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Naming Acids
What makes an acidunique and how are acids named?
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A variety of acids are used in foods, induslry and research. Acids are covalently bonded molecules, but
when 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 defines
the acidic properties of a substance. Because oftheir special classification, acids have a naming system
different from ionic or other molecular (covalent) compounds.
Model 1-BinaryAcids
Name of acid in
aqueous solution
Acid
HCl
Hydrochloric acid
HBr
Hydrobromicacid
H,S
Hydrosulfuric acid
FIF
Hydrofluoric acid
Anion(-)
Cation (+)*
cl'
Hro*
b.''
F{.ro"
2H30-*
s2-
H:O*
Fi-
*Hydrogen ions (H*) join with water molecules in solutionto form hydronium ions, H
1. Complete the cation arid anion columns of the table in Model
p-.
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 a
3. Look at the formulas and names ofthe binary
a. What prefix i5 used at the beginning ofthe
hld.ro b. What suffix
Z- charte
acids in Model 1.
name for all binary acids?
is'used at the end ofthe name for all binary acids?
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4.
o'bl'
means 'otwo." Propose a reason that the acids in Model
The prefix
"binary''acids.
conta,q *uso \e"S of
im
%
S. Write
NamingAcids
a
I
are all referred
e\ecq<x.,f6
rule fornaming binary acids.
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6o.,\c,\r
\p"
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n
hqdvoryn ond
ele-rrrant
:*
ct\tn€r
to as
Model 2 -Ternary Acids (Oxyacids)
Nameof Acid in
Aqueous Solution
Acid
Polyatomic Anion Polyatomic Anion
(-)
Name
Cation(+)
ch\o ra.Vt
HCIO,
Chloricacid'
H,SO,
Sulfurous acid
.3
H.+Ot
50 a-
oafi
H7S04
Sulfuric acid
3,oq'-
Sulfate
H"PO,
Phosphorous acid
{.l-tsot
H.0
PO?
Phosphite
3
PO,t-
ghosPhals
No.t-
n
H.O*
H.PO,
Phosphoric acid
HNO.
HNO,
Nitric acid
H,CO"
Carbonic acid
6. Look
a. How
*
H.sO
[-[,uO.
'il.On
Nitrous acid
at the formulas
ClDt
I
HaO*
ofthe ternary acidsin
re
i*role
NOrt-
Nitrite
Cos''
ea-rbonq,+e-
Model2.
"f
from binary acids in their structure
elerrrents (U\ O,
cor*a.-rns
are ternary acids different
and
,
b
?
crno$nor
D. What number do youthink the prefix "ter-" refers to?
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7. 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 are
related to the name ofthe polyatomic anion found in the acid("-ate" or o'-ite"). Completethe
statements below. with the correct acid name ending.
Polyatomic anion ending is oo-ate" --- acidname ending is
Polyatomic anion.ending is "-ite" --+ acidname ending
9. If the prefix "hydro-"
is " ours
were used to name atemary acid, what problem would this create when
namingHclo3?
&,
- tc
hqdruch\onc
o-cjd \s Hcl
O. Write a rule for naming ternary acids.
rnus+ conlo,iq H, O
I
*d
qno+hea- etemeni
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
POGIL'" Activities forHigh School Chemistry
Extension Questions
\-,
Model3
- Halogen Oxyacid Acid Families
Acid
Nameof Acid
Anion(-)
Cation(+)
-
AnionName
l-{so"
C\Oq
Chloric acid
H,o*
W"
HCIO2
Chlorous acid
H <o"
c\D5C]D,-
HCIO
Hypochlorous acid
F\aO*
c\o-
$ypoclr\on\e
HBrO,
?*b**.lfo".,d
ilso*
BrO.l
HIO3
\odic ocrd
H.O*
W:D;
HF'O2
HrrorouS Ocrd
il.O*
FO,-
LluO-
IO-
HCIO4
Perchloric acid
HCIO3
HIO
ltuipoiodoqs
ar-iC
Perchlorate
Ch\ora\€
Chlorite
Perbromate
\odto\e
flrr.,nfe
Hypoiodite
13. Write the formulas ofthe cations and anions for each acidin the tablein Model3.
14. Consider the names ofthe oxyacids in Model3 that contain chlorine. All halogens form similar
oxyacids that use the same naniing convention. Fill in the names ofthe halogen oxyacids to
complete the table.
15. The table below includes both binary and ternary acids. Using what you have learned in this
activity, fill in the missing formula and name for the anion in each acid, and give the formula
ofthe acid.
Acid name
Hydroiodic acid
Chlorous acid
Hypobromouspcid
Phosphoric acid
Sulfurous acid
Naming Acids
AnionName
Anion
T-
iodrrre
ch\on\e\rqeob.omilg
Nz
6.o"
h+3"
i,o^L-
ohpspho*e
s
*t$ie
Acid Formula
RT
HCAO,
\\BrO
FlnW+
ll,SOr