The assignment achieved a Distinction Star grade due to its clear presentation, accurate data analysis, and insightful conclusions. The student determined the concentration of an unknown hydrochloric acid solution using sodium hydroxide as the titrant, achieving precise and consistent results acros...
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 .
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.
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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