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BTEC National Extended Diploma: Unit 2
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- PEARSON (PEARSON)
Comprehensive assignment on the unit 2 assignment on titration of BTEC National Extended Diploma in Applied Science which was rewarded a disctintion.
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BTEC Level 3 Extended Diploma in Applied Science Assignmentgrade achieved
D
Keeping up the standards
Titration is a scientific technique where we can find the concentration of an unknown substance by
the slow addition of a chemical with a known concentration. This careful addition of the substance with a
known concentration, known as the titrant, is added until the reaction reaches neutralisation.
The technique of titration has many uses outside the laboratory; used in pharmaceutical industries to
manufacture medicines and to adjust dosage, to water companies where titration is vital to analyse the safety
of drinking water based on its chemical elements.
By following this technique, we can find the concentration of our unknown chemical,
sodium hydroxide (NaOH) by adding hydrochloric acid (HCl) which is the titrant in the reaction and has a
concentration of 0.1 mol/dm3 .
Apparatus and Materials:
50ml Burette
25ml bulb pipette
Pipette Filler
250cm3 Conical Flask
100ml beaker
Clamp and Stand
Wash bottle
Funnel
Balance
Weighing boat
Spatula
Methyl orange Indicator
Standard hydrochloric acid mold/dm-3
Sodium hydroxide
Sodium hydrogen carbonate
Preparing equipment: Calibration
The calibration of the equipment starts with the burette, where the burette was conditioned for the
titration practical by being cleaned with the titrant solution (HCl). The burette was cleaned with the titrant
solution rather than distilled water as distilled water offers a greater chance the hydrochloric acid would be
distilled—changing its known concentration and effectively ruining the investigation.
The calibration of the equipment started with the burette which was first calibrated with distilled
water:
Equipment used for calibration of burette:
Wash bottle
Burette
Waste beaker
Plastic water bottle
Stand and clamp
Deionised water
1. A waste beaker was placed beneath the tap of the burette before the burette was rinsed through with
deionised water.
a. A waste beaker was used to avoid any spillages
2. The outside of the burette was then wiped down with paper towels.
3. The burette was then inspected to ensure no water droplets remained inside.
a. Any water droplets remaining in the burette would indicate it being unclean.
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,BTEC Level 3 Extended Diploma in Applied Science
4. The tap of the burette was closed before it was filled with deionised water above the 0 mark.
5. The tap of the burette was then opened to release any trapped air and to lower the water level down
to 0.00ml.
a. The meniscus was ensured to have reached the 0 mark.
6. The empty plastic bottle was then weighed on the balance
a. This weight was then recorded.
7. Beneath the tap of the burette, the plastic bottle was placed before water was released until the
10.00ml mark.
a. The initial and final reading of the burette were recorded.
8. The plastic bottle with 10.00ml water was then reweighed on the balance.
a. This weight was recorded.
9. The plastic bottle with 10.00ml water was then placed beneath the burette and the burette tap
released water to the 20.00ml mark.
a. The final burette reading was then recorded.
10. The plastic bottle was weighed again with 20.00ml water on the balance.
a. The weight of the bottle was then recorded.
11. This process was repeated in 10.00ml increments until the full 50.00ml of water had been dispensed
from the burette.
12. A calibration curve was created based on the data received.
a. The calibration curve offered an absolute error of the burette.
Calibration of the bulb pipette
Equipment used for calibration of burette:
Bulb pipette
Pipette filler
Deionised water
Waste beaker
50ml beaker
Wash bottle with deionised
1. The calibration of the bulb pipette began by running deionised water through the bulb pipette.
2. The outside of the bulb pipette was dried with paper towels.
3. The bulb pipette was then inspected for any water droplets
a. If there were any water droplets present this would indicate the bulb pipette would be
unclean.
4. The bulb pipette was then inspected to ensure there were no residual water on the outside of the bulb
pipette.
5. Then a clean 50ml beaker was weighed on a balance
a. This weight was recorded.
6. Using the bulb pipette, water was taken up past the volumetric line.
a. The tip of the bulb pipette was ensured to not touch the bottom of the beaker as the tip of the
bulb pipette was very fragile.
7. The pipette filler was released off the bulb pipette before water was dispensed so the water line
reached the volumetric line.
8. The water from the bulb pipette was released into the 50ml beaker that was weighed before.
9. The mass of water transferred was determined using the balanced.
10. The mass of water transferred was then compared to the mass of water that should have been
transferred with the bulb pipette.
11. This process was repeated three times total.
a. These results were averaged and offered the absolute error of the bulb pipette.
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, BTEC Level 3 Extended Diploma in Applied Science
The burette was also checked for air bubbles which would not give an accurate reading of the
hydrochloric acid. Air bubbles within the burette were removed by gently flicking the burette.
Similarly, the bulb pipette used in the investigation was also conditioned through being cleaned
with the alkali of sodium hydroxide instead of distilled water as it could affect the concentration of the
sodium hydroxide which was added later.
Scales used in the titration practical were also calibrated, one way this could have been done
using accurate masses. However, the scales used in the titration investigation were externally calibrated by a
professional organisation.
Making a Standard Solution:
A standard solution was created before the titration between hydrochloric acid and sodium hydroxide
to determine the exact concentration of hydrochloric acid. The standard solution that was used in the
practical was 2.1 grams of sodium hydrogen carbonate (NaHCO3) which was then titrated with hydrochloric
acid to be certain of its concentration.
Making a standard solution is that which contains a known mass of a pure solute dissolved in a
solvent to offer a specific volume which is then utilised to calculate the concentration of the hydrochloric
acid.
Creating a standard solution is vital for the reliability for the titration practical as with it, the
concentration of the hydrochloric acid was determined correctly and used for the titration between sodium
hydroxide and hydrochloric acid.
Equipment and materials for standard solution:
50ml burette
25ml bulb pipette
Pipette filler
250ml Volumetric flask
100ml beakers (x2)
Filter funnel
Spatula
Sodium Hydrogen Carbonate
Weighing boat
Balance
Glass Rod
Wash bottle of distilled water
Method for making a standard solution of NaHCO3:
Once the equipment was attained, the glassware such as beakers and flasks were checked for chips
and cracks.
The target mass of sodium hydrogen carbonate for the standard solution was calculated to be 2.1:
1. The Mr of NaHCO3 was found to be 84
2. The concentration of NaHCO3 was known to be 0.1 mol/dm3 and this was used to find the moles of
sodium hydrogen carbonate.
3. The volume of NaHCO3 was 250ml that was converted to 0.25dm3
4. The concentration and volume of sodium hydrogen carbonate was used with the formula
mol=concⅇntratⅈon × volume to find the mole of NaHCO3 which was found to be 0.025.
5. Using the moles and Mr of NaHCO3, the mass was found by using the formula mass=mol × mr
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