Unit 2 - Practical Scientific Procedures and Techniques
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Essay Unit 2 - Practical Scientific Procedures and Techniques
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Unit 2 - Practical Scientific Procedures and Techniques
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The purpose of this experiment of titration was to determine the unknown concentration of sodium hydroxide. To do this I made up a Primary standard (the Sodium Hydroxide) so this could standardise the concentration of the Hydrochloric Acid. We use Sodium Hydroxide for Our primary standard as it had...
Unit 2 - Practical Scientific Procedures and Techniques
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Chemistry Report Assignment - Charley McClellan
Task 1 ( Titration) 1
Introduction
The purpose of this experiment of titration was to determine the unknown concentration of
sodium hydroxide. To do this I made up a Primary standard (the Sodium Hydroxide) so this
could standardise the concentration of the Hydrochloric Acid. We use Sodium Hydroxide for
Our primary standard as it had a relatively large molecule mass and it's very stable it tend to
be used to standardise aqueous acids (hydrochloric,sulphur and nitric. ) Hydrochloric acid
then became a secondary standard which was used to find out the unknown of sodium
hydroxide which was 0.1 M. In chemistry, solutions used in volumetric analysis are denoted
as either primary or secondary standards.
Primary Standard is a reagent used in volumetric analysis that is extremely pure, stable, low
hygroscopicity and has a high molecular weight. Having these properties means that primary
standards are unreactive to the atmosphere and they are ready and cheaply available. In
addition, they are used to eliminate as many errors as possible. HNO3 and HCL are a
couple of examples of what wouldn’t make a good primary standard as they have a small
molecular mass meaning there would be more weighing errors and they are hygroscopic
meaning they will absorb water from the atmosphere will which affect the purity and will
cause a lot of errors when titrating.
Equipment
● Weighing balance
● Beakers
● Anhydrous Sodium Carbonate
● 200cm^3 of distilled water
● Magnetic Stirrer
● Hot plate/stirrer
● Volumetric flask
● Burette
● 100cm^3 of hydrochloric acid
● 250 ml conical flask
● 10ml Pipette
● Methyl Orange indicator
● Clamp stand
● Sodium Hydroxide
● Create secondary standards
Method for primary standard
Na2CO3 + 2HCL →NaCl + CO2 + H2O
1 Newcastle College
, 1. Check the calibration of the balance
2. Using a balance on it and re-zero, weigh out 1.062g of anhydrous sodium carbonate.
3. Add Roughly 70 cm3 distilled water,place a magnetic stirrer into the mixture and
place onto the hotplate and stir to dissolve.
4. Once the solution is fully dissolved transfer to a 100cm3 volumetric flask and top up
to the line with distilled water.
5. Use 0.1M HCL to wash and fill your burette.
6. Using a 10ml pipette transfer 10 ml of your carbonate solution to the conical flask.
7. Add a few drops of methyl orange indicator
8. Titrate your sample in till it changes from yellow to Red
9. Record your titre in a table and repeat until you and concordant titres.
Calibration Checks
Calibration means adjusting or correcting the graduations of a measuring device when
compared to a known value standard.
1. Tare a balance to zero
2. Place the 100g mass on the balance and read the mass recorded.
100g mass = 100.22g
1. Place a clean dry beaker on the balance
2. Tare a balance to zero
3. Carefully pipette 10mls of distilled water into the beaker and record its mass.
10ml of water on balance = 9.70g
Method for secondary standard
1. Wash out your burette with the standardised HCL. Then fill with the HCL.
2. Collect about 50-100ml of the unknown NaOH in a clean labelled beaker.
3. Pipette 10ml of NaOH into a 250ml conical flask.
4. Add 4 drops of phenolphthalein indicator.
5. Titrate from pink to clear, Repeat until you have three concordant titres.
Results - Primary standard
Start End Titre
0 21 21
21 44.2 23.2
44.2 64.5 20.3
2 23.2 21.2
23.2 44.2 21
44.2 61.8 17.6
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