6.1 Theories of Acids and Bases A. Naming Acids and Bases Chapter 6: Acids & Bases 6.1 Theories of Acids and Bases A. Naming Acids and Bases acids always have as the state and always have (aq) hydrogen Rules 1. hydrogen becomes acid 2. hydrogen becomes acid 3. hydrogen becomes acid ____ide hydr____ic _____ate _____ic ____ite ____ous

Examples: 1. hydrogen iodide = hydroiodic acid phosphoric acid Change each of the following to the appropriate acid name and give the formula: 1. hydrogen iodide = hydroiodic acid HI(aq) phosphoric acid H3PO4(aq) 2. hydrogen phosphate = 3. hydrogen nitrite = nitrous acid HNO2(aq) 4. hydrogen sulphite = sulphurous acid H2SO3(aq)

sodium hydrogen carbonate most bases are ionic compounds that are named accordingly Examples: Name each of the following bases: 1. NaOH(aq) = sodium hydroxide 2. NaHCO3(aq) = sodium hydrogen carbonate 3. Mg(OH)2(aq) = magnesium hydroxide 4. NH3(aq) = ammonia

aqueous hydrogen iodide IUPAC names for acids and bases are simply the word “aqueous” followed by the ionic name Examples: Write the IUPAC name for each of the following acids and bases: 1. hydroiodic acid = aqueous hydrogen iodide 2. magnesium hydroxide = aqueous magnesium hydroxide 3. sulphurous acid = aqueous hydrogen sulphite 4. sodium hydrogen carbonate = aqueous sodium hydrogen carbonate

B. Properties of Acids and Bases are of a substance empirical properties observable properties acids, bases and neutral substances have some properties that distinguish them and some that are the same

Acids Bases Neutral Substances sour taste bitter taste electrolytes electrolytes, non-electrolytes neutralize bases neutralize acids react with indicators do not react with indicators affect indicators the same way litmus - red litmus - blue bromothymol blue - yellow bromothymol blue - blue phenolphthalein - phenolphthalein - pink colourless react with to produce metals H2(g) pH greater than 7 less than 7 pH pH of 7 eg) HCl(aq), H2SO4(aq) eg) Ba(OH)2(aq) NH3(aq) eg) NaCl(aq), Pb(NO3)2(aq)

C. Arrhenius Definition first proposed theory on acids and bases Svante Arrhenius his theory was that some compounds form electrically charged particles when in solution his explanation of the properties of acids and bases is called the Arrhenius theory of acids and bases

an Arrhenius is a substance that (because it is molecular) to form acid ionizes hydrogen ions, H+(aq), in water an will in an aqueous solution acid increase the [H+(aq)] an Arrhenius is a substance that to form in water base dissociates hydroxide ions, OH(aq), a will in an aqueous solution base increase the [OH-(aq)]

D. Modified Arrhenius Definition the original definition of acids and bases proposed by Arrhenius is good but it has limitations some substances that might be predicted to be are actually neutral basic eg) Na2CO3(aq), NH3(aq) it has been found that not all bases contain the hydroxide ion as part of their chemical formula

an Arrhenius is a substance that in aqueous solution base (modified) reacts with water to produce OH(aq) ions eg)  NH3(aq) + H2O() NH4+(aq) + OH(aq)

when acids ionize, they produce H+(aq) eg) HCl(g)  H+(aq) + Cl(aq) it has been found using analytical technology like X-ray crystallography that in an aqueous solution H+(aq) ions do not exist in isolation the hydrogen ion is extremely positive in charge and water molecules themselves are very polar so… it is that would exist in water without being attracted to the of other highly unlikely hydrogen ions negative poles water molecules

this results in the formation of the hydronium ion + H3O+(aq)

an Arrhenius is a substance that in aqueous solution acid (modified) reacts with water to produce H3O+(aq) ions eg)  HCl(aq) + H2O() Cl(aq) + H3O+(aq)  H2SO3(aq) + H2O() HSO3(aq) + H3O+(aq) SO2 () H2O()

6.2 Strong and Weak Acids and Bases the of a substance depend on two things: acidic and basic properties 1. the of the solution concentration 2. the of the acid or base identity

A. Strong Acids and Weak Acids an acid that ionizes almost in water is called a 100% strong acid eg) HCl(aq) + H2O()  H3O+(aq) + Cl(aq) 100% of the becomes H3O+(aq) and Cl(aq) HCl(aq) the concentration of the is the as the concentration of the it came from H3O+(aq) same acid strong acids are strong electrolytes and react vigorously with metals

there are 6 strong acids: perchloric acid HClO4(aq) hydrobromic acid HBr(aq) hydroiodic acid HI(aq) hydrochloric acid HCl(aq) sulfuric acid H2SO4(aq) nitric acid HNO3(aq) ***on your periodic table

⇌ a and only a small percentage of the acid forms weak acid does not ionize 100% ions in solution eg) CH3COOH(aq) + H2O() ⇌ H3O+(aq) + CH3COO(aq) we use the for weak acids equilibrium arrow weak acids are react much less vigorously with metals weak electrolytes and

B. Strong Bases and Weak Bases a base that dissociates into ions in water is called a 100% strong base are strong bases ionic hydroxides and metallic oxides eg) NaOH(aq)  Na+(aq) + OH(aq) a and only a small percentage of the base forms weak base does not dissociate 100% ions in solution + eg) NH3(aq) + H2O() ⇌ NH4+(aq) OH(aq) we use the for weak bases equilibrium arrow

C. Monoprotic and Polyprotic Acids acids that have only per molecule that can are called one hydrogen atom ionize monoprotic acids eg) HCl(aq), HF(aq), HNO3(aq), CH3COOH(aq) monoprotic acids can be strong or weak

acids that contain that can are called two or more hydrogen atoms ionize polyprotic acids eg) H2SO4(aq), H3PO4(aq) acids with are , with are two hydrogens diprotic three hydrogens triprotic

when polyprotic acids ionize, only hydrogen is removed at a time, with each acid becoming one progressively weaker eg)  H2SO4(aq) + H2O() H3O+(aq) + HSO4(aq) HSO4(aq) + H2O()  H3O+(aq) + SO42(aq)

D. Monoprotic and Polyprotic Bases bases that are called react with water in only one step to form hydroxide ions monoprotic bases eg) NaOH(s) bases that react with water in are called two or more steps polyprotic bases eg) CO32(aq), PO43(aq) ***complex ions with more than 1- charge!!!

as with polyprotic acids, only OH(aq) is formed at a time, and each new base formed is than the last one weaker eg)  CO32(aq) + H2O() OH(aq) + HCO3(aq) HCO3(aq) + H2O()  OH(aq) + H2CO3(aq)

E. Neutralization the reaction between an acid and a base produces an ionic compound and water acid + base a salt + water → eg) HCl(aq) + KOH(aq) → KCl(aq) + HOH() the products of are both neutralization neutral in a neutralization reaction or between a , the product is always acid-base reaction strong acid and a strong base water H3O+(aq) + OH(aq)  2 H2O()

F. Acid and Base Spills there are many uses for both acids and bases in our households and in industry due to their, special care must be used when they are being reactivity and corrosiveness produced and transported

the two ways to deal with acid or base spills are: 1. dilution: reduce the by adding concentration water 2. neutralization: you always use a for the neutralization so you aren’t left with another hazardous situation weak acid or base

A. Ion Concentration in Water 6.3 Acids, Bases and pH A. Ion Concentration in Water the “self-ionization” of water is very small (only 2 in 1 billion) H2O() + H2O()  H3O+(aq) + OH-(aq) the concentration of and are hydronium ions equal and constant in pure water hydroxide ions [H3O+(aq)]= [OH-(aq)] = 1.0 x 10-7 mol/L 1.0 x 10-7 mol/L

B. The pH Scale in 1909, Soren Sorenson devised the pH scale it is used because the [H3O+(aq)] is very small at 25C (standard conditions), most solutions have a pH that falls between 0.0 and 14.0 it is possible to have a pH and a pH negative above 14 it is a based on whole numbers that are powers of 10 logarithmic scale

more acidic more basic neutral there is a for every change in on the pH scale 10-fold change in [H3O+(aq)] 1 eg) a solution with a pH of 11 is times more basic than a solution with a pH of 9 10  10 = 100 pH Scale more acidic more basic 7 14 neutral

C. Calculating pH and pOH pH =  log [H3O+(aq)] ***New sig dig rule: when reporting pH or pOH values, only the numbers to the count as significant right of the decimal place Try These: 1.     [H3O+(aq)] = 1 x 10-10 mol/L pH = 2.     [H3O+(aq)] = 1.0 x 10-2 mol/L pH = 3.     [H3O+(aq)] = 6.88 x 10-3 mol/L pH = 4.     [H3O+(aq)] = 9.6 x 10-6 mol/L pH = 10.0 2.00 2.162 5.02

 H+(aq) + NO3-(aq) HNO3(aq) pH = -log[H+(aq)] = -log[0.133… mol/L] Example 6.30 g of HNO3 is dissolved in 750 mL of water. What is the pH ?  H+(aq) + NO3-(aq) HNO3(aq) m = 6.30 g M = 63.02 g/mol V = 0.750 L c = 0.133…mol/L x 1/1 = 0.133…mol/L n = m M = 6.30 g 63.02 g/mol = 0.0999…mol pH = -log[H+(aq)] = -log[0.133… mol/L] = 0.875 c = n V = 0.0999…mol 0.750 L = 0.133…mol/L

just as deals with deals with pH [H3O+(aq)], pOH [OH(aq)] ***p just means log at SATP… pH + pOH = 14 pH 1 3 5 7 9 11 13 14 14 13 11 9 7 5 3 1 pOH

to calculate the use the same formulas as pH but substitute the pOH, [OH(aq)] pOH =  log[OH(aq)] Try These: 1.     [OH(aq)] = 1.0  10-11 mol/L pOH = 2.     [OH(aq)] = 6.22  10-2 mol/L pOH = 3.     [OH(aq)] = 9.411  10-6 mol/L pOH = 4.     [OH(aq)] = 2  10-6 mol/L pOH = 11.00 1.206 5.0264 5.7

you could also be given the pH or pOH and asked to calculate the [H3O+(aq)] or [OH-(aq)] [H3O+(aq)] = 10-pH [OH(aq)]= 10-pOH

Try These: 1.     pH 4.0 [H3O+(aq)] = 2.     pH 6.21 [H3O+(aq)] = 3.     pH 13.400 [H3O+(aq)] = 4.     pH 7 [H3O+(aq)] = 5.     pOH 1.0 [OH(aq)] = 6.     pOH 13.2 [OH(aq)] = 7.     pOH 6.90 [OH(aq)] = 8.     pOH 0.786 [OH(aq)] = 1 x 10-4 mol/L 6.2 x 10-7 mol/L 3.98 x 10-14 mol/L 10-7 mol/L 0.1 mol/L 6  10-14 mol/L 1.3  10-7 mol/L 0.164 mol/L

9. Complete the following table: [H3O+(aq)] [OH(aq)] pH pOH Acid/Base/ Neutral 4.0 x 10-6 mol/L 2.5 x 10-9 mol/L 5.40 8.60 acid 9.500 4.500 base 3.16 x 10-10 mol/L 3.16 x 10-5 mol/L 3.30 10.70 5.0 x 10-4 mol/L 2.0  1011 mol/L acid 10 mol/L 1.0 x 10-15 mol/L -1.00 15.00 acid base 1.0 x 10-15 mol/L 10 mol/L 15.00 -1.00 1.36 base 2.3 x 10-13 mol/L 0.044 mol/L 12.64

D. Measuring pH Indicators pH can be measured using : 1. acid-base indicators 2. pH meter Indicators an is any chemical that in an acidic or basic solution acid-base indicator changes colour they can be dried onto strips of paper eg) litmus paper, pH paper

they can be solutions eg) bromothymol blue, universal indicator, indigo carmine etc they can be made from natural substances eg) tea, red cabbage juice, grape juice

each indicator has a where it will specific pH range change colour you can use to approximate the two or more indicators pH of a solution

pH Meters using a pH meter is the most way of measuring precise pH it has an that compares the [H3O+(aq)] in the solution to a and it will give a of the pH electrode standard digital readout

E. Diluting an Acid or Base when you to an , you change the add water acid or base [H3O+(aq)] or the [OH(aq)] diluting an acid will the until a pH of is reached decrease [H3O+(aq)] 7.0 diluting a base will the until a pH of is reached decrease [OH-(aq)] 7.0

Remember: CiVi = CfVf A concentrated solution is made by dissolving 5g of HCl into 30 L of water. You then take 10 mL of this solution and dilute it to a volume of 50 L. What is the pH of the diluted solution?

Formulas to remember: pH = - log [H3O+] pOH = - log [OH-] [H3O+] = 10-pH [OH-] = 10-pOH C = n/v CiVi = CfVf

Review Assignment: Textbook p. 244 #1-28