Acids & Bases

Properties of Acids and Bases

Acids react with basesAcids are electrolytesAcids act on some metals to produce H2(g)

Acids turn litmus paper REDAcids taste SOUR.

Bases react with acidsBases are electrolytesBases feel slipperyBases turn litmus paper BLUEBases taste BITTER.

Litmus is: RE LUE

ACI ASE

The pH scale is a number scale for measuring how acidic or basic a solution is. One simple definition of acids is that they are chemical compounds that produce a solution with a pH of less than 7 when they dissolve in water. Bases are compounds that produce a solution of pH of more than 7 when they dissolve in water. If a solution has a pH of 7, it is said to be neutral (neither acidic nor basic). Notice that the “p” in pH is always lower case, and the “H” is always upper case. pH values do not have a unit of measurement written after the number.

•An INDICATOR is a weak organic acid or base with different colors for its conjugate acid and base forms. Ex :HIn + H2OIn- + H3O+

yellow red

When the indicator is in acid, the excess H3O+

shifts the equilibrium and the solution turns YELLOW.

•An indicator is in its CONJUGATE ACID form when in HIGHLY ACIDIC solutions: [HIn]>[In-] In basic solutions, the [H3O+] is very low so that

the equilibrium shifts to the In- side and the solution turns RED.•An indicator is in its CONJUGATE BASE

form when in HIGHLY BASIC solutions:[HIn]<[In-] ***Note: HIn is acid form of indicator.

In- is the conjugate base of the indicator.

                                                       

A UNIVERSAL INDICATOR is an indicator solution which changes color several times over a range of pH values.

Some Common Acids and Bases

that You Should Know Sulphuric Acid: H2S04

Hydrochloric Acid: HClNitric Acid: HNO3

Acetic Acid: CH3COOHSodium Hydroxide: NaOH

Potassium Hydroxide: KOH

Ammonia: NH3

Some work for you to try!!

• Workbook Page 84 & 85

Some Common Acids naming scheme: {H + something} Three Acids:

1. H + Non Metal (found on right side of Periodic table {Halogen})

a) start with “HYDRO b) add non metal c) change ending to IC most times {RIC}d) add word “acid”

Example: HF = hydrofluoric acid

2. H + Poly atomic ion with a ATE ending

a) name P.A.I.b) change ending to “RIC”c) add word “acid”

Example: H2SO4 = sulphuric acid

3. H + Poly atomic ion with a ITE ending

a) name P.A.Ib) change ending to “rOUS”c) add word “acid”Example: HNO2 = nitrous acid

Some more for you to try

• Work Book Pages 86 & 87

• A word equation for an acid reacting with a base might look like:

• Hydrochloric acid plus Sodium hydroxide reacts to produce salt (sodium chloride) and water.

• A skeletal equation might look like:• HCl + NaOH NaCl + H2O• In this case the skeletal is also a balanced

equation.

Net Equations:• Sometimes we are asked to write a net equation

for the reaction:• H+ + OH- H2O• The net is the acid + base water• We often refer to reaction that involves an acid &

a base as a “NEUTRALIZATION” equation, because an acid & a base have been neutralized to form water (neither acid nor base)

• Bases are often described as CAUSTIC if they are strong. Ex drain cleaner, oven cleaner

• You will be expected to identify a neutralization reaction from pieces (an incomplete equation) & add the missing pieces then balance it.

• Ex) Complete & balance the following:• A neutralization reaction with Phosphoric

Acid produced Calcium Phosphate

• Unbalanced (Skeletal):• H3PO4 + Ca(OH)2 Ca3(PO4)2 + H2O• Balanced:• 2H3PO4 + 3Ca(OH)2 Ca3(PO4)2 + 6H2O

• 1. Write a neutralization equation with sulphuric acid that produces Calcium sulphate.

• 2. What base did a student spill on themselves if they produced Aluminum acetate to help stop the reaction in their skin. Write a balanced equation to show how the product was produced.

• Many acids will only behave as an acid when they are mixed with water. For this reason acids are often written as being dissolved in water (The word Aqueous means dissolved in water), we shorten Aqueous to aq.

• Example HCl is written as HCl(aq)

• Please try the reading check From Text on:

• page 225 # 1 to 5• page 227 # 1 to 5• page 228 # 1 to 4• WB page 88, 91, & 92

BASIC ANHYDRIDEBASIC ANHYDRIDE An oxygen-containing compound that reacts with water producing a basic solution.

Metal Oxides = Metal+OxygenMetal Oxides = Metal+Oxygen when added to water produce BASICBASIC solutions.

Na2O(s)2Na+(aq)+O2-

(aq)

O2-+H2O2OHOH--

Completing the balancingCompleting the balancing: Na2O(s)+H2O2NaOHOH

ACIDIC ANHYDRIDEACIDIC ANHYDRIDE-An oxygen-containing compound that reacts with water producing an acidic solution.

NONMETAL OXIDES=NONMETAL + OXYGENNONMETAL OXIDES=NONMETAL + OXYGEN when added to water produce ACIDICACIDIC solutions.

The nonmetal oxides you should know are The nonmetal oxides you should know are the SOthe SOXX, CO, COXX and NO and NOX.X.

NOXNOX from combustion reactions such as in an automobile cause some N2 to react with O2 in the air.

N2 + O22NO 2NO+O22NO2

N2 + 2O22NO2 2NO2+H2OHNO2+HNO3

SOSOX X from coal and oil burningfrom coal and oil burning

S + O2 SO2 SO2 +H2OH2SO3

2SO2 +O22SO3 SO3 + H2OH2SO4

COCOXX from fossil fuels, etc.

CO2 + 2H2OH3O+ + HCO3-