Reactivity Of Alkanes And Alkenes Aim: To compare the reactivity of Cyclohexane and Cyclohexene using bromine water Hypothesis: The cyclohexene will react due to the presence of its double bond. SAFETY: 1. Wear safety goggles and gloves at all times during the experiment, as the organic solvent can be absorbed by soft tissues. 2. Organic Liquids are volatile and flammable, Hence keep away from fire sources, Use very small quantities of chemicals [Can cause skin irritations and respiratory problems] 3. Toxic Fumes, Avoid breathing in bromine water, performed in a fume cupboard. 4. WASTE DISPOSAL: Dispose of chemical wastes in supplied waste containers, not sink. Method 1. Place two test tubes in a test tube rack and add 5 drops of bromine water to each teats tube, observe and record their initial colour in a table. 2. Add 8 drops of Cyclohexene to the first test tube then stopper it, start the stopwatch and then gently shake the test tube and place it back on the rack. 3. Stop the stopwatch at 2 min and observe and record the final colour of solution in a table 4. Repeat steps 2 and 3 using Cyclohexane in the second test tube 5. Dispose of waste chemicals in the waste containers supplied by the teacher. 6. Repeat the entire experiment 10 times. Justify the method: - Cyclohexene was used instead of ethylene or propene, as C1 to C4 are gases at room temp - Cyclohexene and Cyclohexane were used instead of hexane/ane as cyclic hydrocarbons are more stable than their linear counterparts, Less toxic etc Results Hydrocarbon Initial Colour Of Bromine Water Final Colour of solution Cyclohexene Reddish-brown Colourless Cyclohexane Reddish-brown Reddish-brown
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Reactivity Of Alkanes And Alkenes Aim: To compare the reactivity of Cyclohexane and Cyclohexene using bromine water
Hypothesis: The cyclohexene will react due to the presence of its double bond.
SAFETY:
1. Wear safety goggles and gloves at all times during the experiment, as the organic solvent
can be absorbed by soft tissues.
2. Organic Liquids are volatile and flammable, Hence keep away from fire sources, Use very
small quantities of chemicals [Can cause skin irritations and respiratory problems]
3. Toxic Fumes, Avoid breathing in bromine water, performed in a fume cupboard.
4. WASTE DISPOSAL: Dispose of chemical wastes in supplied waste containers, not sink.
Method
1. Place two test tubes in a test tube rack and add 5 drops of bromine water to each teats
tube, observe and record their initial colour in a table.
2. Add 8 drops of Cyclohexene to the first test tube then stopper it, start the stopwatch and
then gently shake the test tube and place it back on the rack.
3. Stop the stopwatch at 2 min and observe and record the final colour of solution in a table
4. Repeat steps 2 and 3 using Cyclohexane in the second test tube
5. Dispose of waste chemicals in the waste containers supplied by the teacher.
6. Repeat the entire experiment 10 times.
Justify the method:
- Cyclohexene was used instead of ethylene or propene, as C1 to C4 are gases at room temp
- Cyclohexene and Cyclohexane were used instead of hexane/ane as cyclic hydrocarbons are
more stable than their linear counterparts, Less toxic etc
Results
Hydrocarbon Initial Colour Of Bromine Water Final Colour of solution
Cyclohexene Reddish-brown Colourless
Cyclohexane Reddish-brown Reddish-brown
DISCUSSION:
- The experiment showed that bromine water changed colours from reddish-brown to
colourless when cyclohexene was added to it. [Since alkenes have a highly reactive double
bond (High electron density), Which easily reacted with the bromine water [Br2(aq)].
- However when cyclohexane was added to bromine water no decolourisation occurred
o Since alkanes more stable single bonds, Need addition energy to break the C-H bonds, If
UV light present, reaction will undergo slow substitution reactions.
ACCURACY: A control was used (the test tubes with no bromine water)
- Accuracy affected by; The age of bromine water (Made colour changes less visible) Need
fresh Br2(aq), Dropper was aimed at centre of test tube, Same person used stopwatch for test
o Accuracy was affected by small quantities of soln| Same size of test-tubes were used
VALIDITY:
- Fairly valid, Only one variable was changed, All other Variables were controlled, Include ↓
o CONTROLLED: The number of drops of Cyclohexane/ene and bromine water used, All
reactions were stoppered after the reactants and was gently shaken for the same time.
o INDEPENDENT: The type of hydrocarbon whether it was an alkene or alkane.
o DEPENDENT: The rate of decolorisation of the bromine water from brown to clear.
- Validity was affected by the Amount of UV light in the room (Provided addition energy for
other reaction) Not near window, Minimised by covering in aluminium foil.
- Overall the experiment is valid as all necessary variables were controlled.
RELIABILITY:
- The experimental results are reliable because it was repeated several times and consistent
results were achieved, It also accounted for theoretically expected results, Hence reliable
IMPROVEMENTS:
- Using larger quantities of the solution, Freshly made bromine water
- Using a measuring cylinder to measure volumes of reactants
CONCLUSION:
Cyclohexene decolourises in bromine water hence is more reactive than cyclohexane which
does not decolourises in bromine water| Indicates alkenes more reactive than matching alkane
Fermentation Practical AIM: To carry out the fermentation of glucose and monitor mass changes.
EQUIPMENT:
o Electronic balance o 250ml Conical flask o Rubber stopper with hose
o 150ml beaker
o 20g of glucose (Sugar) o 7g of dried yeast o l00ml of water o 75ml limewater [Ca(OH)aq]
SAFETY: Wear safety glasses and gloves to avoid the spashing of chemical, I.e Prevent limewater from coming into contact with eyes since limewater is very basic (Ca(OH)2).
METHOD:
1. Measure 250 ml of water, 25 g of glucose, 7 g of yeast respectively using an electronic
balance, and add them into the conical flask and swirl to mix.
2. Measure and record the initial mass of the conical flask and its contents
3. Half fill a 150ml beaker with limewater and measure and record its mass using balance
4. Stopper the conical flask and completely immerse the end of the tube into the limewater
5. Put the two containers in a warm area and record the appearance mixture and limewater
6. Repeat the weighing and observations of each container daily for 2 more days.
7. Repeat the entire experiment 5 times.
Results
* Include a table column with change in mass
Discussion
- The experiment showed that the mass of the fermentation mixture decreased from x to
y, as CO2 Gas produced by fermentation
dissolved in the lime water, producing a
milky white precipitate, with the corresponding increase in the mass of limewater
ACCURACY:
- Fairly accurate, Electronic balance measured to ± 0.1g accuracy
- Environment was subject to changes in temperature
- Leaks were minimised by taping the conical flask to the rubber stopper.
VALIDITY:
- The experiment is valid as it investigates the aim. Also Only one variable was changed
(Independent), While the other Variables were controlled
o Independent: Number of days | Dependent: Mass Change
o Control: Location in room, Temperature of environment
- Validity affected as some of CO2 escaped from mixture, Different then theorectical.
RELIABILITY:
- The experimental results are reliable because were compared with the class and
consistent results were achieved
Conclusion
- The fermentation of glucose decreased the mass of the mixture by 5.9g and the
limewater turned milky, indicating the presence of C02.
Heat Of Combustion Practical AIM: To determine and compare the heats of combustion of ethanol, 1-butanol and l-
propanol per gram and per mole.
EQUIPMENT:
ethanol spirit burner
l-butanol spirit burner
I -propanol spirit burner
200m1 water
250m1 beaker
Stirring rod
Thermometer
Tripod
Gauze mat
Heat proof mat
SAFETY:
- Be careful with these highly flammable chemical and wipe any spills before lighting a match.
- Wear your safety goggles to prevent chemicals or hot water touching your eyes.
- Tie back long hair so it cannot catch fire
- Do not inhale poisonous l-propanol or l-butanol vapours.
Method
1. Pour 200ml of water into a beaker, then measure its mass using an electronic balance
2. Measure the mass of each spirit burner using an electronic balance and record mass
3. Set up apparatus as shown in the diagram. 4. Measure the temperature of the water using a thermometer and record it in a table 5. Light the ethanol spirit burner and stir the water while it is being heated. 6. Measure and record the temperature of the water after it has increased by l0oC. 7. Put out the spirit burner flame and let it cool before measuring its mass and recording it
in a table. Repeat steps 4 to 7 for each l-propanol and 1-butanol. 8. Calculate the heats of combustion for each liquid alkanol per gram and per mole.
Mass 200ml water = 189.6 |Also include amount of fuel burn (g)| Need molar mass for calculations
Calculations
DISCUSSION:
- The experiment showed that Butanol had the highest heat of combustion with X kJ/Mol,
Followed By Propanol with Y kJ/Mol, and finally ethanol with z kJ/Mol
o Larger Alkanols have extra CH2 group to chain, and thus extra H2O and CO2 are
produced, more bonds formed, > Energy released. Higher heat of combustion
- Accuracy: Very inaccurate, showed a X % error for the combustion with the theoretical
value. The calculated figure differ from the actual figure because:
o Heat lost to atmosphere, absorbed by tripod, gauze mat and beaker|Use Wind shield
o The thermometer touching the beaker instead of measuring the temp of the water.
o There may have been some incomplete combustion of the ethanol.
o The soot (carbon) that deposited on the beaker may have absorbed some of the heat.
The accuracy of the experimental method or apparatus could be improved by:
- Using a temperature probe and data logger
- Using a balance that measured to more decimal places
Validity
- validity is compromised due to large amount of heat lost to the surroundings
- The experiment method is partly valid as it is able to compare the Heat of combustion
between Alkanols, However did not accurately calculate heat of combustion
o Variable controlled- Independent: Type of Alkanols | Dependent: Heat of Combustion
The validity of the experimental method or apparatus could be improved by:
o Attaching the thermometer in the centre of the beaker, also removing the tripod and
gauze mat and holding the beaker up with a retort stand and clamp
o Moving the ethanol burner closer to the beaker of water, Using an insulated calorimeter
o Ensuring complete combustion of the ethanol by supplying sufficient oxygen
o Removing soot (carbon) from the bottom of beaker, Increase purity of Alkanols used
CONCLUSION: The heat of combustion of the Alkanols increased with molecular weight, It
was found that butanol had highest heat of combustion followed by Propanol and ethanol
Galvanic Cell Practical AIM: To investigate and measure the differences in voltage when different combinations of
metals are used in constructing a galvanic cell.
EQUIPEMENT:
o 3x l00mlbeakers
o 1 x2 ml beaker
o 1 x voltmeter
o 1 mol/L zinc nitrate, copper nitrate,
magnesium sulfate
o 3 x strips of filter paper (l cm by l0 cm)
o 3 x strips of filter paper (l cm by l0 cm)
o Strips of zinc, copper and magnesium
o Saturated potassium nitrate solution
o 2x connecting wires
o 2x alligator clips
o Steel wool
SAFETY:
- Lead nitrate is toxic, so hands must be washed after use, spills cleaned up immediately
- Wear safety goggles to prevent chemicals from coming into contact with eyes
- Dispose of waste solutions in a supplied waste container, do not pour down the sink.
METHOD: 1. Clean all the metal strips with steel wool.
2. Place 50ml of zinc nitrate, copper nitrate and magnesium sulfate soln into 3 separate beakers
3. Soak filter papers in saturated potassium nitrate solution and leave to soak.
4. Add the zinc to the zinc nitrate solution and the copper to the copper nitrate solution.
5. Take out a piece of filter paper and connect the zinc beaker to the copper beaker with the filter
paper dipping into each solution.
6. Connect the zinc and copper to a voltmeter using the wires and alligator clips.
7. Note which electrode is positive and record the magnitude of the voltage
8. Remove the salt bridge and note what happens.
9. Repeat steps 4 to 7 using the following metal combinations
Cell Beaker A Beaker B
1 Zn + 1M Zn (NO3) 2 Cu + 1M Cu (NO3) 2
2 Zn + 1M Zn (NO3) 2 Pb + 1M Pb (NO3) 2
3 Zn + 1M Zn (NO3) 2 Fe + 1M Fe (NO3) 2
4 Pb + 1M Pb (NO3) 2 Fe + 1M Fe (NO3) 2
5 Cu + 1M Cu (NO3) 2 Fe + 1M Fe (NO3) 2
6 Pb + 1M Pb (NO3) 2 Cu + 1M Cu (NO3) 2
Results
Discussion
- The experiment showed the voltage produced by metal combination, Also showed the
need of the salt bridge to complete the circuit (Balance the charges in each half-cell).
Reliability:
The experimental results are reliable because it was repeated several times and consistent
results were achieved, It also accounted for theoretically expected results, Hence reliable
Validity
- Valid, Only one variable was changed, All other Variables were controlled, Include ↓
o Controlled: Volume of solution used, type of salt bridge used and the voltmeter used.
o Independent: Metal Combinations | Dependent: Output voltage
Accuracy
- Not accurate as the value we obtained were significantly lower than theoretical results
o Since electrodes, alligator clips and wires were corroded ( Leads to > resistance,
reduced voltage), Analog Voltmeter Difficult to make measurements ± 0.1 V error
o Presence of impurities in solution, low quality voltmeters (High resistance)
o The salt bridge may have dried up, hindering the movement of ions reduce voltage
JUSTIFICATION
- We cleaned the electrode with steel wool before use to remove impurities
- We used a potassium nitrate salt bridge, which does not form precipitates with any of
the electrolytes used so does not affect the half-cell reactions help balance charges
Conclusion
- Each metal combination produced a voltage in their respective electrolyte solution
MODELING RECATIONS (using ball and stick models)
ADVANTAGES
- Allows us to represent bond breakage and bond formations that occur during reactions
- Provides a 3D representation of a reaction, which leads to a better understanding when
compared to liner equations |Shows the shapes of reactants and products
- Shows the spatial arrangement of atoms
DISADVANTAGES
- Ball and stick models cannot perfectly re-create the shape of reactants and products as
there are only certain places for sticks to attach to balls
- Hard to explain the strength of the bond.
THE ACIDIC ENVIROMENT- Indicator Prac
Aim: To prepare and test a natural indicator
Equipment:
Beetroot
Cutting Board +Knife
250mL beaker
l00ml water + Bunsen Burner
Dropper Bottle
5 x test tube
Test tube rack
Distilled Water
2mL of 1M Of NaOH
2mL of 2M Of NaOH
2ml of 1M HCI
2mL of 2M HCl
RISK ASSESMENT
- If acid/basic solution come into contact with skin and eyes, they may cause irritation and
burns, to avoid safety glasses and gloves must be worn at all times.
- During heating, the beaker may become hot, allow it to cool before handling it.
Method
1. Use a cutting board and knife to finely cut beetroot and place it in a beaker
2. Add 100 ml of water, and boil using the Bunsen burner for 5 min, and leave to cool
o Strain the beetroot solution to remove remaining beetroot
3. Add 5 drops of distilled water, 1M NaOH, 2M NaOH, 1M HCI and 2M HCI into 5 separate
clean test-tubes using dropper bottles
4. Using a dropper bottle draw up some of the beetroot solution (the natural indicator) and
add 5 drops to each test tube and record the change in colour of the indicator.
Results
In distilled water, it was DARK PURPLE.
In the NaCl solution, it was DARK RED.
In the HCl solution, it was PINK.
In the NaOH solution, it turned YELLOW
Discussion
- The experiment showed that the original purple colour changed to pink on addition of
HCL (Acidic Conditions) and yellow in NaOH (Basic Conditions)
Reliability: The experiment was reliable because it was repeated in exactly the same way by other groups in the class and we achieved similar results.
Accuracy: Results were qualitative and a beaker was used for measurement of the water
which was accurate enough to determine colour change. However a pH meter could be used
Validity
- The experiment is valid, Only one variable was changed, Other Variables were controlled,
o Control: volume of solution used, conc of solutions used, amount of indicator added.
o Independent: Acidic/basic nature of chemical |Dependent: Colour change indicator
JUSTIFICATION
- We also tested indicator with substances with a variety of pH to accurately determine
the colours, allowing us to test the colour of the indicator over large range of pH values.
- Beetroot was used as it readily available and gives off easily identifiable pigment
- Canned beetroot was not used as it often contains preservatives
LIMITATIONS: We were not able to determine the exact pH at which beetroot changes color
and the transition range of the indicator; this could have been done using a pH probe.
Conclusion:
Beetroot is a natural indicator that changes colour when mixed with an acid or base.
pH Probe Experiment Aim: To use pH probes and indicators to distinguish acidic, basic and neutral chemicals.
Aim 2: And To measure the pH of identical concentrations of strong and weak acids
Safety
- Wear safety glasses throughout this experiment.
- Dilute ammonia solution is mildly toxic. Its fumes should not be inhaled.
- Do not allow bleach to contact the skin, eyes or clothes.
- Identify other safety precautions relevant to this experiment by reading the method
- Independent: Amount of Na2CO3 used|Dependent: Concentration of acid
RELIABILITY:
- The experimental is reliable because it was compared with other member of the class
and consistent results were achieved, It also accounted for theoretically expected results
Conclusion: A standard solution of sodium carbonate was successfully prepared and titrated
against HCl to find its concentration as 0.102 mol/L.
Titrating A Household Substance AIM: To find the concentration of acetic acid in household vinegar using tech (Data Logger)
EQUIPMENT:
Household vinegar
Distilled water
Burette and clamp
Glass funnel
Pipette and filler
Volumetric flask
Conical flask
Retort stand
White card
Data Logger + Comp
Phenolphthalein indicator
Standardized 1M NaOH
Method 1. Rinse pipette and burette with water and then 5mL of vinegar and NaOH respectively 2. Use a pipette to add 25mL sample of the vinegar into a 250mL volumetric flask. 3. Add distilled water to the fill the flask to the 250mL mark. 4. Use pipette to extract 25mL aliquot (sample) of diluted vinegar add this to conical flask. 5. Fill your burette with a 0.1M solution of NaOH. 6. Clamp the burette to a retort stand and position the volumetric flask under it. 7. Connect the pH probe to the computer and then remove the cap from the pH probe. 8. Place your pH probe into the vinegar flask, holding it upright through the experiment. 9. Open burette tap to let NaOH run into the flask I mL at a time until pH reaches
o Note reaction is between strong acid and strong basic so produce neutral salt.
10. Obtain a titration graph using your computer
Validity
- Overall experiment is valid, Only one variable was changed, Other Variables controlled
- Control: Size of pipettes/Burettes/Comical flask, Vol Solution used,
- Independent: Amount of NaOH used|Dependent: Concentration of acetic acid
Accuracy
- A pH probe/Data logger used and the computer recorded the results. This significantly
increased accuracy pH correct to 2dp gives a quantitative results unlike an indicator
- All equipment was used correctly and washed with correct techniques
- Experimental errors while reading the values on the pipette and burette, could be
minimized by reducing parallax error and using a magnifying glass
- The vinegar was diluted in order to ensure an accurate volume was used
- Improvement: We could have had a rough run to approximate when to slow the rate of
NaOH into flask and could have used indicator to confirm (validate) equivalence point
Conclusion
The concentration of acetic acid was found to be X and had an equivalence point of Y
PREPARING AN ESTER AIM: To prepare an ester using reflux 1-pentyl ethanoate (banana flavor)
EQUIPMENT:
Condenser
Round bottom flask
Heating mantle
Retort stand
Boiling chips
Conc sulfuric acid
1-pentanol
Ethanoic acid
Separating funnel
Distilled water
Sodium carbonate solution
RISK ASSESMENT
- Vapors produced by reaction are highly flammable so should be kept away from flame
- Substances used in experiment are highly corrosive so safety glasses/gloves worn
- Sulfuric acid is corrosive. Clean up spills immediately
METHOD
1. Place 10mL of 1-pentanol, 10mL of ethanoic acid, 1mL of sulfuric acid and a few boiling
chips into a round bottom flask., And place inside a heating mantle
2. Fix a water condenser upright into the flask using a retort stand
3. Turn on the water supply to condenser , And heat mixture under reflux for 30 min
4. Carefully pour the mixture into the separating funnel and add 10mL of water to it.
5. Stopper and shake funnel, allow layers to separated and discard the lower aqueous layer
6. Add 15mL of sodium carbonate solution, shake and discard the lower layer,
7. The layer remaining in the flask is the ester, which is further purified by distillation
Results: Initially ester smelt of nail polish before it was distilled, after it smelt like banana
DISCUSSION
- The ester was first washed with water to dissolve any remaining reagents and remove
this from the mixture, Since esters are insoluble (form an organic layer over the top. )
- The sodium carbonate was added in order to neutralize any remaining sulfuric acid
JUSTIFICATIONS
- Conc sulphuric acid used acts as a catalyst speeds up reaction, Dehydrating agent
- Boiling chips to promote even heating and prevent bumping
- Reflux was used to prevent the escape of any volatile vapors, allowing us to perform the
reaction at higher temperatures, boost the reaction rate and shift ↔ to favour ester yield
- We used an indirect heating source (not a Bunsen burner) to promote even heating and
prevent any vapours (Volatile Substance) produced igniting. Also increase safety
Conclusion: We were able to prepare the ester 1-pentyl ethanoate (banana flavor)
Deduce the ions present in a sample from the results of tests.
Aim: Measure the sulfate content of lawn fertiliser and explain the chemistry involve
EQUIPMENT
- 5g fertilizer
- Electronic balance
- Stirring rod
- 500ml beaker
- Sintered glass funnel
- 50 ml hydrochloric acid
- Bunsen burner
- Distilled water
- Mortar and pestle
- Barium chloride solution
RISK ASSESMENT
- HCl is highly corrosive and can burn the skin and eyes on contact, thus gloves and safety
glasses should be worn.
METHOD
1. Grind the fertiliser using a mortar and pestle into to a fine powder
2. Weight out 5g of fertilizer using an electronic balance, and carefully transfer all of it into a
500ml beaker, with the help of a wash bottle.
3. Add 100 mL of water and 50mL hydrochloric acid to the beaker and stir until all fertilizer
dissolves
4. Barium chloride was slowly added till no more precipitate formed
5. Heat the mixture below its boiling point (digesting) for 30mins and stir every now and then.
6. The sintered glass filter was weighed, and then the mixture was filtered through it.
7. The filter was then washed with distilled water and ethanol to remove any impurities
8. The filter was then dried in an oven until its mass became constant
9. The filter was re-weighed and the mass of barium Sulphates recorded
10. Calculate the mass of Sulfate and the % of Sulfate in the original sample of lawn fertiliser
Problem encountered Solution
Not all the fertilizer dissolved (if
this occurred not all sulfate would
dissolve leading to inaccurate
results) (some sulfate compounds
are insoluble)
We finely ground up the fertilizer to aid in dissolving
HCl to further aid dissolution
Some precipitate was lost during
filtration (the solubility of barium
sulfate is low so some may passes
through the filter un-dissolved)
We used a sintered glass filter as opposed to filter paper
as the larger pore size of filter paper would allow more
precipitate through
We allow the mixture to digest for 30mins which helped
to clump the precipitate together and made it easier to
filter
The mixture was cooled in ice water to reduce the
solubility of barium sulfate and cause it to precipitate out
Slowly forming precipitates using a dropper bottle in
high temperatures promoted the growth of larger
clumps of precipitate
Incomplete drying of the glass filter The filter was dried in an oven
Could be improved by placing in a desiccator
Fertilizer remained in mortar,
precipitate still stuck to beaker
The equipment was washed into the next stage to
remove any traces of remaining particles.
Heterogeneous composition of the
fertilizer
The experiment is repeated 5 times and outliers
excluded from averages.
Aim: Perform a first-hand investigation to model an equilibrium reaction
EQUIPMENT
- 2 x 100mL measuring cylinder
- 10mL pipette
- 2mL pipette
- Water
METHOD
1. One 100mL measuring cylinder (cylinder 1) was filled with 100mL water while the other
one was left empty (cylinder 2)
2. A 10ml pipette was placed into cylinder 1, and the water was allowed to rise, this volume
was then transferred to cylinder 2 [Represents Forward Reaction: Water A Water B]
3. The 2mL pipette was then placed in cylinder 2, and the water was allowed to rise, this
volume was then transferred to cylinder 1 [Backwards reaction: Water B Water A]
4. The volume of both cylinders was recorded
5. Steps 2 and 3 are repeated for 20 times
DISCUSSION
- Cylinder 1 represents the concentration of reactants, and the volume transferred from it
refers to the forward reaction
- Cylinder 2 represents the concentration of products, and the volume transferred form it
refers to the reverse reaction
- When the depth of water is high in a cylinder (i.e. the concentration is high) the volume
transfers increases, which is consistent with Le-Chatelier’s principle which suggest hat if
the concentration of a species is high, the equilibrium shifts towards the other side of the
equilibrium
- When the volumes becomes constant, the rate of forward reaction has reached the rate
of reverse reaction and our system is in equilibrium
- Equilibrium could be disturbed by adding extra water into Measuring cylinder A
Aim: To qualitatively analyses an equilibrium reaction.
- Iron(III) ions react with colourless thiocyanate ions, SCN–
, to form an intensely red-
coloured complex in an equilibrium reaction: Fe3+
(aq) + SCN– (aq) Fe(SCN)
2+(aq)
Method
- Using a clean pipette for each, transfer 5ml of 0.1 mol/L iron (III) nitrate Fe(NO3)3 & 5 ml
of 0.1 mol/L potassium thiocyanate KSCN solution respectfully, into clean 250 mL beaker.
- Add 100 mL of distilled water and mix the chemicals thoroughly
- Add 10 mL of this mixture was added to each of the 4 medium size test tubes.
- Tube 1 was a control; It enabling colour (And intensity) changes to be compared to.
- The other test tubes were treated as follows
o Tube 2: Added 10–15 drops of Fe(NO3)3 solution
o Tube 3: Added 10–15 drops of KSCN solution.
o Tube 4: Added a few drops of 2 mol/L NaOH solution.
o Tube 5: Add 1.0 g solid potassium nitrate.
o Tube 6: Heated in a water bath.
o Tube 7: Placed in an ice cold water bath.
- Colour changes and colour intensity changes were observed with reference to the
control, and results were recorded in a table.
Results: Explain how you analysed the equilibrium reaction qualitatively.
- Addition of NaOH (aq) results in the OH- reacting with the Fe3+ ions forming a ppt of
Fe(OH)3. Conc Fe3+ decreases by LCP backward reaction favoured, Lighter red colour
- Adding KSCN solution results in the conc of SCN- to increase, According to LCP the
forward reaction rate is favoured, Red Darker red colour.
- Heating the mixture resulted in the backwards endothermic reaction to be favoured by
LCP, Blood Red Lighter Red (decrease to the colour intensity)
- Cooling the mixture resulted in the forward exothermic reaction to be favoured by LCP to
remove heat, Blood Red Darker Blood red (decrease to the colour intensity)
Light Yellow Colourless Blood Red
Aim: To identify the products of the electrolysis of sodium chloride
RESULTS/Discussion:
- In the dilute solution we observed bubbles forming at the 2 electrodes indicating gasses