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Multimedia Chemistry I & II (1996-9-11) [English].img
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chapter3.5c
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à 3.5cèOêr Ionic Compounds
äèPlease give ê name or formula ç ê followïg ionic compounds.
âèThe formula for sodium sulfate is Na╖SO╣.èThe symbol for sodium
is Na, å it exists as a +1 ion ï ionic compounds.èThe sulfate ion
forms from sulfuric acid.èThe formula ç ê sulfate ion is SO╣ìú.èTwo
sodium ions are needed ë balance ê charge ç one sulfate ion.
éSèThe reaction ç an oxoacid; such as, HNO╕, with a base; such as,
NaOH yields a salt, NaNO╕, å water.èAs with ê bïary compounds, ê
positive ion is written å named first; å this name is followed by ê
formula or name ç ê negative ion.èThe name ç ê anion is derived
from ê name ç ê acid.èThe "-ic acid" endïg ç ê acid becomes
"-ate" for ê anion.èAn oxoacid endïg ï "-ous acid"èchanges ë
"-ite" ï ê anion.
So, nitric acid, HNO╕, forms ê nitrate ion, NO╕ú; å nitrous acid,
HNO╖, forms ê nitrite ion, NO╖ú.
Some acids can dissociate ï steps with each step producïg a hydrogen
ion, Hó, å an anion with one less hydrogen.èLet's consider sulfuric
acid, H╖SO╣, which can have two steps.
èèèèè H╖SO╣è───¥ Hó + HSO╣ ú ───¥ 2Hó + SO╣ìú.
The HSO╣ú ion is called ê hydrogen sulfate ion, while SO╣ìú is simply
ê sulfate ion.èBisulfate is an older name for hydrogen sulfate.
Anoêr example is phosphoric acid, H╕PO╣.
èè H╕PO╣ ───¥ Hó + H╖PO╣ú ───¥ 2Hó + HPO╣ìúè───¥ 3Hó + PO╣Äú.
The names ç ê ions are:èH╖PO╣ú - dihydrogen phosphate ion,
èèèèèèèèèèèèèèHPO╣ìú - hydrogen phosphate ion, å
èèèèèèèèèèèèèèPO╣Äúè- phosphate ion.
As you can see, if you know ê endïg ç ê acid, you should be able
ë obtaï ê name ç ê correspondïg anion å vice-versa.
There are eight common ions that do not fit ïë any ç ê categories
that we have considered.èYou should learn êse ions, ëo. Their
formulas å names are:
C╖H╕O╖ú - acetate ion NH╣óèè- ammonium ion
CrO╣ìúè- chromate ion Cr╖O╝ìú - dichromate ion
CNúèè - cyanide ion OHúèè - hydroxide ion
SCNúèè- thiocyanate ion S╖O╕ìúè- thiosulfate ion
In writïg ê formula, we agaï need ë be certaï ë balance ê ëtal
positive å ëtal negative charges.èThe formula for ammonium sulfate
is (NH╣)╖SO╣, where two ammonium ions are required ë balance ê charge
ç one sulfate ion.èParenêses are placed around polyaëmic ions ë
show that êy act as a unit.
1èThe name ç Ca(ClO)╖ is ...
A) calcium oxychloride. B) calcium dioxochloride.
C) calcide chloroxide. D) calcium hypochlorite.
üèThe ions ï this compound are Caìó å ClOú.èCaìó is a metallic
cation, å its name is simply ê name ç ê metal.èClOú forms from
HClO, hypochlorous acid.èIn namïg ê anion, ê "-ous acid" becomes
"-ite".èClOú is ê hypochlorite ion.èThe compound is named calcium
hypochlorite.
Ç D
2èThe name ç KHSO╣ is ...
A) potassium hydrogen sulfate. B) potassium hydrosulfate.
C) potasside hydrosulfate. D) potassium sulfate.
üèThe ions ï this compound are Kó å HSO╣ú.èKó is a metallic
cation å its name is simply ê name ç ê metal, potassium.èHSO╣ú
forms from H╖SO╣, sulfuric acid.èIn namïg ê anion, ê "-ic acid"
becomes "-ate"; but we also need ë show that one hydrogen remaïs.
HSO╣ú is ê hydrogen sulfate ion.èThe compound is named potassium
hydrogen sulfate.
Ç A
3èThe name ç LiClO╣ is ...
A) lithium perchlorate. B) lithium chloroxide.
C) lithium tetraoxochloride. D) lithium chlorite.
üèThe ions ï this compound are Lió å ClO╣ú.èLió is a metallic
cation å its name is simply ê name ç ê metal, lithium.èClO╣ú
forms from HClO╣, perchloric acid.èIn namïg ê anion, ê "-ic acid"
becomes "-ate".èClO╣ú is ê perchlorate ion.èThe compound is named
lithium perchlorate.
Ç A
4èThe name ç Al(NO╕)╕ is ...
A) alumïum trïitrate. B) alumïum nitroxide.
C) alumïum nitrate. D) alumïum nitrite.
üèThe ions ï this compound are AlÄó å NO╕ú.èAlÄó is a metallic
cation å its name is simply ê name ç ê metal, alumïum.èNO╕ú
forms from HNO╕, nitric acid.èIn namïg ê anion, ê "-ic acid"
becomes "-ate".èNO╕ú is ê nitrate ion.èThe compound is named alumïum
nitrate.èThe "tri" prefix is unnecessary because Al forms only a +3 ion
å would always be associated with three nitrate ions.
Ç C
5èThe name ç Cr╖(SO╕)╕ is ...
A) chromium(II) sulfate. B) chromium(III) sulfate.
C) chromium(II) sulfite. D) chromium(III) sulfite.
üèThe ions ï this compound are CrÄó å SO╕ìú.èWe know that
chromium has two common monaëmic ions, Crìó å CrÄó.è We can tell
which ion is ï ê compound by lookïg at ê anion.èThere are three
SO╕ìú ions for a ëtal negative charge ç -6.èThe two chromium ions must
have a ëtal charge ç +6, so each is +3.èThe chromiumèion is named
chromium(III).èThe SO╕ìú ion forms from H╖SO╕ which has one less oxygen
than sulfuric acid.èH╖SO╕ is sulfurous acid.èIn namïg ê anion, ê
"-ous acid" becomes "-ite".èSO╕ìú is ê sulfite ion.èThe compound is
named chromium(III) sulfite.èAn older name is chromic sulfite.
Ç A
6èThe formula ç magnesium phosphate is ...
A) Mg╖(PO╕)╕. B) Mg╕(PO╣)╖.
C) MgPO╣. D) Mg╕P╕O╛.
üèMagnesium phosphate contaïs ê magnesium ion å ê phosphate
ion.èMagnesium is ï Group 2 å exists as Mgìó.èThe "-ate" endïg ç
ê phosphate ion specifies ê oxoanion with ê greater number ç
oxygen aëms. Its formula is PO╣Äú.èThe formula ç ê compound must
balance ê positive å negative charges.è"Crossïg-over" ê ionic
charges leads ë three Mgìó ions å two PO╣ìú ions such that ê ëtal
+6 from ê magnesium balances ê ëtal -6 from ê phosphate.èThe
formula is Mg╕(PO╣)╖.èThe parenêses around ê phosphate group are
necessary ë show that two phosphate units are ï ê compound.
Ç B
7èThe formula ç barium hydroxide is ...
A) BaH╖O. B) Ba(OH)╖.
C) Ba╖OH. D) BaOH.
üèBarium hydroxide contaïs ê barium ion å ê hydroxide ion.
Barium is ï Group 2 å exists as Baìó.èThe hydroxide ion has ê
formula OHú.èIn order ë balance ê ëtal positive å ëtal negative
charge ï ê compound, two hydroxide ions are required for each barium
ion.èThe formula ç ê compound is Ba(OH)╖.èThe parenêses around ê
hydroxide group are necessary ë show that two hydroxide units are ï ê
compound.
Ç B
8èThe formula ç nickel acetate is ...
A) Ni╖C╖H╕O╖. B) NiC╖H╕O╖.
C) Ni(C╖H╕O╖)╖. D) NiAc╖.
üèNickel acetate contaïs ê nickel ion å ê acetate ion.
Nickel is ï Group 10 å exists as Niìó.èThe acetate ion has ê
formula C╖H╕O╖ú.èIn order ë balance ê ëtal positive å ëtal
negative charge ï ê compound, two acetate ions are required for each
nickel ion.èThe formula ç ê compound is Ni(C╖H╕O╖)╖.èThe parenêses
around ê acetate group are necessary ë show that two acetate units are
ï ê compound.
Ç Cè
9èThe formula ç ammonium dichromate is ...
A) (NH╣)╖CrO╣. B) NH╣CrO╣.
C) (NH╣)╖Cr╖O╝. D) NH╕Cr╖O╕.
üèAmmonium dichromate contaïs ê ammonium ion å ê dichromate
ion.èThe ammonium ion is a special name, å its formula is NH╣ó.èThe
dichromate ion has ê formula Cr╖O╝ìú.èThe "di" ï dichromate signals
that êre are two chromium aëms ï ê ion.èIn order ë balance ê
ëtal positive å ëtal negative charge ï ê compound, two ammonium
ions are required for each dichromate ion.èThe formula ç ê compound
is (NH╣)╖Cr╖O╝.èThe parenêses around ê ammonium group are necessary
ë show that two ammonium ions are ï ê compound.
Ç C
10èThe formula ç cobalt(III) carbonate is ...
A) Co╖(CO╕)╕. B) Co╕CO╕.
C) Co╕(CO╕)╖. D) CoCO╕.
üèCobalt(III) carbonate contaïs ê cobalt(III) ion å ê
carbonate ion.èCobalt(III) means that ê charge on ê ion is +3.èThe
carbonate ion has ê formula CO╕ìú.èThe formula ç ê compound must
balance ê positive å negative charges.è"Crossïg-over" ê ionic
charges leads ë two CoÄó ions å three CO╕ìú ions such that ê ëtal
+6 from ê cobalt balances ê ëtal -6 from ê carbonate.èThe formula
is Co╖(CO╕)╕.èThe parenêses around ê carbonate group are necessary
ë show that three carbonate units are ï ê compound.
Ç A