralize strong bases producing a neutral ph (ph ~ 7.00). However, the situation is very different for the reaction of a weak acid with a strong base, or a strong acid with a weak base, or a weak acid with a weak base. When stoichiometric amounts of strong/weak acids and bases are combined, the solution ph is not Conversely, if strong/weak acids and bases are combined until the ph equals 7.00, then stoichiometry hasn t been achieved. The type of acid and base combined tells us the resulting ph of the solution, and the type of salt produced (Table 11.3).
7 194 Acid type Base type Salt type Solution ph (stoichiometric) Strong Strong Neutral ~ 7.0 Strong Weak Acid salt < 7.0 Weak Strong Base salt >7.0 Weak Weak????????????????? Table Salt types and solution ph for stoichiometric combinations of various acid- base types. The salts produced from combining strong acids and bases (NaCl, NaNO3, Na2SO4, KCl, KNO3, K2SO4) are neutral salts. If these neutral salts are dissolved in water, the solution ph is close to 7.0. Strong acids react with weak bases, such as ammonia (ammonium hydroxide). When stoichiometric amounts of strong acids and weak bases are combined, the solution ph is less than 7.0! Salts such as NH4Cl, NH4NO3, (NH4)2SO4 are acid(ic) salts, and the solution ph of these salts is less than 7.0. Weak acids react with strong bases, and when stoichiometric amounts are combined the resulting solution ph is greater than 7.0. The salts produced, such as CH3CO2Na, are base (basic) salts, and the solution ph of these salts is greater than 7.0. For combinations of weak acids with weak bases, no general result can be predicted. Acid- Base Titrations. An acid- base titration is a laboratory procedure involving the addition of measured volumes of an acid (or base) of known concentration to a known volume of base (or acid) for the purpose of determining the concentration of the base (or acid). The most useful equation for acid- base calculations is a version of the dilution equation: namava = nbmbvb Where Ma and Mb are the concentrations of the acid and base respectively, Va and Vb are the volumes of the acid and base, and na and nb are the number of hydrogen ions per molecule of acid, and the number of hydroxide ions per molecule of base.
8 195 Consider a titration of sulfuric acid (H2SO4) with sodium hydroxide. If ml of sodium hydroxide requires ml of M sulfuric acid for neutralization, what is the concentration of sodium hydroxide? The chemical reaction is: H2SO4 + 2NaOH Na2SO4 + 2H2O Notice that sulfuric acid provides 2 hydrogen ions for every molecule of sulfuric acid, while sodium hydroxide provides one hydroxide per molecule of sodium hydroxide. Substituting the known values into our equation gives us: 2 x M x ml = 1 x Mb x ml Mb = M. When stoichiometry is achieved between the acid and the base, then the moles of acid must equal the moles of base (moles of H + = moles OH - ). If we chose to do so, we could solve acid- base calculations using the same techniques used for any other stoichiometry calculation. For this reaction, we can readily calculate that we have moles of sulfuric acid ( moles/liter x L). From the reaction stoichiometry, 2 moles of sodium hydroxide are required for each mole of sulfuric acid. Our moles of sulfuric acid require moles of sodium hydroxide. The concentration of sodium hydroxide is moles of sodium hydroxide/ L = M. One common titration procedure is standardization. This process involves titrating a known amount of a pure, standard material with an acid (or base) for the purpose of determining the concentration of the acid (or base). Once the concentration of the acid (or base) has been determined, it can be used to accurately titrate other substances. Sodium hydroxide solution is typically standardized by titrating a pure form of potassium hydrogen phthalate (abbreviated KHP, Figure 11.1). O O C OH K + O - C Figure Potassium hydrogen phthalate, KHP. The bold- faced hydrogen is the hydrogen ion released by this acid.
9 196 KHP has a formula weight of grams/mole, and there is one hydrogen ion produced (shown in bold) for each molecule of the acid. Imagine we have a sodium hydroxide solution of unknown concentration. We weigh a portion of KHP ( grams), dissolve it in some deionized water, and titrate it with the sodium hydroxide solution until the acid is neutralized, requiring ml of sodium hydroxide. What is the concentration of sodium hydroxide solution? moles KHP = = grams KHP F.W. KHP g g / mole = moles KHP When neutralization is achieved, the moles of sodium hydroxide must equal the moles of KHP. The concentration of sodium hydroxide is: moles NaOH [ NaOH] = = M L There are several methods used to indicate the end of a titration, but one common method involves using an indicator. An indicator is a dye that changes color at specific ph values. Phenolphthalein (Figure 11.2) is a useful indicator for acid- base titrations because of its distinctive color change; in acid solutions, phenolphthalein is colorless while in base solutions it is pink. Generally, 2 or 3 drops of 1% phenolphthalein solution is added to the acid solution. When the solution turns pink, all of the acid has been neutralized and we can stop titrating. HO OH C O C O Figure Phenolphthalein indicator.
10 197 Buffers. A buffer is a solution containing a weak acid and a salt of the same weak acid. An example of a buffer solution is an aqueous mixture of acetic acid and sodium acetate (CH3CO2H and CH3CO2Na). A mixture of acetic acid and sodium chloride is NOT a buffer solution. Buffer solutions have the ability to resist ph changes when small amounts of strong acids or bases are added to the solution. A weak acid does not ionize 100 % as does a strong acid. When a weak acid dissolves in water, equilibrium between the ionized and unionized forms of the acid is rapidly reached, described by the reaction: HA H + + A - Where HA is the unionized acid and A - is the ionized form of the acid. The equilibrium expression for this reaction is:! " K a = H + #! " HA $ A% [ ] # $ Where Ka is the equilibrium constant, and [H + ], [A - ], and [HA] are the equilibrium concentrations of hydrogen ion, ionized acid, and unionized acid respectively. The above expression can be rearranged, producing the Henderson- Hasselbach equation: Where pka = - logka. " # $ ph = pk a + log A! % HA [ ] The equation was first written in 1908 by American physiologist and chemist, Lawrence Joseph Henderson ( ). Henderson is considered by many as one of the leading biochemists of the 20 th century, and he wrote the equation to describe the carbonate buffer system. In 1916, the equation was re- written in its logarithmic form by Danish physician and chemist Karl Albert Hasselbach ( ). Hasselbach was a pioneer in the medical use of ph measurements, and used to equation to study a condition called metabolic acidosis, where the body produces too much acid, reducing the bloods ph. Consider a solution containing M acetic acid and M sodium acetate. The Ka of acetic acid is 1.8 x 10-5 ; therefore the pka is Plugging these values into the Henderson- Hasselbach equation we get:
11 198 [ ] [ ] ph = log M M = (!0.30) = 4.44 What if we added a small amount of strong base (NaOH) to the buffer described above? When sodium hydroxide is added to the buffer, some of the unionized acid will be neutralized and converted to the ionized form. The concentration of HA will decrease, and the concentration of A - will increase. The absolute value of the increase and decrease will be the same as the total moles of sodium hydroxide added. Let s say that we started with ml of the buffer. Before adding any sodium hydroxide we have: M x L = moles A M x L = moles HA Imagine we add 5.00 ml of M sodium hydroxide. This volume of sodium hydroxide solution corresponds to: L x M = moles sodium hydroxide. The A - concentration will increase by moles, and the HA concentration will decrease by the same amount. The total volume of the solution increases by 5.00 ml. The new concentrations of A - and HA are: The resulting ph is: [A - ] = ( )/0.1050L = M [HA] = ( )/0.1050L =0.0429M [ ] [ ] ph = log M M = (!0.18) = 4.56
12 199 The ph has increased by 0.12 ph units. Compare this ph change with a similar situation using plain water instead of buffer solution. Plain water has a ph very close to 7. Adding 5.00 ml of M sodium hydroxide solution results in a final sodium hydroxide concentration of moles/0.1050l = M. The poh is 2.32 so the ph is This is a change of 4.68 units. Clearly, ph changes are smaller in buffer solutions compared to ph changes in ordinary water. A similar calculation shows that addition of small amounts of strong acid changes the buffer ph only slightly. When adding acid, the concentration of unionized weak acid increases, while the concentration of the ionized form decreases; hydrogen ion combines with the ionized acid (A - ) to form more of the unionized acid (HA). Using the same starting buffer information from above: M x L = moles A M x L = moles HA Imagine we add 5.00 ml of M HCl. This volume of HCl corresponds to: L x M = moles hydrochloric acid. The new concentrations of A - and HA will be: The resulting ph is: [A - ] = ( )/0.1050L = M [HA] = ( )/0.1050L =0.0524M ph = log = (!0.44) [ ] M [ ] = 4.30 The ph decreased by 0.14 ph units compared to the starting value of By comparison, adding 5.00 ml of M HCl to ml of plain water produces a hydrogen ion concentration of M. The ph of this solution is 2.32, much lower than the starting ph, 7.0.
13 200 Other general reactions. Acids react with many metals to produce hydrogen gas. The reaction below is representative of these types of reactions. 2HCl + Zn ZnCl2 + H2( ) Acid anhydrides, which are typically non- metal oxides such as CO2, SO2, NO2, etc., react with water to form acids: CO2 + H2O H2CO3 (carbonic acid) SO2 + H2O H2SO3 (sulfurous acid) 2NO2 + H2O HNO3 + HNO2 (nitric and nitrous acid) Metal oxides generally react with water to produce metal hydroxides (bases). For example, sodium oxide or magnesium oxide react with water to produce sodium hydroxide or magnesium hydroxide respectively: Na2O + H2O 2NaOH MgO + H2O Mg(OH)2
14 201 Chapter 11 Homework: Vocabulary. The following terms are defined and explained in the text. Make sure that you are familiar with the meanings of the terms as used in chemistry. Understand that you may have been given incomplete or mistaken meanings for these terms in earlier courses. The meanings given in the text are correct and proper. Acid Base Strong Weak Indicator Litmus paper Buffer ph poh Neutral salts Acid(ic) salts Base(ic) salts Titration Standardization Henderson- Hasselbach equation Neutralization Perform the indicated acid- base calculations. 1. How much phosphoric acid, H3PO4. solution ( M) must be added ml of M calcium hydroxide, Ca(OH)2, to completely neutralize the solution? 2. A sample of benzoic acid, C7H6O2, weighing g and containing one hydrogen ion per molecule of acid, required ml of sodium hydroxide for neutralization. What is the concentration of sodium hydroxide? 3. Which solution requires more M potassium hydroxide, KOH, for neutralization: a) ml of M nitric acid, HNO3 or b) 7.50 ml of M phosphoric acid? 4. Which solution requires more M acetic acid (CH3CO2H, one hydrogen ion per molecule) for neutralization: a) ml of M potassium hydroxide or b) ml of M calcium hydroxide? 5. A ml sample of M sodium hydroxide required ml of hydrochloric acid, HCl, for neutralization. What is the concentration of HCl? Perform the indicated ph calculations. 1. The concentration of hydrogen ion is 3.6 x 10-5 M. Calculate the concentration of hydoxide ion, the ph, and the poh. 2. The ph of a solution is What is [H + ] and [OH - ]?
15 A solution of nitric acid is prepared by diluting ml of M nitric acid to a final volume of ml. What is the expected ph of the diluted solution? ml of M hydrochloric acid is combined with ml of M sodium hydroxide. What is the ph of the final solution? 5. A buffer solution containing acetic acid (CH3CO2H) and sodium acetate (CH3CO2Na) is prepared using grams of acetic acid and grams of sodium acetate dissolved in enough water to produce ml of solution. What is the expected ph of this buffer? The pka for acetic acid is A buffer made from benzoic acid (a monoprotic acid) and sodium benzoate contains M sodium benzoate and M benzoic acid. A 5.00 ml volume of M sodium hydroxide is added to ml of this buffer. By how much will the ph change, i.e. what is the difference between the original ph and the ph after adding the sodium hydroxide? The pka for benzoic acid is How much sodium formate (NaCO2, the salt of formic acid) must be added to grams of formic acid (HCO2H, monoprotic acid), to produce a buffer solution having a ph = 4.00? The pka for formic acid is 3.74.
16 203 Acid- base calculations answers: 1. namava = nbmbvb 3 x M x Va = 2 x M x ml Va = ml 2. Formula weight of benzoic acid is g/mole g / g/mole = moles benzoic acid. At neutralization, moles benzoic acid = moles sodium hydroxide moles sodium hydroxide / L = M 3. namava = nbmbvb2 a) 1 x M x ml = 1 x M x Vb Vb = 39.7 ml b) 3 x M x 7.50 ml = 1 x M x Vb Vb = 10.2 ml 4. namava = nbmbvb a) 1 x M x Va = 1 x M x ml Va = ml b) 1 x M x Va = 2 x M x ml Va = ml 5. namava = nbmbvb 1 x Ma x ml = 1 x M x ml Ma = M
17 204 ph calculation answers: 1. Kw = 1.00 x = [H + ][OH - ] 1.00 x = [3.6 x 10-5 ][OH - ] [OH - ] = 2.8 x ph = - log[h + ] = - log[3.6 x 10-5 ] = = ph + poh = poh = [H + ] = 10 - ph [H + ] = = 3.0 x 10-6 [OH - ] = 1.00 x / 3.0 x 10-6 = 3.3 x MiVi = MfVf M x ml = Mf x ml Mf = M = [H + ] ph = - log[ ] = L x M = moles HCl L x M = moles NaOH NaOH is in excess. Moles of NaOH after reacting with HCl is moles moles = moles NaOH moles / L = M NaOH = [OH - ] poh = - log[ ] = 3.64 ph = = MW CH3CO2H = g/mole FW CH3CO2Na = g/mole
18 205 [CH3CO2H] = (10.69g / g/mole) L = M [CH3CO2Na] = (11.73g / g/mole) L = M ph = pka + log(0.5720m/0.7121m) ph = ( ) = Starting ph of buffer: ph = log(0.0250m/0.0150m) ph = (0.22) = 4.42 Initial moles of salt = L x M = moles Initial moles of acid = L x M = moles Moles NaOH added = L x M = moles Final moles of salt = = moles Final moles of acid = = moles [salt] = moles / L = M [acid] = moles / L = M ph = log(0.0349m/ m) ph = (1.36) = 5.56 change in ph = = 1.14 ph units. 7. F.W. HCO2H = g/mole F.W. NaCO2 = g/mole g HCO2H = moles 4.00 = log ([A - ]/[0.3330]) = [A - ]/[0.3330] = [A - ]/[0.3330]
19 moles = [A- ] = sodium formate moles x g/mole = g sodium formate.
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CHE 1400 - Spring 2015 - Chapter 7 Homework 7 MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1)According to Arrhenius, an acid and a base will react
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
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.
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
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
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.
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
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
Titration 1 Acid-Base Titrations Molarities of acidic and basic solutions can be used to convert back and forth between moles of solutes and volumes of their solutions, but how are the molarities of these
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.!
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 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,
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
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
BASIC CONCEPTS of CHEMISTRY Please revise: names of element, Periodic Table (understanding the notation), acid, base and salt nomenclature 1. Definitions of acid and base There are several methods of defining
CHAPTER 12 Acids and Bases Opening Essay Formerly there were rather campy science-fiction television shows in which the hero was always being threatened with death by being plunged into a vat of boiling
1 Aqueous Equilibria: Buffers & Titrations AMHS AP Chemistry Multiple Choice questions Name Common-Ion Effect 1) The ph of a solution that contains 0.818 M acetic acid (K a = 1.77x10-5 ) and 0.172 M sodium
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
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
Volumetric Analysis Lecture 5 Experiment 9 in Beran page 109 Prelab = Page 115 Experimental Aims To prepare and standardize (determine concentration) a NaOH solution Using your standardized NaOH calculate
Aqueous Ions and Reactions (ions, acids, and bases) Demo NaCl(aq) + AgNO 3 (aq) AgCl (s) Two clear and colorless solutions turn to a cloudy white when mixed Demo Special Light bulb in water can test for
Chemical reactions Classifications Reactions in solution Ionic equations Learning objectives Distinguish between chemical and physical change Write and balance chemical equations Describe concepts of oxidation
Chemistry: Chemical Equations Write a balanced chemical equation for each word equation. Include the phase of each substance in the equation. Classify the reaction as synthesis, decomposition, single replacement,
Chapter 4: Reaction in Aqueous Solution What is a Solution? Solute + substance dissolved typically smaller quantity Solvent! dissolving medium typically larger quantity Solution homogeneous mixture variable
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 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?
The Determination of Acid Content in Vinegar Reading assignment: Chang, Chemistry 10 th edition, pages 153-156. Goals We will use a titration to determine the concentration of acetic acid in a sample of
Materials: ph paper and color chart (ph range 3 to 12) or ph meter distilled water white vinegar household ammonia (or baking soda) spot plate test or 3 small test tubes stirring rod solutions / fruits
Properties of Acids and Bases According to Boyle In 1661 Robert Boyle summarized the properties of acids as follows: 1. Acids have a sour taste. 2. Acids are corrosive. 3. Acids change the color of certain
96 Chapter 7: Calculations with Chemical Formulas and Chemical Reactions Chemical reactions are written showing a few individual atoms or molecules reacting to form a few atoms or molecules of products.
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
Acid and Base Multiple Choice January 1999 21. Consider the following acidbase equilibrium: HCO 3 + H 2 O H 2 CO 3 + OH In the reaction above, the BrönstedLowry acids are A. H 2 O and OH B. HCO 3 and OH
) To make nitric acid (HN 3 ), in industry, the following process is used: NH 3(g) + 2(g) N (g) + H 2 (g) (a) N (g) + 2(g) N 2 (g) ΔH > 0 (b) N 2(g) + H 2 (l) HN 3(aq) + N (g) (c) a) (3 pts) Balance each
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
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
Titrations Titration - a titration is defined as the determination of the amount of an unknown reagent (analyte) through the use of a known amount of another reagent (titrant) in an essentially irreversible
Review of Basic Concepts, Molarity, Solutions, Dilutions and Beer s Law Aqueous Solutions In Chemistry, many reactions take place in water. This is also true for Biological processes. Reactions that take
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 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