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Naming AcidsWhat makes an acidunique and how are acids named?

whv?A variety of acids are used in foods, induslry and research. Acids are covalently bonded molecules, butwhen they are put into water they produce ions. One of the ions produced is always H*, which immedi-ately combines with a water molecule to form the hydronium ion (HrO ). The HrO * ion is what definesthe acidic properties of a substance. Because oftheir special classification, acids have a naming systemdifferent from ionic or other molecular (covalent) compounds.

*Hydrogen ions (H*) join with water molecules in solutionto form hydronium ions, H p-.

1. Complete the cation arid anion columns of the table in Model 1. Be careful to show the charges

on the ions.

2. Why does hydrosulfuric acid contain two hydrogens?

VrtW be^ce*se s.r.\$.ar has a3. Look at the formulas and names ofthe binary acids in Model 1.

a. What prefix i5 used at the beginning ofthe name for all binary acids?

hld.ro -b. What suffix is'used at the end ofthe name for all binary acids?

-ic'ek'4. The prefix o'bl' means 'otwo." Propose a reason that the acids in Model I are all referred to as

"binary''acids.conta,q *uso \e"S of e\ecq<x.,f6

im% S. Write a rule fornaming binary acids.

m\ls+ 6o.,\c,\r n hqdvoryn ond :* ct\tn€r

\p" oF ele-rrrant

Z- charte

Model 1-BinaryAcids

AcidName of acid inaqueous solution

Cation (+)* Anion(-)

HCl Hydrochloric acid Hro* cl'HBr Hydrobromicacid F{.ro" b.''H,S Hydrosulfuric acid 2H30-* s2-

FIF Hydrofluoric acid H:O* Fi-

NamingAcids

Model 2 -Ternary Acids (Oxyacids)

AcidNameof Acid in

Aqueous Solution Cation(+) Polyatomic Anion(-)

Polyatomic AnionName

HCIO, Chloricacid' H.O* ClDt ch\o ra.VtH,SO, Sulfurous acid .3 H.+Ot 50 a- oafi reH7S04 Sulfuric acid {.l-tsot 3,oq'- Sulfate

H"PO, Phosphorous acid H.0 PO? Phosphite

H.PO, Phosphoric acid 3 H.sO *

PO,t- ghosPhalsHNO. Nitric acid [-[,uO. No.t- n i*roleHNO, Nitrous acid 'il.On NOrt- Nitrite

H,CO" Carbonic acid I HaO* Cos'' ea-rbonq,+e-

&, O. Write a rule for naming ternary acids.

6. Look at the formulas ofthe ternary acidsin Model2. "fa. How are ternary acids different from binary acids in their structure ?

cor*a.-rns b elerrrents (U\ , O, and crno$nor

D. What number do youthink the prefix "ter-" refers to?

*\'r''e7. When ternary acids aremixed withwater, ionswill form. Fill in the tableabove withthe

formulas and names ofthe anions.

8. Examine the pairs of ternary acids in Model 2 that contain sulfur, phosphorus, and nitrogen.Each pair has one acid that ends in "-ic" and another that ends in "-ous." These endings arerelated to the name ofthe polyatomic anion found in the acid("-ate" or o'-ite"). Completethestatements below. with the correct acid name ending.

Polyatomic anion ending is oo-ate" --- acidname ending is - t c

Polyatomic anion.ending is "-ite" --+ acidname ending is " ours

9. If the prefix "hydro-" were used to name atemary acid, what problem would this create whennamingHclo3? hqdruch\onc o-cjd \s Hcl

I 1. Predict the formula for chlorous acid.

t{c,to.12. Circle the acid(s) below that wouldbe named beginning with the prefix "hydro-."

H2so3@@H2co3HNo2

rnus+ conlo,iq H, O *d qno+hea- etemeni

POGIL'" Activities forHigh School Chemistry

Extension Questions

\-, Model3 - Halogen Oxyacid Acid Families

13. Write the formulas ofthe cations and anions for each acidin the tablein Model3.

14. Consider the names ofthe oxyacids in Model3 that contain chlorine. All halogens form similar

oxyacids that use the same naniing convention. Fill in the names ofthe halogen oxyacids to

complete the table.

15. The table below includes both binary and ternary acids. Using what you have learned in this

activity, fill in the missing formula and name for the anion in each acid, and give the formula

ofthe acid.

Acid name Anion AnionName Acid Formula

Hydroiodic acid T- iodrrre RT

Chlorous acid Nz ch\on\e- HCAO,

Hypobromouspcid 6.o" \rqeob.omilg \\BrOPhosphoric acid h+3" ohpspho*e FlnW+Sulfurous acid i,o^L- s *t$ie ll,SOr

Acid Nameof Acid Cation(+) Anion(-) AnionName

HCIO4 Perchloric acid l-{so" C\Oq - Perchlorate

HCIO3 Chloric acid H,o* c\D5- W" Ch\ora\€

HCIO2 Chlorous acid H <o" C]D,- Chlorite

HCIO Hypochlorous acid F\aO* c\o- $ypoclr\on\eHBrO, ?*b**.lfo".,d ilso* BrO.l Perbromate

HIO3 \odic ocrd H.O* W:D; \odto\eHF'O2 HrrorouS Ocrd il.O* FO,- flrr.,nfeHIO ltuipoiodoqs ar-iC LluO- IO- Hypoiodite

Naming Acids