This is my assignment for Unit 2 Learning Aim A, which received a distinction grade. It is 31 pages long, so it is very detailed, and it will guarantee you a distinction grade.
Undertaking titrations and colorimetry to determine the concentration of solutions
The aim of this assignment is to undertake titrations and colorimetry to determine the concentrations of
unknown solutions. I will be preparing and standardising solutions for titration and colorimetry and will
be demonstrating skillful applications of procedures and techniques in titrations and colorimetry to
accurately determine the concentration of these solutions. Finally, I will be evaluating the accuracy of
the procedures and techniques used during titrations and colorimetry practical’s in relation to the
outcomes and will be suggesting methods of improvements that could be made to further accuracies
these results.
What is calibration and what is its importance?
Calibration is a way of checking accuracy of our measurements. The process involves using instruments
with known values as it ultimately ‘teaches’ the instrument to produce values that are more accurate.
Calibration is important because it helps ensure that measurement devices and systems are accurate
and reliable. Inaccurate measurements can lead to incorrect decisions, poor quality products, and
potential safety hazards. Calibration helps to reduce measurement errors and uncertainties, which in
turn improves the quality and reliability of products and processes.
Why is calibration so important? - labfacility (no date) importance of calibration. Available at:
https://www.labfacility.com/media/productattach/w/h/why_is_calibration_so_important.pdf
(Accessed: April 12, 2023).
Calibration of a balance-
In order to calibrate a balance, you take a standard weight and measure the mass. The measurement of
the standard mass should be within a tolerance range.
Equipment list-
Weighing boat
Balance
Weights
Method-
1. Switch on the balance and allow it to reach thermal equilibrium.
2. Ensure the number on the balance is at zero to start off. This is to avoid errors that may affect
the results.
3. The surface that the balance is placed on should be flat to allow for accurate readings to be
achieved.
4. Place a 10g mass on the scale.
5. Note down the reading and the tolerance (0.05) to see if the results you obtain are within the
tolerance.
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6. Repeat two more times with the 10g mass so that an average can be taken and repeat this
method with the 20g mass and the 100g mass.
The results were precise as a result of the calibration of the balance, and no calculations were required
to improve the results. The results were within the expected range, making it reliable. Calibrating a
balance is critical because properly calibrated balances produce accurate results and reduce the
likelihood of weighing errors.
The accuracy of a balance can be affected by many factors such as the surface the balance is placed on,
draughts, the ambient temperature, vibrations, the time it takes for a scale to ‘warm up’, magnetism
and static electricity.
Calibration of a pipette-
The ability to precisely measure the volume of a solution is crucial for the accuracy of chemical analysis.
To minimise problems, we can calibrate the glass by weighing the mass of the water. Weighing can be
done with very good accuracy and by knowing the water density, we can calculate the volume of the
given water mass.
equipment list-
volumetric pipette
distilled water
beaker
balance
method-
1. record the temperature of the room.
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2. place an empty beaker on the balance and tare the balance.
3. Use a pipette to measure 25cm3 of water.
4. Gently dry the pipette with a paper towel.
5. Transfer the 25ml of water into the beaker.
6. Record the mass off the balance.
7. Use the density table and mass of the water to calculate the volume.
8. Compare your answers to the volume measured.
9. Repeat steps 1-4 3 times to ensure accuracy.
10. Evaluate the accuracy of the pipette based on the results collected.
11. If the pipette is accurate, the water should weigh between the value of 24.9252g.
Conclusion-
The distilled water was transferred into the weighing bottle and was weighed. The difference in mass
was calculated and the mass of water was weighed to be 24.97g. the laboratory was 18 °C so the density
of the water at that temperature is 0.99862 g/cm3 (according to the International Critical Tables Of
Numerical Data, Physics, Chemistry and Technology, vol III). Using volume= mass x density, the volume
of water from the pipette was 24.97g x 0.99862= 25.0045 cm 3
Part 1: Preparation of sodium carbonate standard solution-
A standard solution contains a precisely known concentration of an element or substance. A known
weight of solute is dissolved in the solvent to make a specific volume. The aim of this experiment was to
make a 0.1M concentration of sodium carbonate accurately using the correct scientific method.
equipment-
2.65g of sodium carbonate
Balance
Spatula
Beaker
Wash bottle
Stirring rod
250ml flask
Distill water
Stopper
Weighing boat
Funnel
Risk assessment and hazards-
Sodium carbonate used in the experiment is an irritant. This means it can cause irritation to the skin and
eyes if it gets in contact. Some measures to take in order to reduce the risk of this happening is to
ensure you use the smallest amount of substance required and seal whatever is not in use to reduce the
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risk of it contacting the skin. Wearing eyes protection such as goggles helps protect the substance from
entering the eyes and when the solution is being diluted in water, it should be stirred frequently to
ensure good mixing.
Student Safety Sheets 33 - CLEAPSS (no date) Sodium Carbonate Risk Assessment. Available at:
https://science.cleapss.org.uk/Resource/SSS033-Sodium-and-calcium-carbonates.pdf (Accessed: April
12, 2023).
If the substance does contact the skin or eyes and becomes an irritant, run eyes through warm water for
20 minutes immediately and if in contact with skin or clothes, remove contaminated clothing and gently
run the affected area under tap water for 20 minutes.
The volumetric flask used in this experiment is made of glass which could be a health and safety hazard
if broken. In the case of a flask breakage, there is a risk of being cut so it’s important to take precautions
and not handle the broken pieces. In the case of a cut its important for the person to seek medical
attention immediately or as an alternative run the affected area under cold tap water for 20 minutes.
Part C introduction to risk assessment templates - health and safety ... (no date) Risk Assessment of
Glassware. Available at: https://www.hsa.ie/eng/education/managing_safety_and_health_in_schools/
new_guidelines_files/PartC.pdf (Accessed: April 12, 2023).
The weighing balance may cause electrical shocks so its important that you avoid touching any exposed
conductors. In the case of a shock, seek medical advice immediately.
Diagram of equipment-
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Method-
1. Tare the balance with the empty weighing boat.
2. This is done to make sure that the balance is calibrated to ensure accuracy of results obtained.
3. Weigh out 2.65g of sodium carbonate using a spatula.
4. Keep the sodium carbonate away when not in use to prevent contamination.
5. Transfer to a beaker ensuring you wash out the weighing boat using a wash bottle to ensure all
the powder is transferred.
6. Dissolved the powder in distilled water.
7. You only need enough water to dissolve the solute. Do not put more than 250cm 3 of water in.
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