2. Chapter 4 “Chemical Names and Formulas” Modified and adapted from Pre-AP Chemistry Charles Page High School Stephen L. Cotton H2OH2O

3. Section 4.4 Naming and Writing Formulas for Acids and Bases l OBJECTIVES: –Apply three rules for naming acids.

4. Section 4.4 Naming and Writing Formulas for Acids and Bases l OBJECTIVES: –Apply the rules in reverse to write formulas of acids.

5. Section 4.4 Naming and Writing Formulas for Acids and Bases l OBJECTIVES: –Apply the rules for naming bases.

6. Acids are… l Compounds that give off hydrogen ions (H 1+ ) when dissolved in water (the Arrhenius definition) l Will start the formula with H. l There will always be some Hydrogen next to an anion. l The anion determines the name.

7. Acids  Acids are ionic compounds (cation + anion)  H + is the cation  All acids start with H  When acids dissolve into ion pairs, they produce H +  HCl  H + + Cl -  HNO 3  H + + NO 3 -

8. Acids l Binary Acid (w/out oxygen) –composed of H & a monatomic anion –written as “hydro-(name of anion)-ic acid” l OxyAcids (w/ oxy.) –composed of H & an oygen containing anion –written as “(name polyatomic anion) -ic acid”

9. Rules for Naming acids: Name it as a normal compound first 1) If the anion attached to hydrogen ends in -ide, put the prefix hydro- and change -ide to -ic acid HCl - hydrogen ion and chloride ion = hydrochloric acid H 2 S hydrogen ion and sulfide ion = hydrosulfuric acid

10. Naming Acids If the anion has oxygen in it, then it ends in -ate or -ite 2)change the suffix -ate to -ic acid (use no prefix) Example: HNO 3 Hydrogen and nitrate ions = Nitric acid 3)change the suffix -ite to -ous acid (use no prefix) Example: HNO 2 Hydrogen and nitrite ions = Nitrous acid

11. Naming Acids Normal ending ____-ide ____-ate ____-ite Acid name is… hydro-___-ic acid _____-ic acid _____-ous acid

12. 2 additional rules (not mentioned in the book) 4) If the acid has 1 more oxygen than the –ic acid, add the prefix per- a. HClO 3 (Hydrogen Chlorate) is chloric acid b. HClO 4 would be perchloric acid 5) If there is 1 less oxygen than the -ous acid, add the prefix hypo- HClO 2 (Hydrogen Chlorite) is chlorous acid, then HClO would be hypochlorous acid

13. Remember; When Naming Acids …. l When the anion ends in —ide, the acid name begins with the prefix hydro- & the —ide changes to —ic followed by the word acid. HCl = hydrochloric acid. l When the anion ends in —ite, the —ite changes to —ous, followed by the word acid. HClO 2 = Chlorous acid. l When the anion ends in —ate, the —ate changes to —ic, followed by the word acid. HClO 3 = Chloric acid

14. Practice Naming Acids FormulaAnion Name Name H2SH2S H 2 SO 4 H 2 SO 3

15. Practice Naming Acids FormulaAnion Name Name H2SH2SSulfide H 2 SO 4 Sulfate H 2 SO 3 Sulfite

16. Practice Naming Acids FormulaAnion Name Name H2SH2SSulfide Hydrosulfuric Acid H 2 SO 4 SulfateSulfuric Acid H 2 SO 3 SulfiteSulfurous Acid

17. Practice by naming these: l HF lH3PlH3P l H 2 SO 4 l H 2 SO 3 l HCN l H 2 CO 3

18. Answers l Hydrofluoric Acid l Hydrophosphoric Acid l Sulfuric Acid l Sulfurous Acid l Hydrocyanic Acid l Carbonic Acid

19. PxQy Binary Acid -use “Hydro-” & “-ic” Oxy-Acid “-ate -> -ic” “-ite -> -ous” Acid Compound No Yes P=H? Does anion contain oxygen?

20. Writing Acid Formulas – in reverse! Hydrogen will be listed first The name will tell you the anion Be sure the charges cancel out. Starts with prefix hydro?- there is no oxygen, -ide ending for anion no prefix hydro? 1) -ate anion comes from –ic ending 2) -ite anion comes from –ous ending

21. Write the Formula NameCationAnionFormula Hydroiodic Acid Nitric Acid Nitrous Acid

22. Write the Formula NameCationAnionFormula Hydroiodic Acid H+H+ I-I- Nitric AcidH+H+ NO 3 - Nitrous Acid H+H+ NO 2 -

23. Write the Formula NameCationAnionFormula Hydroiodic Acid H+H+ I-I- HI Nitric AcidH+H+ NO 3 - HNO 3 Nitrous Acid H+H+ NO 2 - HNO 2

24. Write formulas for these: l hydroiodic acid l acetic acid l carbonic acid l phosphorous acid l hydrobromic acid

25. Answers l HCl l HCH 3 COO or CH 3 COOH l H 2 CO 3 l H 3 PO 4 l HBr

26. Names and Formulas for Bases l A base is an ionic compound that produces hydroxide ions (OH 1- ) when dissolved in water (the Arrhenius definition) l Bases are named the same way as other ionic compounds: –The name of the cation (which is a metal) is followed by the name of the anion (which will be hydroxide).

27. Names and Formulas for Bases l NaOH is sodium hydroxide l Ca(OH) 2 is calcium hydroxide l To write the formula: 1)Write the symbol for the metal cation 2)followed by the formula for the hydroxide ion (OH 1- ) 3)then use the criss-cross method to balance the charges.

28. Practice by writing the formula for the following: l Magnesium hydroxide l Iron (III) hydroxide l Zinc hydroxide

29. Answers l Mg(OH) 2 l Fe(OH) 3 l Zn(OH) 2