Acids Bases Properties of Acids and Bases Acids

Acids & Bases

Properties of Acids and Bases Acids react with bases Acids are electrolytes Acids act on some metals to produce H 2(g) Acids turn litmus paper RED Acids taste SOUR. Bases react with acids Bases are electrolytes Bases feel slippery Bases turn litmus paper BLUE Bases taste BITTER.

Litmus is: RE LUE ACI ASE

The p. H 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 p. H of less than 7 when they dissolve in water. Bases are compounds that produce a solution of p. H of more than 7 when they dissolve in water. If a solution has a p. H of 7, it is said to be neutral (neither acidic nor basic). Notice that the “p” in p. H is always lower case, and the “H” is always upper case. p. H 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 + H 2 O In- + H 3 O+ • An indicator is in its CONJUGATE ACID yellow red form when in HIGHLY ACIDIC solutions: + When the indicator is in acid, the excess H O 3 [HIn]>[In-] + In basic the and [H 3 Othe ] issolution very low so that shifts thesolutions, equilibrium turns the equilibrium shifts to the In- side and the YELLOW. • An indicator is insolution its CONJUGATE turns RED. BASE form when in HIGHLY BASIC ***Note: HIn is acid form of indicator. solutions: [HIn]<[In-] In- is the conjugate base of the indicator.

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

Some Common Acids and Bases that You Should Know Sulphuric Acid: H 2 S 04 Hydrochloric Acid: HCl Nitric Acid: HNO 3 Acetic Acid: CH 3 COOH Sodium Hydroxide: Na. OH Potassium Hydroxide: KOH Ammonia: NH 3

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) b) c) d) start with “HYDRO add non metal change ending to IC most times {RIC} 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: H 2 SO 4 = sulphuric acid 3. H + Poly atomic ion with a ITE ending a) name P. A. I b) change ending to “r. OUS” c) add word “acid” Example: HNO 2 = 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 + Na. OH Na. Cl + H 2 O • 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- H 2 O • 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): H 3 PO 4 + Ca(OH)2 Ca 3(PO 4)2 + H 2 O Balanced: 2 H 3 PO 4 + 3 Ca(OH)2 Ca 3(PO 4)2 + 6 H 2 O

• 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 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 ANHYDRIDE An oxygen-containing compound that reacts with water producing a basic solution. Metal Oxides = Metal+Oxygen when added to water produce BASIC solutions. Na 2 O(s) 2 Na+(aq)+O 2 -(aq) O 2 -+H 2 O 2 OHCompleting the balancing: balancing Na 2 O(s)+H 2 O 2 Na. OH

ACIDIC ANHYDRIDE-An oxygen-containing compound that reacts ANHYDRIDE with water producing an acidic solution. NONMETAL OXIDES=NONMETAL + OXYGEN when added to water produce ACIDIC solutions.

The nonmetal oxides you should know are the SOX, COX and NOX.

NOX from combustion reactions such as in an automobile cause some N 2 to react with O 2 in the air. N 2 + O 2 2 NO N 2 + 2 O 2 2 NO+O 2 2 NO 2+H 2 O HNO 2+HNO 3 SOX from coal and oil burning S + O 2 SO 2 +H 2 O H 2 SO 3 2 SO 2 +O 2 2 SO 3 + H 2 O H 2 SO 4 COX from fossil fuels, etc. CO 2 + 2 H 2 O H 3 O+ + HCO 3 -