Unit 2A
Undertake titration and colorimetry to determine the concentration of
solutions
Titration Introduction
Titration is used in industrial laboratories to determine the concentration of unknown
solutions. It involves adding a solution of known concentration (called the titrant) to a
solution of unknown concentration (called the analyte) until the reaction between the two is
complete. The point at which the reaction is complete is called the equivalence point. The
equivalence point can be detected by using an indicator, which changes colour when the
reaction is complete. Titration is widely used in analytical chemistry to determine the
concentration of acids, bases, and other substances in a solution. It is also used in industry
to monitor and control chemical reactions and in medicine to measure the concentration of
drugs in blood and urine samples.
Calibration Of Equipment
Calibration Of Pipette
To calibrate a pipette, fill the pipette to a volume of 25cm³ of water. Then release the water
into the calibrated weighing scale. The scale should read 25g as one gram is equivalent to
one cubic centimetre.
Calibration Of Volumetric Flask
To calibrate a volumetric flask, place the volumetric flask on a calibrated scale, record the
weight and fill up the volumetric flask with 250cm³ of water. Take the weight of the
flask with water and subtract it with the original weight. The scale should read 250g as one
gram is equivalent to one cubic centimetre.
Calibration Of Top Pan Balance
Take a weight of 50g and place it on the weighing scale. If the scale states that it is 50g, then
you know that the scale is calibrated properly. Do this a few times with a few more different
weights to be sure that it is correct every time.
If the scale is not calibrated, locate the calibration button of the digital scale. The button
may be labelled as: “Cal,” “Function,” “Mode,” or “Cal/Mode.” Press this button down until
the digits displayed on the scale turns to “0,” “000,” or “Cal.” Test again if it is calibrated and
set it aside to use later.
Calibration Of Burette
Pour 10cm³ of distilled water into the conical flask. Touch the tip of the burette to the wall
of the flask. Cork the flask and weigh it accurately on an analytical balance and record the
mass. The difference between this mass and the initial mass of the flask gives the mass of
the water dispensed.
Making A Standard Solution of Sodium Carbonate
A standard solution is one whose concentration is known exactly. Standard solutions of
liquids e.g. acids, are easy to prepare. They can be prepared by weighing a mass of solid and
,dissolving it in a known volume of solution in a volumetric flask. Below is the preparation of
a standard solution of sodium carbonate to use later in another practical.
Risk Assessment for Sodium Carbonate
Hazard Risk Precaution First Aid
Sodium Carbonate Serious eye and skin Wear a long sleeve In the event of a
(anhydrous solid) irritation lab coat and gloves spillage, it is
to protect your skin. essential to clean it
Also wear goggles to up immediately. Use
protect your eyes. appropriate
Use appropriate absorbent materials,
containers or vessels such as spill pads or
with lids or covers to absorbent socks, to
prevent sodium soak up the spilled
carbonate from sodium carbonate.
getting onto the Dispose of the
surrounding absorbed material
surfaces. appropriately.
If in contact with
skin rinse
immediately.
If contact with eye,
flood it with water
for 10 minutes.
Broken Glass Cuts Always keep glass in Clean the wound by
middle of table to rinsing it with
prevent it from bottled or tap water,
being knocked off or by using sterile
the table. Clear up wipes. If there is
any broken glass nothing in the
immediately. wound, put pressure
on it using a
bandage for 10
minutes. When the
bleeding has
stopped, put on a
sterile dressing or a
plaster.
Spillages Slipping Wipe any spillages Assess whether the
immediately to person is hurt and
prevent slipping. check if there are
any obvious injuries
such as bleeding or
, bruising. If there is
carry out necessary
first aid and call an
ambulance if
needed.
Apparatus
https://cdn.shopify.com/s/files/1/0093/2298/7617/files/Screen_Shot_2022-06-15_at_7.13.17_PM.png?
v=1655284422
Standardisation Method
1.Using the ± 0.1g balance, weigh approximately between 1.2g and 1.4g of sodium
carbonate into the small beaker. Do not record the mass.
2. Using the ± 0.01g balance, weigh the small beaker and its contents accurately. Record this
mass.
3. Transfer the contents of the small beaker into the large beaker. Weigh the small beaker
again using the ± 0.01g balance and record this mass. The difference between the two
accurate masses is the mass of sodium carbonate in your beaker.
4. Add de-ionised water cautiously down the side of the large beaker. Use about 150cm³ of
water and swirl the beaker to mix the contents.
Undertake titration and colorimetry to determine the concentration of
solutions
Titration Introduction
Titration is used in industrial laboratories to determine the concentration of unknown
solutions. It involves adding a solution of known concentration (called the titrant) to a
solution of unknown concentration (called the analyte) until the reaction between the two is
complete. The point at which the reaction is complete is called the equivalence point. The
equivalence point can be detected by using an indicator, which changes colour when the
reaction is complete. Titration is widely used in analytical chemistry to determine the
concentration of acids, bases, and other substances in a solution. It is also used in industry
to monitor and control chemical reactions and in medicine to measure the concentration of
drugs in blood and urine samples.
Calibration Of Equipment
Calibration Of Pipette
To calibrate a pipette, fill the pipette to a volume of 25cm³ of water. Then release the water
into the calibrated weighing scale. The scale should read 25g as one gram is equivalent to
one cubic centimetre.
Calibration Of Volumetric Flask
To calibrate a volumetric flask, place the volumetric flask on a calibrated scale, record the
weight and fill up the volumetric flask with 250cm³ of water. Take the weight of the
flask with water and subtract it with the original weight. The scale should read 250g as one
gram is equivalent to one cubic centimetre.
Calibration Of Top Pan Balance
Take a weight of 50g and place it on the weighing scale. If the scale states that it is 50g, then
you know that the scale is calibrated properly. Do this a few times with a few more different
weights to be sure that it is correct every time.
If the scale is not calibrated, locate the calibration button of the digital scale. The button
may be labelled as: “Cal,” “Function,” “Mode,” or “Cal/Mode.” Press this button down until
the digits displayed on the scale turns to “0,” “000,” or “Cal.” Test again if it is calibrated and
set it aside to use later.
Calibration Of Burette
Pour 10cm³ of distilled water into the conical flask. Touch the tip of the burette to the wall
of the flask. Cork the flask and weigh it accurately on an analytical balance and record the
mass. The difference between this mass and the initial mass of the flask gives the mass of
the water dispensed.
Making A Standard Solution of Sodium Carbonate
A standard solution is one whose concentration is known exactly. Standard solutions of
liquids e.g. acids, are easy to prepare. They can be prepared by weighing a mass of solid and
,dissolving it in a known volume of solution in a volumetric flask. Below is the preparation of
a standard solution of sodium carbonate to use later in another practical.
Risk Assessment for Sodium Carbonate
Hazard Risk Precaution First Aid
Sodium Carbonate Serious eye and skin Wear a long sleeve In the event of a
(anhydrous solid) irritation lab coat and gloves spillage, it is
to protect your skin. essential to clean it
Also wear goggles to up immediately. Use
protect your eyes. appropriate
Use appropriate absorbent materials,
containers or vessels such as spill pads or
with lids or covers to absorbent socks, to
prevent sodium soak up the spilled
carbonate from sodium carbonate.
getting onto the Dispose of the
surrounding absorbed material
surfaces. appropriately.
If in contact with
skin rinse
immediately.
If contact with eye,
flood it with water
for 10 minutes.
Broken Glass Cuts Always keep glass in Clean the wound by
middle of table to rinsing it with
prevent it from bottled or tap water,
being knocked off or by using sterile
the table. Clear up wipes. If there is
any broken glass nothing in the
immediately. wound, put pressure
on it using a
bandage for 10
minutes. When the
bleeding has
stopped, put on a
sterile dressing or a
plaster.
Spillages Slipping Wipe any spillages Assess whether the
immediately to person is hurt and
prevent slipping. check if there are
any obvious injuries
such as bleeding or
, bruising. If there is
carry out necessary
first aid and call an
ambulance if
needed.
Apparatus
https://cdn.shopify.com/s/files/1/0093/2298/7617/files/Screen_Shot_2022-06-15_at_7.13.17_PM.png?
v=1655284422
Standardisation Method
1.Using the ± 0.1g balance, weigh approximately between 1.2g and 1.4g of sodium
carbonate into the small beaker. Do not record the mass.
2. Using the ± 0.01g balance, weigh the small beaker and its contents accurately. Record this
mass.
3. Transfer the contents of the small beaker into the large beaker. Weigh the small beaker
again using the ± 0.01g balance and record this mass. The difference between the two
accurate masses is the mass of sodium carbonate in your beaker.
4. Add de-ionised water cautiously down the side of the large beaker. Use about 150cm³ of
water and swirl the beaker to mix the contents.
