Acids, bases & salts Revision

Properties Reactions Definition Weak Vs. Strong Common acids acids

definition A compound which produces hydrogen ions, H+, when dissolved in water Acid + H2O  H+

Strong vs weak acids Strong acids IONIZED COMPLETELY in water Weak acids IONIZED PARTIALLY in water Strong Acid Dissociate completely HCl Cl- H+ Cl- H+ Cl- H+ water

Weak acids CH3COOH Weak acid does Not dissociate completely H+ CH3COOH Ada CH3COOH Masih tetinggal CH3COOH water

Common acids Sulfuric Acid HCl H2SO4 Nitric Acid HNO3 Ethanoic Acid Hydrochloric Acid CH3COOH

Properties Taste: Sour taste Litmus paper: Blue Red

Reactions of dilute acids 1. Some METALS to give SALT and HYDROGEN gas Zn + 2HCL  ZnCl2 + H2 2. Bases to give SALT and WATER only 2NaOH + H2SO4  Na2SO4 + H2O 3. Carbonates and hydrogencarbonates (insoluble or soluble) to give salt, water and CO2 gas CaCO3 + 2HCl  CaCl2 + H2O + CO2

H+ OH- ACIDS BASES IONS THAT ARE PRODUCED!

Properties Reactions Definition Weak Vs. Strong Common bases bases

Substance which reacts with an acid to form salt and water only Definition Substance which reacts with an acid to form salt and water only NEUTRALIZATION ACIDS + BASE  SALT + WATER

REACTIONS NaOH + NH4Cl  NaCl + NH3 + H2O 1) Reacts with acids to produce salt and water only 2) Ammonium salts to produce AMMONIA NaOH + NH4Cl  NaCl + NH3 + H2O AMMONIA

Common bases CaO Copper(II) Oxide Calcium Oxide MgO Magnesium Oxide CuO Ammonia NaOH Sodium Hydroxide NH3

Then, what is an alkali Alkali are BASES THAT ARE SOLUBLE IN WATER Insoluble in water ALKALI

ALKALI PROPERTIES Slippery Turns Litmus paper: Red Blue Produces OH- when dissolved in water

Dissociation examples (remember) Alkali when dissolved in water NaOH OH- + Na+ NaOH OH- Na+ Na+ OH- OH- Na+ water

What if we try to dissolve ammonia gas? NH3 + H2O  NH4+ + OH- Do not forget OH-

Again, what is a weak alkali? Weak Alkali when dissolved in water NH3 + H2O NH4+ + OH- NH3 NH4+ OH- OH- NH4+ NH3 water

neutralization H+ + OH-  H2O In neutralization, the H+ from the ACID and the OH- from the Alkali react to form water H+ + OH-  H2O Energy Energy is being released: EXOTHERMIC

OXIDES ACIDIC OXIDES- OXIDES THAT ARE ACIDIC BASIC OXIDES- OXIDES THAT ARE BASIC AMPHOTERIC OXIDES- OXIDES THAT ARE ACIDIC AND BASIC

EXAMPLES OF OXIDES BASIC Amphoteric ACIDIC Na2O CaO Al2O3 CO2 Fe2O3 ZnO H2O CO2 SO2 P4O10 CO, NO Neutral

indicators Substances that change COLORS in acidic and alkaline solutions Litmus indicator Red Acids Blue Bases These are used in TITRATION Phenolphthalein Colorless Acids Red/Pink Base

pH scale pH is a number to show how acidic or alkaline a solution is Super acidic Getting Less basic Becoming Less acidic Super basic neutral 1 3 6 7 14 8 10 13 Very acidic Very Little acidity Very Less alkaline Very basic

Examples of neutral solution Pure Water NaCl solution Most soluble salts Ethanol solution (not ethanoic acid)

Application: PH in soil Soil can become too acidic because: Excessive use of chemical fertilizers Acid rain from air pollution by sulfur dioxide and nitrogen oxides Most plants grow well almost neutral Plants grow poorly in very high Or very low pH Soil How to fix an acidic soil?

Salts A salt is obtained from an acid when the H+ is replaced by metal ion or ammonium ion Na H Cl Acid Salt

Solubility of salts: Memorize this please Type of salts Soluble Insoluble Carbonates (NH4)2CO3 Na2CO3 K2CO3 All the rest Chlorides PbCl2 AgCl Nitrates All - Sulfates BaSO4 PbSO4 (CaSO4 is slightly soluble)

Practice Soluble Insoluble K2SO4 Na2CO3 KNO3 Pb(NO3)2 BaSO4 CuSO4 BaCO3 AgCl

How do we prepare salts???

Case 1: I want to make an insoluble salt, pbcl2 (solid) Step 1: think where PbCl2 comes from: Pb Pb2+ An aqueous solution (soluble) Pb(NO3)3 Cl2 Cl- An aqueous solution (soluble) NaCl Step: 2 Precipitation reaction Pb(NO3)2(aq) + NaCl(aq) Soluble Soluble  NaNO3(aq) + PbCl2(s) Soluble Insoluble

illustration Pb2+ Na+ NO3- PbCl2 solid Na+ NO3- Cl- Pb(NO3)2 solution NaCl solution water

Getting the salt how? FILTRATION We have solid in a liquid Na+ NO3- PbCl2 solid FILTRATION

This is how you get pbcl2

Case 2: Soluble salts 1. acid + excess metal/insoluble metal oxide/carbonate 2. acid+ alkali

How to prepare salts START NO Is the salt soluble? YES React acid with metal/alkali/metal oxide/metal carbonate Product soluble? NO YES Mix acid with excess metal/ metal oxide/metal carbonate

Work this out: I want to make copper sulfate