8 ionic precipitation

7/25/2019 8 Ionic Precipitation

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CHAPTER 8 : SALTS

IONICPRECIPITATION


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IONIC PRECIPITATE-An insoluble salt is prepared

through preipitate reation!

-In this reation" a#ueous solutionsontaining the ions o$ the insoluble

salt are %i&ed together to $or% the

salt!

-The insoluble salt $or%ed as apreipitate and an be obtained b'

$iltration!


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IONIC PRECIPITATE

-Che%ial and ioni

e#uations an be (ritten$or all reations

that are used to prepare

salts!


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E)A*PLE The $or%ation o$ preipitate o$ bariu% sulphate"

+aSO,!

Chemical reaction"

+aCl.a#/ 0 NaSO,.a#/ +aSO, .s/ 0 NaCl .a#/

+a00 Cl 0 Na00 SO,

-+aSO,

.s/ 0 Na0 0 Cl-

Ionic equations,

+a0 .a#/ 0 SO,-.a#/+aSO, .s/


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E)A*PLE -1hen a solution o$ sodiu% hloride reats

(ith sil2er nitrate!

Che%ial e#uations"NaCl .a#/ 0 AgNO3.a#/AgCl .s/ 0NaNO3.s/

Na00 Cl- 0 Ag0 0 NO-.a#/AgCl 0 Na0 0NO3-

Ioni e#uations"

Cl-.a#/ 0 Ag0 .a#/AgCl .s/


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E&eriseReactions can be represented using ionic equations.

Identify the two ionic equations that show the

neutralisation of an acid.

A. H+(aq + !H" (aq H#! (l

$. #H#! (l + !#(g +%e %!H"(aq

C. #H+ (aq + C!#"(aq H#! (l + C!#(g

&. '!#(g + H# (l #H+

(aq + #H+

(aq + '!)#"

(aq

*. H%+ (aq + !H"(aq H)(g + H#! (l
http://answer%20kimia.ppt/http://answer%20kimia.ppt/


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Constructing ionic equations

using the continuous ariation

method

- Can be used to onstrut ioni

e#uations $or the $or%ation

o$ insoluble salts!


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STEP.4/The nu%ber o$ %oles o$ ation and

anion that reat to $or% the salt is

deter%ined through ontinuous 2ariation

%ethod!

./The si%plest %ole ratio o$ ation to

anion that reat to $or% salt is

alulated!

.3/ The e%pirial $or%ula o$ the salt is

dedued!

.,/ +ased on the in$or%ation in ./" the

ioni e#uation $or the $or%ation an be

onstruted!


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E&a%ple

- cm)of .# mol dm")mercury solution

reacts completed with cm)of -. mol

dm")potassium iodide solution. A red

precipitate of mercury iodide is formed.

(aCalculate the simplest mole ratio of

mercury ions to iodide ions that reacts

with each other.

(b /hat is the empirical formula of

mercury iodide formed0


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./ 1rite do(n the ioni e#uations$or the preipitation o$ %erur'

iodide!

.d/ 1rite do(n the he%ial

e#uation $or the abo2e reation


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(aumber of moles of mercury ions in mercury

nitrate solution 1 23

1 .# ( - -

1 .# mol

umber of moles of iodide ions in potassium

iodide, 4I solution 1 23

1 -. ( -

1 . mol

Hence, the simplest mole ratio of mercury ion 5

iodide ion

1 .# 5 .1 .# 5 .

.# .#

1 - 5 #


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(b 6he empirical formula of mercury iodide is

Hg#

I.

(c 6he ionic equations for the precipitation

of mercury iodide is

Hg#+(aq + #I" HgI#(s

(d 6he chemical equation for the reaction is,

Hg(!)#(aq + #4I (aq HgI#(s +

#4!)(aq


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E&erise

cm)of -. mol dm")siler nitrate, Ag!)'olution was allowed to react completely

with magnesium chloride, 2gCl#solution to

form a siler salt.

(a /rite down the chemical and ionic

equations for the formation of siler

salt.

(b Calculate the mass of the siler saltprecipitated.

7Relatie atomic mass 5 Ag, -89 Cl, ).:

8 ionic precipitation

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