Titration, calibration, and colourimetry
Assignment 1 Sadia Noor
Introduction
It is important to calibrate equipment before using it because it helps the results to be more
accurate as the equipment is rested. Equipment over time becomes less accurate and their
use begins to slowly decrease, making calibration a crucial step. Calibration can also
minimise the changes in the equipment causing any issues when being used in experiments.
Calibrating an electrical balance
The calibration of an electrical balance is important as equipment which is not calibrated will
over time begin to become less accurate, and it will need repairing once this happens too.
During experiments, if the electrical balance is providing inaccurate results, this will impact
on the whole experiment and will make the whole experiment result in inaccurate results.
When calibrating an electrical balance, it is important to place the balance onto a surface
which is flat. This is because if the balance is placed on an uneven surface, then the readings
may come out inaccurate which can cause an error in the whole experiment itself. Once the
balance is put onto a flat surface, switch it on and then press the button which says “CAL” on
it once 0.00g appears on the display of the electrical balance.
Calibration of pH probe using buffer solutions
The use of a pH probe is important as it allows unknown solutions to be determined about
how acid or alkaline a solution is. As stated before, the calibration of equipment is very
important before using it to get an accurate result. In this case, we would need an accurate
result to determine the pH of a substance which could be unknown. The calibration of a pH
probe would first be to twist off the plastic cap on the pH probe gently without causing any
damage to it. The glass part is then required to be rinsed with distilled water which is done
using a beaker for the water to fall into when washing. This is done to make the results
precise, especially if any solution was left on the pH probe from the last time it had been
used. The pH probe should then be dried using some clean tissue paper because if this step
is missed it could lead to an inaccurate result to be made of the solution’s pH. The probe
should also not be left dry for long as this can damage the probe and impact the readings
given. The solution which is going to be tested will then need to be put into a beaker which
the pH probe will then be lowered into gently. In this calibration, I put the pH probe into the
buffer solution of pH 4 and 7 When the pH probe is in the beaker, it must not touch the glass
as this can cause the glass to break especially as it is very fragile. Gently the pH buffer in the
beaker should then be swivelled around without the pH probe touching any glass. Then
press the button which says Cal to get the results of which pH the solution is. When this has
been done it is important for the pH probe to be taken out gently and then distilled water is
needed to rinse the probe before putting its cap back on.
Calibration of volumetric pipette
The volumetric pipette needs to be filled up to the calibration mark of the volumetric
pipette. This is going to be done by using the pipette filler by inserting it at the top of the
volumetric pipette and rolling the dial on the side of the pipette filler. This will allow the
water to be suctioned into the volumetric pipette. When this is done there should also be no
1
,Titration, calibration, and colourimetry
Assignment 1 Sadia Noor
air bubbles. Remove the volumetric pipette from the beaker that it was extracting the water
from and then clean the outside of the volumetric pipette by wiping it dry to prevent
inaccuracy. The tip of the volumetric pipette should not be touching the bottom of the
beaker as it could break like this, and it could potentially also cause air bubbles to come into
the pipette. Once the pipette filler has allowed the pipette to suction the water up to the
calibration line, the pipette filler should be removed and immediately after this, the thumb
should cover the volumetric pipette to prevent any of the water from escaping. The level of
meniscus needs to then be at the calibration mark which means some of the water in the
volumetric pipette will need to be let out. Then the water will need to be let out fully from
the volumetric pipette into a beaker. When this is being done, the volumetric pipette needs
to be touching the side of the beaker to ensure all the liquid is let out of the volumetric
pipette and is not left within it. There will also be a small amount of water inside the tip of
the volumetric pipette which should not be blown out as the volumetric pipette may be
contaminated with some chemicals which should not be entered within the body.
Calibration of burette
When calibrating a burette, it is important that the tap of the burette is closed. Once there is
water within the burette, gently move the burette around and pour it out from the top of
the burette. Then put water back into the burette, place a beaker underneath to prevent any
spillages or do this step over the sink and then open the tap of the burette and release all
the water from there. Water then can be entered in the burette about 2 more times and all
the above steps can be repeated again as this will help to ensure it is calibrated for sure.
Titration background information
“A titration is a technique where a solution of known concentration is used to determine the
concentration of an unknown solution. Typically, the titrant (the know solution) is added
from a burette to a known quantity of the analyte (the unknown solution) until the reaction
is complete. Knowing the volume of titrant added allows the determination of the
concentration of the unknown. Often, an indicator is used to usually signal the end of the
reaction, the endpoint.”
https://chemed.chem.purdue.edu/genchem/lab/techniques/titration/what.html
Once the titration has occurred and the results have been found, the next step will be to
calculate the number of mols of the solution.
Hypothesis
The hypothesis for titration would be to find out how equilibrium is reached by having a
known solution which will be the titrant.
The null hypothesis is that titration does not state how much of the titrant is needed to
reach equilibrium.
Equipment needed for titration.
2
, Titration, calibration, and colourimetry
Assignment 1 Sadia Noor
A retort stand - has the double burette clamp attached to it to hold the burette and a
volumetric pipette.
A conical flask - will be needed for the titration to take place.
A pipette filler - will be needed for the volumetric pipette as this is going to help get
the right volume of the solution.
A funnel – carefully transfers liquids without spillage.
Distilled water - equipment will need to be washed using this to ensure there is no
cross-contamination with any other substances used.
An indicator (phenolphthalein) - is needed as this will help to show when the solution
has become neutralized.
Sodium Hydroxide
Hydrochloric Acid
Lab coats and goggles – safety equipment
Method of titration
1. Gather all the equipment needed for titration mentioned above.
2. Ensure lab coats and goggles are also worn to minimise the risk of any hazards.
3. Attach the double burette clamp to the retort stand.
4. Calibrate the volumetric pipette and burette as it is mentioned above previously. This
should be done using distilled water and should be repeated 3 times.
5. Rinse the volumetric pipette with hydrochloric acid (HCl).
6. Now the hydrochloric acid will need to go into the volumetric pipette using a pipette
filler until the hydrochloric acid reaches the calibration line marked on the top of the
volumetric pipette. In this step, it is important for the mark to be at the meniscus
base.
7. Transfer the hydrochloric acid from the volumetric pipette into a clean conical flask.
When this step is being done, it is important for the thumb to cover the top of the
volumetric pipette to prevent any of the liquid from escaping until it is inserted into
the conical flask.
8. The indicator phenolphthalein will need to be added into the conical flask too as this
will show us when the end point of the titration occurs as it will change the colour of
the liquid. Only 2-3 drops of this need to be added.
9. Rinse the burette with sodium hydroxide (NaOH).
10. Insert a funnel into the top of the burette and fill the burette using a beaker which
contains sodium hydroxide until it reaches point 0 of the burette. A beaker needs to
be placed under the burette during this step as there may be air bubbles which may
need to be released. In the case of an air bubble, the liquid should be left out in the
beaker until it has been removed. Also, the tap of the burette needs to be closed in
this step.
11. Remove the beaker from under the burette and replace it with the conical flask
which contains the hydrochloric acid and phenolphthalein as titration is ready to be
started.
3
Assignment 1 Sadia Noor
Introduction
It is important to calibrate equipment before using it because it helps the results to be more
accurate as the equipment is rested. Equipment over time becomes less accurate and their
use begins to slowly decrease, making calibration a crucial step. Calibration can also
minimise the changes in the equipment causing any issues when being used in experiments.
Calibrating an electrical balance
The calibration of an electrical balance is important as equipment which is not calibrated will
over time begin to become less accurate, and it will need repairing once this happens too.
During experiments, if the electrical balance is providing inaccurate results, this will impact
on the whole experiment and will make the whole experiment result in inaccurate results.
When calibrating an electrical balance, it is important to place the balance onto a surface
which is flat. This is because if the balance is placed on an uneven surface, then the readings
may come out inaccurate which can cause an error in the whole experiment itself. Once the
balance is put onto a flat surface, switch it on and then press the button which says “CAL” on
it once 0.00g appears on the display of the electrical balance.
Calibration of pH probe using buffer solutions
The use of a pH probe is important as it allows unknown solutions to be determined about
how acid or alkaline a solution is. As stated before, the calibration of equipment is very
important before using it to get an accurate result. In this case, we would need an accurate
result to determine the pH of a substance which could be unknown. The calibration of a pH
probe would first be to twist off the plastic cap on the pH probe gently without causing any
damage to it. The glass part is then required to be rinsed with distilled water which is done
using a beaker for the water to fall into when washing. This is done to make the results
precise, especially if any solution was left on the pH probe from the last time it had been
used. The pH probe should then be dried using some clean tissue paper because if this step
is missed it could lead to an inaccurate result to be made of the solution’s pH. The probe
should also not be left dry for long as this can damage the probe and impact the readings
given. The solution which is going to be tested will then need to be put into a beaker which
the pH probe will then be lowered into gently. In this calibration, I put the pH probe into the
buffer solution of pH 4 and 7 When the pH probe is in the beaker, it must not touch the glass
as this can cause the glass to break especially as it is very fragile. Gently the pH buffer in the
beaker should then be swivelled around without the pH probe touching any glass. Then
press the button which says Cal to get the results of which pH the solution is. When this has
been done it is important for the pH probe to be taken out gently and then distilled water is
needed to rinse the probe before putting its cap back on.
Calibration of volumetric pipette
The volumetric pipette needs to be filled up to the calibration mark of the volumetric
pipette. This is going to be done by using the pipette filler by inserting it at the top of the
volumetric pipette and rolling the dial on the side of the pipette filler. This will allow the
water to be suctioned into the volumetric pipette. When this is done there should also be no
1
,Titration, calibration, and colourimetry
Assignment 1 Sadia Noor
air bubbles. Remove the volumetric pipette from the beaker that it was extracting the water
from and then clean the outside of the volumetric pipette by wiping it dry to prevent
inaccuracy. The tip of the volumetric pipette should not be touching the bottom of the
beaker as it could break like this, and it could potentially also cause air bubbles to come into
the pipette. Once the pipette filler has allowed the pipette to suction the water up to the
calibration line, the pipette filler should be removed and immediately after this, the thumb
should cover the volumetric pipette to prevent any of the water from escaping. The level of
meniscus needs to then be at the calibration mark which means some of the water in the
volumetric pipette will need to be let out. Then the water will need to be let out fully from
the volumetric pipette into a beaker. When this is being done, the volumetric pipette needs
to be touching the side of the beaker to ensure all the liquid is let out of the volumetric
pipette and is not left within it. There will also be a small amount of water inside the tip of
the volumetric pipette which should not be blown out as the volumetric pipette may be
contaminated with some chemicals which should not be entered within the body.
Calibration of burette
When calibrating a burette, it is important that the tap of the burette is closed. Once there is
water within the burette, gently move the burette around and pour it out from the top of
the burette. Then put water back into the burette, place a beaker underneath to prevent any
spillages or do this step over the sink and then open the tap of the burette and release all
the water from there. Water then can be entered in the burette about 2 more times and all
the above steps can be repeated again as this will help to ensure it is calibrated for sure.
Titration background information
“A titration is a technique where a solution of known concentration is used to determine the
concentration of an unknown solution. Typically, the titrant (the know solution) is added
from a burette to a known quantity of the analyte (the unknown solution) until the reaction
is complete. Knowing the volume of titrant added allows the determination of the
concentration of the unknown. Often, an indicator is used to usually signal the end of the
reaction, the endpoint.”
https://chemed.chem.purdue.edu/genchem/lab/techniques/titration/what.html
Once the titration has occurred and the results have been found, the next step will be to
calculate the number of mols of the solution.
Hypothesis
The hypothesis for titration would be to find out how equilibrium is reached by having a
known solution which will be the titrant.
The null hypothesis is that titration does not state how much of the titrant is needed to
reach equilibrium.
Equipment needed for titration.
2
, Titration, calibration, and colourimetry
Assignment 1 Sadia Noor
A retort stand - has the double burette clamp attached to it to hold the burette and a
volumetric pipette.
A conical flask - will be needed for the titration to take place.
A pipette filler - will be needed for the volumetric pipette as this is going to help get
the right volume of the solution.
A funnel – carefully transfers liquids without spillage.
Distilled water - equipment will need to be washed using this to ensure there is no
cross-contamination with any other substances used.
An indicator (phenolphthalein) - is needed as this will help to show when the solution
has become neutralized.
Sodium Hydroxide
Hydrochloric Acid
Lab coats and goggles – safety equipment
Method of titration
1. Gather all the equipment needed for titration mentioned above.
2. Ensure lab coats and goggles are also worn to minimise the risk of any hazards.
3. Attach the double burette clamp to the retort stand.
4. Calibrate the volumetric pipette and burette as it is mentioned above previously. This
should be done using distilled water and should be repeated 3 times.
5. Rinse the volumetric pipette with hydrochloric acid (HCl).
6. Now the hydrochloric acid will need to go into the volumetric pipette using a pipette
filler until the hydrochloric acid reaches the calibration line marked on the top of the
volumetric pipette. In this step, it is important for the mark to be at the meniscus
base.
7. Transfer the hydrochloric acid from the volumetric pipette into a clean conical flask.
When this step is being done, it is important for the thumb to cover the top of the
volumetric pipette to prevent any of the liquid from escaping until it is inserted into
the conical flask.
8. The indicator phenolphthalein will need to be added into the conical flask too as this
will show us when the end point of the titration occurs as it will change the colour of
the liquid. Only 2-3 drops of this need to be added.
9. Rinse the burette with sodium hydroxide (NaOH).
10. Insert a funnel into the top of the burette and fill the burette using a beaker which
contains sodium hydroxide until it reaches point 0 of the burette. A beaker needs to
be placed under the burette during this step as there may be air bubbles which may
need to be released. In the case of an air bubble, the liquid should be left out in the
beaker until it has been removed. Also, the tap of the burette needs to be closed in
this step.
11. Remove the beaker from under the burette and replace it with the conical flask
which contains the hydrochloric acid and phenolphthalein as titration is ready to be
started.
3
