report scince 2 (sem 2)

8/3/2019 Report Scince 2 (SEM 2)

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SEMESTER 2 Practical Science 2

Experiment 5

Topic Qualitative analysis

Purpose To determine the cations and anions of inorganic substances

Theory Chemical analysis is the process by which we can find out the

composition of a substance by breaking it down into its

constituents. Qualitative analysis is used to find the elements

present in a given compound or mixture. Reactions of the

cations and anions with specific reagents enable its identify to

be obtained. In qualitative analysis, a chemical estimation or

assessment is usually performed on one substance at a time.

The substance in question is referred to as the "analyte." The

first step in chemical analysis is to figure out what properties

are unique to that substance such as the colour or the smell of

the substance. Any number of properties can be unique to a

substance, including but not limited to solvency (how the

substance dissolves in different solutions, as well as what it

dissolves in) and whether or not the substance absorbs or

reflects light. Once the first step of chemical testing is

completed, the scientist performing the analysis must then find

a way to identify the unique characteristics and compare the

results with other similar or contrasting results.

Apparatus Test tubes, test tube holders, test tube rack, beakers, spatula,

bunsen burner, retort stand and clamp, filter paper, filter and

glass rods.

Chemicals Solids KA 1, solid KA 2, distilled water, dilute hydrochloric acid,


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aqueous sodium hydroxide, aqueous ammonia, aqueous

ammonium chloride, aqueous iron(III) chloride, aqueous silver

nitrate, dilute nitric acid, aqueous disodium hydrogen

phosphate, aqueous potassium chromate(VI) and dilute

hydrochloric acid.

Procedure (a) Solids KA 1 and KA 2 were simple salts. The following

experiments were carried out with solid KA 1 to identify its

cation and anion.

(b) A few experiments was planned and carried out to identify

the cation and anion present in solid KA 2.

(c) In all the experiments, the reagent was added gradually

until no further change was observed. The whole

observation and deductions was recorded in table 1.0.

Deduction was made for KA 1 and KA 2. Colour changes,

precipitates, and tests on gases evolved were included in

the observations. The stage in a test where a change

occurred was indicated clearly.


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Results:

Test on KA 1

GENERAL OBSERVATION

NO. APEARANCE OBSERVATION INFERENCE

1. Colour Green - Transition

metals

element

might be

present.

- The ions

maybe Cu2+

or Fe2+

2. Smell Odourless NH4+ absence

TEST TO CONFIRM ANION AND CATION

TEST OBSERVATION INFERENCE

(d) Dilute hydrochloric acid

was added to a small

amount of solid KA 1,

and then warmed

gently.

- Effervescence

- Then, the gas was

tested with lime

water turned cloudy.

- Dark green solution

is formed after

- The gas was liberated.

-Therefore the gas is CO2

- Might be CuCl2 ,

CaCO3, Fe2+ or Ni2+


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warming.

(e) Dissolve solid KA 1 in

distilled water and

filtered. The filtrate was

separated and portions

of the filtrate were used

for tests (i) to (vi).

i. Added to aqueous

sodium hydroxide,

then in excess.

- -Not soluble in water

- Dark green

precipitate is formed

in excess

The ion maybe

- BaSO4, PbSO4,

CaSO4

- All common

chlorides (except

AgCl, HgCl,PbCl2

- All carbonates

(except Na2CO2,

K2CO2, (NH4)2CO2

- The ion may be Fe2+,

Cu2+ or Ni2+

ii. Added to aqueous

ammonia, then in

excess followed by

aqueous ammoniumchloride.

- No reaction.

- Deep blue

solution is formed

in excessaqueous

ammonium

chloride

- The presence Cu2+

was detected

iii. Added to aqueous

iron (iii) chloride then

warmed.

- Dark brown solution

is formed

- Cl- , Br- absence

- I- maybe presence

- There no any

significant different

iv. Added to aqueous

silver nitrate,

followed by dilute

- Colourless solutionformed

- When dilute nitricacid added, there

- Cl- is absence


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nitric acid. was no any change

v. Added to aqueous

disodium hydrogen

phosphate.

- Blue precipitateformed in colourlesssolution .

- Cu+ is present

- There no any

significant difference

because the ion was

dilute

vi. Added to aqueous

potassium chromate

(vi) followed by dilute

hydrochloric acid.

- Solution turned fromyellow to orangesolution

- There no any

significant difference

KA 1 is copper carbonate, CuCO3.


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Test on KA 2

GENERAL OBSERVATION

NO. APEARANCE OBSERVATION INFERENCE

1. Colour White The ion may be

Na+, K+, NH4+, Mg2+,

Ca2+, Ba2+, Al3+,

Pb2+, Zn2+

2. Smell Odourless -

TEST TO CONFIRM ANION AND CATION

Test Observation Deduction

(f) Dilute hydrochloric acid

was added to a small

amount of solid KA 2,

and then warmed

gently.

- Solution turnedcloudy

- Bubble formed

- No gas liberatedbecause there is noeffervescenceoccured

(g) Dissolve solid KA 2 in

distilled water and

filtered. The filtrate was

separated and portions

of the filtrate were used

for tests (i) to (vi).

vii. Added to aqueous

sodium hydroxide,

then in excess.

- Soluble in water

- No visible change

- White precipitate

dilute in excess

- The ion may be:- Salts of Na+, K+,

and NH4+- All nitrate salts- All common

sulphates (exceptBaSO4, PbSO4,CaSO4)

- All commonchlorides (except

AgCl, HgCl, PbCl2)- Na2CO3, K2CO3, and

(NH4)2CO3

- The ion may be Na+,K+, or no metalpresent, or thesolution is an acid.


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viii. Added to aqueous

ammonia, then in

excess followed by

aqueous ammonium

chloride.

- White gelatinousprecipitate soluble in

excess

- Ion may be present

are Al3+ , Pb2+ , Sn2+

, Zn2+

ix. Added to aqueous

iron (iii) chloride then

warmed.

- Light brown solutionis formed.

- Turned dark bownwhen warmed.

- I- , Br- , Cl- are

absence

x. Added to aqueous

silver nitrate,

followed by dilute

nitric acid.

- No reaction occured-

- Absence of ion Cl-,

Fe2+, SnO22-, SO3

2- , I-

and Br-

xi. Added to aqueous

disodium hydrogen

phosphate.

- Cloudy solutionformed

- White precipitate isformed

- Al3+ confirm present

xii. Added to aqueous

potassium chromate

(vi) followed by dilute

hydrochloric acid.

- Light orange solutionwas formed

- Turned to darkorange solution withdilute hydrochloricacid

-

- NO3- , SO4

2- and

CrO42- may be

present.

- No CO32- ion

- No significant

difference

KA 2 is Aluminium sulphate , Al2(SO4)3


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Discussions :

1. KA1 is copper carbonate CUCO3. This is proven when the gas is liberated being

tested with lime water turns cloudy when dilute hydrochloric acid is added to a

small amount of solid KA1. Therefore the gas is confirmed as carbon dioxide,

CO32- ion present. Plus, deep blue solution formed when aqueous ammonia ,

then in excess followed by aqueous ammonium chloride. Besides, blue

precipitate formed when aqueous disodium hydrogen phosphate was added to

KA1. This indicate the presence of Cu2+

2. KA2 is aluminium sulphate , Al2(SO4)3. This is confirmed when aqueous

disodium hydrogen phosphate was added into KA2 and white precipitate

formed which shows that Al3+ ion is present. Sulphate ion was proven when

aqueous potassium chromate (VI) was added to KA2 and the colour of the

solution turned from colourless to light orange in colour. The light colour

solution was then turned to dark orange when added with dilute hydrochloric

acid.

3. In certain procedures, some reaction not appeared as expected. Maybe this is

due to the old chemicals used. Besides, maybe we were doing some mistakes

while proceed the experiment, before the reaction did not completely done, we

just jump into the next procedures.Therefore, result is not very accurate.

4. Make sure not to add to many solids KA 1 or KA 2 as it may affects the results.

5. The beaker and the apparatus should be rinsed by distilled water so that no

impurities left inside them.

6. Add chemicals slowly into the solution to see the reaction occurred inside

Conclusions:

KA 1 is cooper carbonate, CuCO3

KA2 is aluminium sulphate, Al2(SO4)3


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INDIVIDUAL REFLECTION

NAME : HANANI BINTI KHARUDIN

Praise to God, because with His blessing I had finished this report on Qualitative

Analysis experiment and because of Him I could done my task successfully without any

trouble and problem. I hope my work that I had done on time will be accept by my

lecturer. During doing this experiment, I had learn many new things

During did this experiment I had learnt how to be very careful in all my actions.

For example , during took all the chemicals solution , I must be very careful so that the

solution did not spilt out because certain chemicals can cause irritation when in contact

with skin. Besides when handled all the glasses apparatus I also should be very focus

so there no those apparatus broke down and cause accident.

Furthermore , when conducted the experiment I should know the exactly things

to do so the procedures run smoothly. Somehow , there were some results did not

come out as expected. This is maybe caused by the chemicals itself. Some of the

chemicals were very old and in poor condition. Thats why the results did not appeared

very accurate. In addition, when doing this experiment, just small amount of KA1 and

KA2 were used because in large amount the reaction cannot be observed well.

Thanks a lot to Cik Hayati Sidek becauses he had taught and shows me how to

complete this task correctly. It is a useful experience to know how to do this experiment.

Whatever it is this experiment had give me a lot of experiences and feeling although it

quite difficult. Thank you.


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NAME: NAWWAR BASIRAH BINTI MOHD SOLEHUDDIN

I learnt many new things when conducting this experiment. I learnt that to

achieve an accurate result in any experiment, I have to be careful in all my actions. For

example, in this experiment I have to add the chemicals into the KA1 and KA2 slowly so

that me and my partner can see the reaction occur inside the solution. This is because

the reaction or the change of colour of the solution will be hard to observe if the

chemicals is added in a hasty manner.

Besides that, I also have to make sure that all of the apparatus is clean, no other

substance or any impurities inside them because if this happen the result gained will not

be correct. The chemicals that are supposed to react with solids KA1 and KA2 will react

with the impurities inside the apparatus. So, all of the apparatus is cleaned with distilled

water.

Lastly, I also learnt that we should know and understand all the needs such as

the procedures and the apparatus so that the experiment can be conducted smoothly.

The experiment will turn into a chaos if we dont understand the procedure. So, to have

a very accurate result, we have to be careful and take all the precautions seriously.

report scince 2 (sem 2)

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