Transcript File
Identifying acids, bases and salts from their molecular formulas BASE ACID SALT Molecular Formulas Allows one to determine the nature of the compound Deals with letters/symbols from the periodic table to describe substances instead of words EXAMPLE: Molecular formulas Words Acids, bases and salts all have their own rules to follow when constructing their molecular formulas ACIDS The Rules….. Usually begins with the letter “H” (hydrogen) Usually combines with a nonmetal or a group of atoms (ex. SO4, ClO4) HS HCl HNO3 HF H2SO4 **If formula ends in “COOH”……ex. CH3COOH it is also an acid - COOH at the end of formula are called “organic acids” C3H8 CH3 CH4 C & H only – are NOT acids!!! C8H18 Examples ACIDS EXCEPTIONS (misleading solutions) HNO3 H3PO4 HCl CH3 CH4 C3H8 NOTE: any “H” combined with carbon by itself is usually an exception and not considered an acid (called hydrocarbons) ACIDS hydrocarbons TESTERS: Where do you think these solutions belong? CLICK ENTER FOR THE CORRECT ANSWER 1. HNO3 2. C4H8 3. HBr 4. CH3 5. C3H8 6. H2SO4 The Rules….. BASES Usually ends with an OH Usually combines with a metal or a NH4 group KOH NaOH LiOH Mg(OH)2 NH3 C2H5OH CH3OH C2H4(OH)2 Alcohols – are NOT bases!!! **When OH is found at the end of the formula but attached to a carbon and hydrogen it is an alcohol Examples BASES EXCEPTIONS (misleading solutions) NaOH LiOH Mg(OH)2 C2H5OH CH3OH CH3COOH NOTE: any “OH” combined with a carbon and a hydrogen together is an alcohol SALTS The Rules….. 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 KI NaCl LiBr K3PO4 ***salts are formed during the neutralization of an acid with a base*** Covalently Bonded Compounds CCl4 PCl3 CO2 2 non-metals are NOT salts!!! CF4 Examples SALTS EXCEPTIONS (misleading solutions) MgCl2 NH4Cl PCl3 CCl4 KI NOTE: these exceptions just have to be memorized ACIDS TESTERS: BASES SALTS Where do you think these solutions belong? 1. H3PO4 4. HI 2. C8H18 5. MgCl2 3. Ca(OH)2 6. KOH Which of the following substances is a base? a. LiCl b. CH3OH c. KOH d. HNO3 Be careful – CH3OH is an alcohol Which of the following substances is a salt? a. HCl Be careful – CF4 is made from 2 non-metals, so it is NOT a salt b. Mg(OH)2 c. CF4 d. CaF2 Which of the following substances is are acids? Be careful! This is vinegar or acetic acid! 1. HCl 2. CH3COOH 3. KOH 4. H2CO3 5. C2H6 6. Na2SO4 7. NH3 8. HF You are given three substances & asked to classify their nature in the table below. Nature Substance ? MgCl2 ? HBr ? NaOH Which table correctly identifies the nature of each substance? Nature Substance Nature Substance Acid MgCl2 Salt MgCl2 Salt HBr Base HBr Base NaOH Acid NaOH Nature Substance Salt MgCl2 Acid HBr Base NaOH Roles of Acids, Bases & Salts 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) Acids usually begin with H Bases usually end with OH Salts begin with a metal & end with either a non-metal or group Exceptions: CH3COOH 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) NH3 is a base (ammonia) A formula with 2 non-metals are not salts (ex. PCl3) Activities 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