(ASSIGNMENT TEMPLATE ENGLISH VERSION) (COVER PAGE)
HBSC2103
FACULTY OF EDUCATION AND LANGUAGES
SEMESTER SEPTEMBER / 2012HBSC 2103CHEMISTRY 1MATRICULATION NO:
700908035084001
IDENTITY CARD NO.: 700908035084
TELEPHONE NO.: 019-9542303E-MAIL
: [email protected]
LEARNING CENTRE: Petaling Jaya
1.0 INTRODUCTION
Salts play an important role in our daily life.It widely use in
food preservation, in agricultures, medicine and other uses.As an
example in the agricultures field, nitrate salt such as potassium
nitrate ( KNO3 ) , sodium nitrate (NaNO3) )and ammonium salts such
as ammonium sulphate ( NH4)3SO42) , ammonia nitrate ( NH4NO3 ) are
used as nitrogenous fertelizers .While salts such as copper sulfate
( CuSO4 ) , iron (11) sulphate ( FESO4 ) and mercury chloride (
HgCI ) are used as pesticides.In the medication field , most of the
medications are made off salts. Antacid medicine contain calcium
carbonate CaCO3 and calcium hydrogen carbonate Ca (HCO3 )2 that are
used to reduce acidity in the stomachs of gasrtric patients.Another
familiar and popular examples is Panadol or paracetomol which we
use to relieve headaches and fever.Plasters of paris , used to
support fractured bones, also contain salt , calcium sulphate
CaSO4. There are various type of salt occurs in this world such as
Sodium chloride NaCl, Copper (II) carbonate CuCO3 and so on. Lead
nitrate Pb(NO3)2, lead carbonate PbCO3, potassium nitrate KNO3, and
potassium carbonate K2CO3 are several types of them.Salt is a an
ionic compound produced when the hydrogen ion H+ from an acid
replaced by a metal ion or an ammonium ion, NH4. Salt consist of
cations (positive ions) originating from base that combined with
anions (negative ions) originating from acids. The cations and the
anions of a salt are bonded by strong ionic bond.Not all salts are
soluble in water .There are soluble and non soluble salts. Soluble
salts are salts that dissolve in water at room temperature while
salts that cannot dissolve in water are called insoluble salts
.Soluble salts can be prepared in the laboratory by four method
.The four method are reaction between an acid and alkali, reaction
between acid and metal, reaction between an acid and a metal
carbonate and reaction between an acid and metal okside or
hydroxide.While insoluble salts can be prepared by precipitation in
a double decomposition reaction.In the precipition method , an
insoluble salt is precipitated when two aqueous solutions
containing the cations and the anions are mixed together.The
precipitate is then obtain by filteration.2.0 4 TYPES OF
SUBSTANCES.2.1Lead nitrate Pb(NO3)2Lead nitrate also known in IUPAC
name as lead (II) nitrate. Lead nitrate is water soluble salt with
it solubility in water is about 52g/100mL at 20 Degree Celsius. It
forms a colourless solution when dissolved in water. It is also an
inorganic compound compose of nitric acid and lead. The chemical
formula for lead nitrate is Pb(NO3)2. Normally lead nitrate occurs
as colourless crystal, or white powder. Other name for lead nitrate
is plumbous nitrate, lead dinitrate, and plumb dulcis. Lead (II)
nitrate also known as a toxic salt, harmful and dangerous to
environment. Besides that, lead (II) nitrate also is an oxidizing
agent, and is categorized as probably carcinogenic to human by
International Agency for Research on Cancer. So lead (II) nitrate
must be handled and stored with the appropriate safety precautions.
It is important to avoid inhalation, ingestion and skin contact.
Normally lead (II) nitrate does not occur naturally. It can be
obtained by dissolving metallic lead in an aqueous nitric
acid.2.2Lead carbonate PbCO3
Lead carbonate composed of lead and carbonic acid. Unlike lead
nitrate, lead carbonate is insoluble salt. It solubility in water
is about 0.00011g/100mL. It is also known as crussite and become a
popular collection of mineral. Molecular formula for this salt is
PbCO3. Lead carbonate, PbCO3 occurs as white powder at 20 Degree
Celsius and melting at 315 Degree Celsius. Lead carbonate PbCO3 is
also insoluble in alcohol but it is soluble in acids and alkaline.
Lead carbonate PbCO3 prepared industrially from lead (II) acetate
and carbon dioxide by passing carbon dioxide into a cold dilute
solution of lead (II) acetate.
2.3Potassium nitrate KNO3Potassium nitrate is also known as
saltpeter or nitrate of potash. It is an ionic salt of potassium
ions, K+ and nitrate ions, NO3-. The chemical formula for this salt
is KNO3 and its molecular mass is about 101.1032g/mol. Potassium
nitrate appears in white solid and only melting at 334 Degree
Celsius. It is odorless and soluble in water. It solubility in
water is about 383g/L at 25 Degree Celsius. It is slightly soluble
in ethanol and also soluble in glycerol and ammonia. Potassium
nitrate KNO3 is harmful if swallowed, inhaled or absorbed on skin.
It will cause irritation to skin and eyes area. Potassium nitrate,
KNO3 is highly used in fertilizer, food additive, fireworks and
rockets propellants. Combination of ammonium nitrate and potassium
hydroxide will produced potassium nitrate. This is shown by the
equation: NH4NO3(aq) + KOH (aq) NH3(g) + KNO3(aq) + H2O (l)
ammonium nitrate (aqueous) + potassium hydroxide (aqueous)
ammonia(gases)+ potassium nitrate (aqueous) + water (liquid)
2.4Potassium carbonate K2CO3Potassium carbonate is a white salt
which is soluble in water but in soluble in alcohol and acetone.
When dissolve in water, potassium carbonate will form a strong
alkaline solution. Other names for potassium carbonate K2CO3 are
potash and pearl ash. Molar mass for potassium carbonate, K2CO3 is
about 138.205g/mol with density 2.29g/cm3. The absorbance reaction
between potassium hydroxide KOH and carbon dioxide CO2 will produce
potassium carbonate, K2CO3. Usually potassium carbonate is used in
production of glass and soap. 3.0HOW TO IDENTIFIED AND FIND OUT THE
SUBSTANCEThe given substance can be indentified using the
Qualitative Analysis. Qualitative analysis is a chemical methods or
technique to determine the substances present in a compound through
certain chemical test. The cation and anion in salt normally can be
identified through: The technique of qualitative analysis includes
.i) Colour and solubility of the salt ii) Confirmatory test for
anioniii) Confirmatory test for cationiv) Gas testv) Effect of heat
on salt 3.1Identified The Colour and Solubility Of The SaltThe
colour of the salt can be identified by observation. As the colour
of lead nitrate, Pb(NO2)3, lead carbonate, PbCO3 , potassium
nitrate, KNO3, and potassium carbonate, K2CO3, are same in colour,
it is difficult to differentiate between them. So, the next test is
test for the solubility of the salt.The apparatus needed to carry
out this test are test tubes, glass rods, spatula and test tube
holder.The given substance is put in the test tube using a
spatula,Distilled water are added to the above test tube.The
mixture is strirred and the solubility of salt is observed. From
these four types of salt mention before, only lead carbonate,
PbCO3, is insoluble in water.So if the substance is insoluble in
the water the substance is lead carbonate, PbCO3. But, if the
substance is soluble, the salt must proceed to the other test for
identified whether it is potassium carbonate, K2CO3, potassium
nitrate, KNO3, or lead nitrate, Pb(NO2)3.3.2Confirmatory Test For
AnionAnions that are normally tested in qualitative analysis are
carbonate ions CO32, Chloride ions, Cl- , Sulphate ions, SO42, and
nitrate ions, NO3. Since, the anion present in potassium nitrate,
KNO3, lead nitrate, Pb(NO2)3, and potassium carbonate K2CO3, are
nitrate ions and carbonate ions, so the anions test is just for
carbonate ion test and nitrate ion test. The apparatus used in this
experiment are test tubes, and delivery tube with stopper. Before a
chemical test can be performed, the salt needs to be dissolved in
water first to produce an aqueous solution. The aqueous solution
then divides into two test tubes. The first test tube is used to
test the present of carbonate ions CO32-. 3.2.1Carbonate ion
test:i. About 2 cm-3 of unidentified salt solution is poured into
the test tube. Then, a little dilute hydrochloric acid, HCl, is
added into the solution. Gas that produced is passing through lime
juice. Lime juice is used to indicate the present of carbon dioxide
gases.ii. If the carbonate ions, CO3- present, the effervescence
occurs and the gas released by the salt solution will clouds the
lime juice.iii. When there is the present of carbonate ions, CO3-,
adding hydrochloric acid will produced carbon dioxide gas and
water. This is due to the hydrogen ions in hydrochloric acids
combine with oxygen from carbonate ions to produced water. The
equation is shown below:
CO32-(aq) + 2H+ (aq) C02 (g) + H2O (l)
Carbonate ions (aqoues) + 2 hydrogen ions carbon dioxide (gases)
+ water (liquid) Figure 1: Carbonate ions CO32- test.
3.2.2Nitrate ions test:
i. About 2 cm3 of unidentified salt solution is poured into a
test tubes and about 2cm3 dilute sulphuric acids then added to the
solution followed by the addition of 2cm3 of iron(II)sulphate,
FeSO4, solution. After that, several drops of concentrated
sulphuric acids, H2SO4, are added slowly into the solution. At this
time the test tube must be slant and do not shake.ii. If brown ring
form, it is shown the present of nitrate ions NO3-. If not, there
is absence of nitrate ions NO3- in the solutions.
Nitrate ions test is also known as brown ring test. Addition of
the iron(II)sulphate, FeSO4 to a solution of nitrate, and then
followed with slowly addition of concentrated sulphuric acids,
H2SO4, will form a layer below an aqueous solution. A brown ring is
form at the junction of the two layers which indicate the presence
of nitrate ions. The overall reaction is shown below:
NO3-+ 3Fe2++ 4H+ 3Fe3++ NO + 2H2O
[Fe(H2O)6]2++ NO [Fe(H2O)5(NO)]2++ H2O
This reaction shows reductionof the nitrate ion by iron (II)
which is oxidized to iron(III) and formation of a nitrosonium
complex.
Figure 2: Nitrate ions, NO3- test (Brown ring test).So, by using
anions test, it can shows whether there is the present of nitrate
ions NO3- or carbonate ions CO32- in the unidentified salt
solution. If carbonate ions, CO32- , is present, the salt is
potassium carbonate. But if nitrate ions NO3-, is present in the
unidentified salt solution, it is either potassium nitrate, KNO3,
or lead nitrate Pb(NO3)2 . To shows whether it potassium nitrate,
KNO3, or lead nitrate, Pb(NO3)2, conformation test for cation must
be done.3.3Confirmatory Test For Cation.Normally in solid form,
cation can be classified into coloured cation and white cation. The
same as test for anions, test for cation also needs the salt to be
dissolved in water to form aqueous solution. In an aqueous solution
the cation can be divide into two, one is colourless aqueous cation
solution and the other one is coloured aqueous cation solutions.
Colour blue indicate the present of copper, CU2+, Green for the
present of FE2+ and Brown showed the present of Fe3+. For the
present of cation such as lead Pb2+ , zinc Zn2+, calcium Ca2+, and
so on, the solution is colourless. As in this laboratory test, we
have to differentiate between potassium nitrate and lead nitrate,
the cation test is just to test the present of lead ions Pb2+.
To test the present of lead ions, test tube and sodium hydroxide
NaOH solutions is needed. First, 1cm3 of unidentified salt solution
is poured into test tube. Then, sodium hydroxide, NaOH solution is
added drop by drop until excess while shaking it. If the present of
lead ions Pb2+, the white precipitate is occurs when sodium
hydroxide NaOH is added and the white precipitated then soluble in
access of sodium hydroxide NaOH. The present of lead ions will
shows that the salt is lead nitrate, Pb(NO3)2 but if the salt
solutions shows the absent of the lead ions, it is potassium
nitrate KNO3.
Figure 3: Test for cation Pb2+3.4Effect of Heat On Nitrate Salt
and Carbonate Salt
3.4.1Effect Of Heat On Nitrat
Heating test on salt also can be done to identified either it is
nitrate salt or carbonate salt .All ammonium , carbonate , nitrate
and some sulphates salts will decomposed when heated.All ammonium
salts liberate ammonia gas when heated.All carbonates except
potassium carbonate and sodium carbonate produce carbon diokside
gas when heated .To test the effet off heat on carbonate salts the
exsperimen below can be carried out.Apparatus : Boiling tube, test
tube , test tube holder , delivery tube with rubber stopper ,
spatula and Bunsen burner.
Materials : Potasium carbonate and lead (11) carbonate or an
known substance given and lime water.
Prosedure
1. One spatula of substance is placed in dry boiling tube and
the colour of solid is recorded.
2. The boiling tube is fitted with a stopper with a delivery
tube.
3. The carbonate salt is heated slowly and then strongly.
4. Any gas evolved is passed through the delivery tube into the
lime water.The effect of lime water is recorded
5. When there is no further change .The colour of residue when
it is hot is recorded.The colour of residue when it is cold to room
temperature is also recorded.6. The experiment is set up as shown
in figure 4.
Figure 4 Heating test on carbonate salts
Result
Carbonate SaltColour Of Salt before heatingCalour of
residueEffect on limewater
When hotWhen cold
Pottassium Caobonate,K2CO3whitewhitewhiteNo visible change
Lead(11) carbonate, PbCO3
whitebrownyellowLimewater turn milky
DiscussionWhen lead carbonate is heated , Lead (11 ) oxide and
carbon dioxide gas are produced.
PbCO3(s ) PbO(S) + CO2(g)Lead (11) oxide is brown when hot and
yellow when cool
ConclusionPotassium carbonate will not decomposed on heating ,So
only Lead(11) carbonate is decomposed to lead (11) okside and
carbon dioxide gas which milky the limewater.So the substances are
lead (11) carbonate.3.4.2Effect of heat on nitrate saltAll nitrate
decomposed when heated. Nitrate salts will produced oxygen gas ,
nitrogen dioxide gas and metal oksides when heated .To identify the
the nitrate substance we can carried out an experiment given
below.Apparatus
Boilong tubes, litmus paper , test tube holder, woodent splint ,
spatula and Bunsen burner
MaterialNitrate salt
Procedure
1. One spatula of nitrate is placed in dry boiling tube and the
colour of solid is noted.
2. The boiling tube is fitted with a stopper with a delivery
tube.
3. The nitrate salt is heated slowly and then strongly.
4. Any gas evolved is tested by a glowing wooden splint ( Figure
6 a ) and moist blue litmus paper ( Figure 6 b ) .The result are
recorded.
5. When there is no further change,.the colour of residue is
recorded when it is hot .The colour of residue is recorded again
when the residue is cooled to room temperature .If the salts are
nitare the result as followed
\
Figure 6(a ) and 6 (b)
Result
SaltColour of salt before heatingColour of residueTest on
gas
When
hotWhen
coldColour of gasEffect on glowing wooden splintEffect on moist
blue
Litmus paper
Potassium nitrate, KNO3whitewhitewhiteColourlessRekindlesNo
Change
Lead Pb(NO3)2.whitebrownyellowbrownRekindlesTurn Red
DiscussionThe brown gas that changed moist blue litmus paper to
red is nitrogen dioxside gas.The gas that rekindles a glowing
wooden block splint is oxygen gas.ConclusionAll nitrate salt
decomposed on heating.Potassium nitrate and plumbum nitrate
decomposed to oxygen when heated .If the result as above the
substances are nitrate salt
4KNO3(s) 2K2O(s) + 2N2(g) + 5O2(g)
2 Pb(NO3)2(s) 2 PbO (s) + 4 NO2(g) + O2(g)4.0Method To Prepared
Lead Carbonate PbCO3Lead carbonate is an insoluble salt. The
formula for lead carbonate is PbCO3 and usually this salt is also
known as Cerussite. Usually present in colourless or white, also
yellow, grey and even blue green. One properties of this salt is it
is very soluble in acid or alkali but insoluble in alcohol or
ammonia while it solubility in water is about 0.00011g/100Ml at 20
Degree Celsius. This salt can be prepared through precipitation
reaction or known as double decomposition reaction. Double
decomposition reaction is the reaction normally used to prepare
insoluble salt such as lead carbonate PbCO3, lead sulfate PbSO4,
lead chloride PbCl2, zinc carbonate ZnCO3, silver chloride AgCl,
and so on. This reaction involves the exchange of ions to produce
insoluble salt by mixing the aqueous solution that containing the
ion of the insoluble salt that to be formed. This reaction can be
shown as:A-B + C-D A-C + B-D
So, to produce PbCO3, the soluble salt can be used are lead
nitrate Pb(NO3)2 and potassium carbonate KCO3. To produce 1mol of
lead carbonate PbCO3, 1 mol of lead nitrate Pb(NO3)2 and 1 mol of
potassium carbonate KCO3 needed. This is due to the chemical
equation:
Pb(NO3)2 + KCO3 PbCO3 + 2KNO3
The equation shows that 1 mol of lead nitrate Pb(NO3)2 react
with 1 mol of potassium carbonate KCO3 will produce 1 mol of lead
carbonate PbCO3 and 2 mol of potassium nitrate KNO3. Before started
this reaction, the materials needs are 1 mol dm-3 of potassium
carbonate KCO3 and 1mol dm-3 lead nitrate Pb(NO3)2. Apparatus used
in this laboratory activity are two of 250cm3 beakers, glass rod,
filter paper, and filter funnel. Then, 50cm3 of 1mol dm-3 of lead
nitrate Pb(NO3)2 is added to the same amount of 1 mol dm-3 of
potassium carbonate KCO3 in a beaker. The mixture then stirred by
using glass rod for about two or three minutes. After that, leave
the mixture for a while, and you will see the precipitated are
formed. This precipitated is lead carbonate PbCO3
precipitation.
The next step is filtered the mixture with filtered paper. By
using the filter paper, lead carbonate PbCO3 precipitate can be
separate from potassium nitrate KNO3 .The salt crystal or lead
carbonate precipitation then will stick at the filter paper while
the soluble salt potassium nitrate will go through the filter
paper. A small amount of distilled water then used to rinse the
salt. This is to make sure the access of potassium nitrate KNO3
will be removed from the lead carbonate PbCO3 precipitated. Lead
carbonate precipitated then dried under the sunlight or using
microwave. The dried lead carbonate then is able to be used.
From this double decomposition reaction, precipitation that
occurs between lead nitrate and lead carbonate solution is:
Pb(NO3)2 (aq) + KCO3 (aq) PbCO3 (s) + 2KNO3 (aq)
This precipitated reaction also can be represent in ionic
equation as:
Pb2+ (aq) + CO32- (aq) PbCO3 (s)
Lead ion (aqueous solution) + Carbonate ion (aqueous solution)
lead carbonate (solid)
Figure 7 : Preparation of insoluble salt lead carbonate PbCO3For
the conclusion, PbCO3 can be prepared through double decomposition
reaction between lead nitrate Pb(NO3)2 and potassium carbonate KCO3
solutions. Lead ions Pb2+ will combine with carbonate ions CO32- to
produce solid lead carbonate PbCO3.
3125 wordsReferences
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Pearson Longman.2. Tan Yin Toon, Loh wai and Tan On Tin (2012 )
Success Chemistry SPM.Selangor:Oxford Fajar Sdn Bhd.
3. Dr Tan Juat Ngoh, Dr Asha Kumarai Chunnu Lal and Zulkefli
Daud ( 2012 ) HBSC2103 CHEMISTRY 1, Selangor.Meteor Doc.4.
http://en.wikipedia.org/wiki/Lead(II)_nitrate5.
http://answers.yahoo.com/question/index?qid=20081118002025AAKz0Pp6.
http://cameochemicals.noaa.gov/chemical/37427.
http://www.gravitaindia.com/leadnitrate.html8.
http://en.wikipedia.org/wiki/Lead_carbonate9.
http://www.galleries.com/Cerussite10.
http://en.wikipedia.org/wiki/Potassium_nitrate11.
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Substance
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