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Keeping up the standards - 2A Applied science
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- 2A Applied science
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- PEARSON (PEARSON)
Btec applied science - national diploma - chemistry- distinction
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TitrationsIntroduction
In this assignment the aim was to determine the unknown concentration of sodium hydroxide and
Sodium carbonate. I used titration, colorimetry, and pH probe to figure out the concentration of an
unknown solution and used my results for calculating the unknown solution. A chemical solution with
a specific concentration is known as a standard solution. A solution with known concentration is
standardised in the same way. A known mass of solute is dissolved and diluted to a certain amount to
make a standard solution.
Calibration
In this experiment I am using water as a standard for checking the calibration of volumetric
equipment. To measure the effectiveness of each object and which equipment would be suitable for
my titration experiment.
Equipment:
Pipette
Burette
50cm3 beaker
25cm3 measuring cylinder
Distilled water
Balance
Paper towel
Method:
Make sure a balance is at Zero.
Place a 50cm3 beaker on the balance and measure the mass.
Extract 25cm3 distilled water from a pipette to the beaker and measure the mass.
Then calculate the mass of water extracted
Get rid of the water and dry the beaker thoroughly with paper towel.
Repeat this 1-5 for 25cm3 from step 3 for a burette, 50cm3 beaker and a 25cm3 measuring
cylinder.
Pipette Burette 50cm3 beaker 25cm3
measuring
cylinder
Mass of beaker
plus 25cm3 57.37 57.49 56.12 55.06
water(g)
Mass of empty
beaker(g) 32.42 30.79 32.27 32.12
Mass of 25cm3
, water(g) 24.95 26.70 23.85 22.94
Temperature of Density of water Volume(cm3)
water (g/cm3)
Pipette 18°C 0.9985 24.95x0.9985=24.9
Burette 18°C 0.9985 26.70x0.9985=26.6
Beaker (50cm3) 18°C 0.9985 23.85x0.9985=23.8
Measuring cylinder 18°C 0.9985 22.94x0.9985=22.90
(25cm3)
Evaluation: Results
In this experiment I used scientific equipment such as a pipette, burette, 25cm3 measuring cylinder
and a 50cm3 beaker to check the calibration of volumetric equipment. I used calibration to carry out
this assessment to measure the accuracy of the device and how it determines the accuracy of the size
and to make certain correct results in all laboratory settings. The measurements of the pipette could
have been affected by air bubbles and the possibility of the mass of water being measured was not
reached in pipette.
In this assessment using a pipette was more effective than the burette 50cm3 beaker and 25cm3
measuring cylinder to carry out other experiments. The pipette will be better to use in laboratory
settings because it is precise when delivering solutions as it has a narrow neck, this permits for the
meniscus to be read with more precautions, and therefore deliver more specific results. Both 50cm3
beaker and 25cm3 measuring cylinder are not in the range mass of water needed.
The least effective apparatus was the 25cm3 measuring cylinder with 22.94cm3 of water, this may be
because of spillage of water during experiment, their lack of precision may be because of their large
meniscus and imperfections in the techniques used to make measurement. The burette went over the
required mass, this may be because of lack of accurate mass of water used and more water was used
than intended.
There are certain factors that affect the calibration of volumetric apparatus and their measurements.
The environment where tests and calibrations are done can have an influence on uncertainty in
dimension results. Variables along with temperature, humidity, strain, gravity, elevation, vibration,
strain, stress, lights, and so on. can impact the measurement results. The quality of calibrators can
influence the effectiveness of equipment used in calibration. Only calibrators constructed to express
tolerances and specifications ought to be used for getting repeatable results and overall performance.
Another factor, the use of the wrong values produces mistakes within the operating range of the
equipment. This could lead to inaccuracy of my titration experiment such balance (weighing error),
temperature and abrasion of burette.
Calibration of a balance
Method
· Tare a balance
· Add 50g and 100g weights and record the mass
· Check values are within margin of error
Results
, Weight (g) Reading on balance (g)
50 50.00
100 100.03
Errors for the titration of Na2CO3 with HCl
· % error from balance = (0..65) x 100 = 0.019%
· % error from volumetric flask = (0.2/250) x100 = 0.08%
· % Bulb pipette = (0.06/25) x100 = 0.24%
· % Burette = ((3x0.05)/ 15.05) x100 = 0.99%
Total error on your calculated value of HCl = 0.019 +0.08+0.24+0.99= 1.329
Errors for titration of NaOH with HCl
· % Bulb pipette = (0.06/25) x100 = 0.24%
· % Burette = ((3x0.05)/ 24.9) x100 = 0.60%
Total error on your calculated concentration of NaOH = 0.24 + 0.60 = 0.84%
Conclusion
Factors affecting the accuracy of a balance
An inaccurate balance can affect my titration results as equipment and masses of solution will not be
accurate affecting concentration and moles results. This could lead to having results which are not
precise. My titration results will have irregular runs. The type of balance used can affects my titration
including the units such as the placement; the surface needs to be flat to ensure accuracy is precise
and to ensure there is no rocking this is so the levelling will be stable.
Colorimetry: Copper sulphate
Equipment:
Ground ore (copper containing copper carbonate)
Sulphuric Acid
250cm3 beaker
100cm3 volumetric flask
Burette
Copper sulphate solution
6 Boiling tubes
Googles
Method:
1. Weigh out 10g of ground ore and transfer to a 250cm3 beaker.
2. Add 40cm3 of the dilute sulphuric acid in small amounts, allowing fizziness to subside between
additions.
3. Once the reaction is completed filter the mixture making sure that the cooper solution is filtered.
4. Add the filtrate and washings to a 100cm3 volumetric flask.
5. Then add purified water so that the volume of liquid in the flask is 100cm3.
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