Variables:
Controlled: The PH values of the sodas
Manipulated Variable:
The amount of phenolphthalein indicator used
Responding Variable: Rate at which the soda turns purple
Treatment of Results:
Burette reading
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Trial
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Final volume
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Initial volume
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Volume used
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Sprite Average Volume of NaOH used: (_______+_______+________)/3 = ____47.15_____cm3
Burette reading
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Trial
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Initial volume
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Volume used
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Ting Average Volume of NaOH used: (_______+_______+________)/3 = ____47.15_____cm3
Precautions:
make sure the gruaduated beakers are rinsed thoroughly before using them.
Wear gloves for the protection from corrosive chemicals.
All You Need to Know!
Name: _________Abbyshay Gayle_______________
Lab Write-up Sheet
Date: ___/___/___ Lab No. 13
Module: 3 Ligand Exchange Skills tested: ORR, A&I
Aim: To demonstrate the process of ligand exchange.
Introduction
Transition metal ions in aqueous solution form complexes. However, depending on amount of a competing ligand and its stability constant, ligand exchange can occur with an accompanying colour change.
Procedure
3 cm3 of aqueous Co2+ ions was added to a test tube. Its colour was recorded.
HCL conc was added slowly to the test tube until no further changes occurred. All observations were recorded.
¾ of the mixture was decanted and then distilled water was added slowly until no further changes occurred.
Steps 1 to 3 was repeated aqueous Cu2+ ions
Steps 1 to 3 was repeated using aqueous Fe3+ , however instead conc added. A small amount of
ammonium thiocyanate was added to the test tube.
The table below was completed.
Inferences should include the formulae of the complex ions present and a brief explanation of colour changes.
Results
Test
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Observations
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Inferences
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1
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The colour of aqueous Co2+ was pink,small amount of co2 reacted with Hcl to make hydrogen ions.It turned a dark blue colour
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When chloride ion in the form of hydrochloric acid is added to the solution, the color changes to blue, corresponding to the formation of a charged coordination complex between Co2+ and chloride ions.
Formula Co(H2O)6 2+ + 4Cl– + heat ←→ CoCl4 2– + 6H2O
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2
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No change was noted
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There can be no molecular H2CO3 in water. It is impossible for aqueous solution doesn’t exist in aqueous solution.H20+CO2←→H2CO3
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3
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The colour of the aqueous Cu2+ was reversible and a mixture of both green and blue due to both complex ions.
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when a water is added to the green solution, it returns to the blue colour. ... In contact with water, though, it slowly turns blue as copper(II) ions are formed.
The formula is
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4
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The colour of Fe3+ is yellow solution when Hcl was added in HCl, it wasl oxidized gradually. small bubbles of hydrogen gas evolve. But not vigorous.
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Fe3+reacts fairly slowly with hydrochloric acid
Fe(s) + HCl (aq) → FeCl2 (aq) + H2 (g).
The reaction between iron and hydrochloric acid is slower than the reaction with zinc, with much smaller hydrogen bubbles produced.
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5
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When ammonium thiocyanate was added to Fe3+ it turned a blood red colour,
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.The reaction of of ammonium thiocyanate to Fe3+
NH4SCN+FeCl3→FeSCN2++NH4Cl+2Cl−
When in contact with Fe3+ ion solution in ferric alum solution the product of the reaction is a solution with a blood red colour, due to the formation of the thiocyanato iron complex Fe(SCN)3.
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