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Lab Report 8

Ionic Reactions in Aqueous Solutions

Name: Fadhlin Sakinah Binti Mohd Amzan Experiment Date: 25th March 2015

Partner’s Name: Hasif Azfar Bin Johari

Lab Section: 01

Results & Observation

NaBr Na2SO4 NaOH Na2CO3

NH4NO3 NR NR NR NR

Ba(NO3)2 NR

White

precipitate

formed

Solution turns

cloudy and

white

precipitate is

formed

White

precipitate

formed

AgNO3

Yellowish white

precipitate

formed

NR

Solution turns

light brown and

brown

precipitate is

formed

Pale light

brown

precipitate is

formed

1. Ba(NO3)2 and Na2SO4

Ba(NO3)2 + Na2SO4 BaSO4 + 2NaNO3

Ba2+ + SO42- BaSO4

2. Ba(NO3)2 and NaOH

Ba(NO3)2 +2NaOH Ba(OH)2 + 2NaNO3

Ba2+ + 2OH- Ba(OH)2

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3. Ba(NO3)2 and Na2CO3

Ba(NO3)2 + Na2CO3 BaCO3 + 2NaNO3

Ba2+ + CO32-BaCO3

4. AgNO3 and NaBr

AgNO3 + NaBrAgBr + NaNO3

Ag+ + Br - AgBr

5. AgNO3 and NaOH

AgNO3 + NaOHAgOH + NaNO3

Ag+ + OH -AgOH

6. AgNO3 and Na2CO3

2AgNO3 + Na2C Na2CO3O3Ag2CO3 + 2NaNO3

2Ag+ + CO32-Ag2CO3

Discussion

Precipitation reaction occurs when cations and anions in aqueous solution combine to

form an insoluble solid called a precipitate. Whether or not this reaction will occur can be

predicted by the solubility rules.

In the first four experiment where sodium bromide, sodium sulfate, sodium

hydroxide and sodium carbonate are reacted with ammonium nitrate, no precipitate is

formed. This is because, according to the solubility rules, salts containing Group 1

elements and salts containing ammonium ion are soluble, thus no precipitate is formed.

When barium nitrate is reacted with sodium bromide, no precipitate is formed

because according to the solubility rule, salts containing sodium ion (group 1 elements)

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and salts containing nitrate ion are soluble.

No precipitate is also formed when silver nitrate is mixed with sodium sulfate

because salts containing sulfate or nitrate ions are mostly soluble.

1. White precipitate is formed when sodium sulfate is mixed with barium

nitrate because although according to the solubility rules, salts containing sulfate ions

are soluble, there are exceptions for barium sulfate, lead sulfate, silver sulfate and

strontium sulfate. The white precipitate formed is barium sulfate.

2. White precipitate is formed when barium nitrate is mixed with sodium

hydroxide. The precipitate formed is barium hydroxide. The solution turns chalky

because hydroxide salts of group 2 elements such as barium are slightly soluble.

3. White precipitate which is barium carbonate is formed when barium nitrate

reacts with sodium carbonates. According to the solubility rules, carbonate salts are

generally insoluble thus a precipitate is formed.

4. According to the solubility rules, halide salts are soluble but there are

exception such halide salts of silver ions which are insoluble. So when silver nitrate

is mixed with sodium bromide, a yellowish precipitate is formed which is silver

bromide.

5. Brown precipitate is formed when silver nitrate is mixed with sodium

hydroxide. Although according to the solubility rules hydroxide salts are soluble,

silver hydroxide which is the brown precipitate is an exception as it is not soluble.

6. Light brown precipitate which is silver carbonate is formed when silver

nitrate and sodium carbonate is mixed. According to the solubility rules, most salts

containing silver ions are insoluble.

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The color of some of the precipitate might be a little inaccurate as there could be

some error during the mixing. This error might be caused by uncleaned test tubes that

probably contained other substance that could impact the ending results. Precautions

should be made to make sure that all test tubes are cleaned before mixing the solutions. A

vortex mixture should also be used to make sure the solution are mixed thoroughly.

Conclusion

Precipitation reaction occurs when ions in aqueous solution combine to form an

insoluble solid called a precipitate. Salts containing group 1 ions and ammonium ions are

always soluble. Nitrates salts are generally soluble. Halide salts are generally soluble

except halide salts containing silver, lead and mercury ions. Most silver salts are insoluble

except for silver nitrate. Most sulfate salts are soluble except sulfate salts containing

barium, lead, calcium, strontium, silver and mercury ions. Most hydroxide salts are

soluble except for hydroxide salts of transition elements and aluminium which are

insoluble. Sulfides of transition elements are also insoluble. Carbonates, phosphate,

chromates and fluorides salts are usually insoluble. The solubility rules can be used to

predict the formation of precipitate.

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