Identifying acids, bases and salts from their molecular formulas ACID S BASES SALTS

 Allows one to determine the nature of the compound  Deals with letters/symbols from the periodic table to describe substances instead of words EXAMPLE: Acids, bases and salts all have their own rules to follow when constructing their molecular formulas CO 2 = carbon dioxide O 2 = oxygen NaCl = sodium chloride Molecular formulas Words Molecular Formulas

**If formula ends in “COOH”……ex. CH 3 COOH it is also an acid - COOH at the end of formula are called “organic acids”  Usually begins with the letter “H” (hydrogen)  Usually combines with a nonmetal or a group of atoms (ex. SO 4, ClO 4 ) ACIDS Exception The Rules….. HCl HS HF HNO 3 H 2 SO 4

CH 3 CH 4 C & H only – are NOT acids!!! C 8 H 18 C3H8C3H8

CH 3 CH 4 C3H8C3H8 ACIDSEXCEPTIONS (misleading solutions) HNO 3 H 3 PO 4 HCl Examples NOTE: any “H” combined with carbon by itself is usually an exception and not considered an acid (called hydrocarbons)

TESTERS: Where do you think these solutions belong? CLICK ENTER FOR THE CORRECT ANSWER ACIDShydrocarbons 1. HNO 3 6. H 2 SO 4 2. C 4 H 8 3. HBr 4. CH 3 5. C 3 H 8

 Usually ends with an OH  Usually combines with a metal or a NH 4 group BASES The Rules….. NaOH KOH Mg(OH) 2 LiOH NH 3

CH 3 OH C 2 H 4 (OH) 2 Alcohols – are NOT bases!!! C2H5OHC2H5OH **When OH is found at the end of the formula but attached to a carbon and hydrogen it is an alcohol

C 2 H 5 OH CH 3 OH CH 3 COOH BASESEXCEPTIONS (misleading solutions) NaOH LiOH Mg(OH) 2 NOTE: any “OH” combined with a carbon and a hydrogen together is an alcohol Examples

***salts are formed during the neutralization of an acid with a base*** SALTS The Rules….. NaCl KI K 3 PO 4 LiBr  Salt formulas neither start with H nor end with OH  Generally begin with a metal and end with a nonmetal or a group of atoms

PCl 3 2 non-metals are NOT salts!!! CCl 4 CF 4 CO 2 Covalently Bonded Compounds

PCl 3 CCl 4 SALTSEXCEPTIONS (misleading solutions) MgCl 2 NH 4 Cl KI NOTE: these exceptions just have to be memorized Examples

TESTERS: Where do you think these solutions belong? ACIDSBASESSALTS 1. H 3 PO 4 6. KOH 2. C 8 H Ca(OH) 2 4. HI 5. MgCl 2

Which of the following substances is a base? a.LiCl b.CH 3 OH c.KOH d.HNO 3 Be careful – CH 3 OH is an alcohol

Which of the following substances is a salt? a.HCl b.Mg(OH) 2 c.CF 4 d.CaF 2 Be careful – CF 4 is made from 2 non-metals, so it is NOT a salt

Which of the following substances is are acids? 1.HCl 2.CH 3 COOH 3.KOH 4.H 2 CO 3 5.C 2 H 6 6.Na 2 SO 4 7.NH 3 8.HF Be careful! This is vinegar or acetic acid!

You are given three substances & asked to classify their nature in the table below. Which table correctly identifies the nature of each substance? NatureSubstance ?MgCl 2 ?HBr ?NaOH NatureSubstance AcidMgCl 2 SaltHBr BaseNaOH NatureSubstance SaltMgCl 2 BaseHBr AcidNaOH NatureSubstance SaltMgCl 2 AcidHBr BaseNaOH

ACIDS: -common in foods (enhance flavors and preserve food) -medications BASES: -used in fertilizers, pulp and paper, plastics and food industry -processing of chemical products -common in household cleaning products -extremely important in soaps and detergents as it dissolves grease SALTS: -used in dyes -changes physical properties by lowering freezing or melting point (ex. salt on our roads to melt ice) Roles of Acids, Bases & Salts

 Acids usually begin with H  Bases usually end with OH  Salts begin with a metal & end with either a non-metal or group  Exceptions: CH 3 COOH is an acid (vinegar) A formula with only C & H are not acids, bases or salts (hydrocarbons) A formula with only C & H, ending with OH are not bases (alcohols) NH 3 is a base (ammonia) A formula with 2 non-metals are not salts (ex. PCl 3 )

 Worksheet #2  Study guide Module 3, page 4-5  Text Book -page 323 #1, #2, #6 -page 331 #3 (under exercises) -page 346 #1, #2, #3 Activities