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Chemistry Chapter 15
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1
----------- dissociate completely into ions in water
Strong ACIDS
---------- dissociate very slightly into ions in water
weak acids
Acid-dissociation constant
K
c
= ([H
3
O][A
-
])/([H
2
O][HA])
Acids get stronger as
#O's exceed #H's (H's being protons)
classify H
2
SeO
4
Strong acid - H2SeO4 - the number of O atoms exceeds the number of ionizable protons by 2.
classify (CH
3
)
2
CHCOOH
Weak acid - (CH3)2CHCOOH is an organic acid having a -COOH group.
classify KOH
Strong base - KOH is a Group 1A(1) hydroxide
classify (CH
3
)
2
CHNH
2
Weak base - (CH3)2CHNH2 has a lone pair of electrons on the N and is an amine
Acid Ionization Constant
K
a
=([H
3
O
+
][A
-
])/[HA]
How do H3O+ and OH- compare in different solutions?
acidic
pH=
-log[H
3
O
+
]
pKa=
-logKa
The larger the pKA...
the weaker the acid
Why is HCLO4 a strong acid
greater number difference between oxygen and protons (hydrogen)
pH is the –log of
the hydronium ion concentration
If you have ---------------------- you can assume x is small
a large Pa and a small Ka,
Percent HA dissociation
([HA] dissociated/[HA]initial) * 100
polyprotic acids
acids with more than (more?) ionizable proton
Remember------------- = 14
pOH + pH =14
Strong Bases
LiOH - lithium hydroxide NaOH - sodium hydroxide KOH - potassium hydroxide RbOH - rubidium hydroxide CsOH - cesium hydroxide *Ca(OH)2 - calcium hydroxide *Sr(OH)2 - strontium hydroxide *Ba(OH)2 - barium hydroxide
There are three factors that can be used to argue which acid is stronger when comparing two acids based upon their structure.
1)The bond strength of the H-X bond.
2)The polarity of the H-X bond.
3)The stability of the resulting conjugate base.
Acid strengths can not always be predicted but there are some trends that can be applied to assess acid strength.
1)Comparing acids that differ only by their charge and thenumber of protons in their formula.
2Comparing binary acids across aperiod.
3Comparing binary acids down a group.
4Comparing oxoacids thatdiffer by the central atom.
5Comparing oxoacids with the same central atombut that differ by the number of oxygen atoms in their formula.
Strong acids
HCl - hydrochloric acid
HNO3 - nitric acid
H2SO4 - sulfuric acid
HBr - hydrobromic acidHI - hydroiodic acid (also known as hydriodic acid)
HClO4 - perchloric acid
Author
zzto
ID
175701
Card Set
Chemistry Chapter 15
Description
Chapter 15
Updated
2012-10-15T12:30:55Z
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