Unit 2- Practical Scientific Procedures and Techniques
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Applied science, unit 2A
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Unit 2- Practical Scientific Procedures and Techniques
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PEARSON (PEARSON)
Distinction grade 2A assignment, includes all the relevant information for pass, merit and distinction. Use this as a template for your own assignment and to learn the key points you should make in your own to get a distinction first try.
Unit 2- Practical Scientific Procedures and Techniques
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Instrument calibration: Calibration of a scientific instrument helps to maintain its accuracy. The procedure entails using an instrument with known values. This causes the
instrument to produce more accurate results.
Titration is an analytical technique that uses a standard solution to determine the concentration of an unknown solution. A titration is a method of determining the concentration
of a solution by reacting it with a known concentration solution and measuring the volume required for a complete reaction.
The number of moles in the standard solution is calculated using a balanced equation for the reaction; the number of moles in an unknown concentration solution can also be
calculated; once the number of moles for the solution is known, the concentration can be easily calculated.
The concentration of a solution is the amount of solute dissolved per unit of solvent.
The concentration formula is: - Amount of solute/Volume of solvent C = n/V).
The amount of solute is expressed in moles. (n = number of moles or solute amount)
Solvent volume is measured in dm3. (V = solvent volume)
The concentration is expressed in mol/dm. (C stands for concentration.)
Because volume is frequently expressed in centimetres, a more useful equation includes a conversion from centimetres to decimetres. (1dm3 =1000cm)
A standard solution is one with known concentrations. Using a volumetric flask, a standard solution is created by dissolving an accurately weighed mass of solvent in a known
volume of solvent. The volumetric flask has a thin Rack marked with a line that allows it to be filled precisely to the correct capacity. The process of determining the exact
concentration (molarity) of a solution is known as standardisation. The concentration of a second solution with which it reacts can then be determined using the standard solution.
Volumetric analysis or titration is the term for this.
Risk assessment of chemicals
Methyl orange may contain one or more of the following H statements: It is fatal/toxic if swallowed (H300/H301). Fatal/toxic in skin contact [H310/H311). It is fatal/toxic if inhaled
[H330/H331). [H314] Burns the skin and damages the eyes. [H318] It is extremely harmful to the eyes. It may cause allergy or asthma symptoms, as well as breathing difficulties, if
inhaled (H334). [H340] This could lead to genetic defects. H350 could cause cancer. It is possible that it will harm fertility or the unborn child (H360). Organ damage occurs [H370].
Organ damage results from long-term or repeated exposure (H372).
When using sodium carbonate, consult the most recent recommendations and use safer alternatives whenever possible. Wear safety glasses. Compositions will affect properties,
so always test activities with new stock. Examine the information provided by the supplier. If you have any doubts, please contact CLEAPSS. Avoid inhaling or raising dust. A fume
cupboard is used to transfer or dispense solids and to prepare solutions. Other notes can be found here. Skin contact should be avoided at all costs. See activity-specific guidance
and/or GL 120 for more information. Gloves are recommended in a variety of situations, not the least of which is to prevent hand staining. Wash your hands thoroughly after use.
Spills should be cleaned up as soon as possible, and any residues should be disposed of. The risk of dust/dust inhalation is increased by dried spills, but the quantities are small,
given that solutions are typically less than or equal to 1%.
When preparing the Na2CO3, prepare dye, indicator, or stain solutions (TT only). Open containers in a working fume cupboard, then turn it off. Much depends on the substance's
formulation and the prepared solution. To transfer or weigh out the solid, consult activity-specific guidance, Recipes, and/or supplier information. Pull the sash partially down.
Refer to Recipes and/or other guidance for detailed information on the preparation, labelling, and storage of specific dye/indicator/stain solutions. For students, use the following
dye, indicator, or stain solutions: Solutions contain less than 1% of the dye/indicator/stain material and are thus less hazardous, though the solvent (and/or other reagents) may be
flammable and/or pose additional hazards.
, Hydrochloric acid is a dangerous liquid that must be handled with caution. The acid itself is corrosive (opens in a new tab), and concentrated forms emit dangerous acidic mists. If
the acid or mist meets the skin, eyes, or internal organs, the damage can be irreversible, and in severe cases, fatal. Personal protective equipment (opens in a new tab) is required.
At levels found in consumer products, Na2CO3- Sodium carbonate is a Generally Recognized as Safe chemical with a minimal risk of toxicity in humans. Prolonged contact with
sodium carbonate may cause eye, skin, and airway irritation. irritate the eyes severely. Because anhydrous solid is finely powdered, it poses a greater risk than hydrate, which is
crystalline (large crystals). Soda dust is a contaminated (industrial) form.
Sodium hydroxide concentration method
To do this, I must first prepare a standard sodium carbonate solution that I will use as a base for the remaining calculations in this experiment, increasing their accuracy and
reliability and allowing me to use it in the titration I will perform later. Because the only piece of equipment we use in Part 1 is a balance, you must first calibrate it. To do this, use
an analytical balance and see if the result falls within the tolerances of the masses. Tolerances for 1g should be equal to or less than 0.001g, 10g tolerances should be equal to or
less than 0.002, 20g tolerances should be equal to or less than 0.004g, and so on. Finally, for 50g, the tolerance should be + or -0.008g. Our balance could only be recorded up to
two decimal places, rather than the required three.
Mass of 1g Within the Mass of 10g Within the Mass of 20g Within Mass of 50g Within the
tolerance? tolerance? The tolerance
tolerance?
1.00g Yes 10.00g yes 20.00g yes 50.01g no
normally this would lead to us having to calibrate the scales so that the mass would be within the tolerances of 50g but as we only used 1.34g so we did not have to.
Mass of weighing boat and Na2CO3 2.51g
Mass of weighing boat 1.17g
Mass of Na2CO3 1.34g
Class comparison
me Sydnee Sam Sophie Keira average
1.34 g 1.22g 1.30g 1.38g 1.22g 1.29g
My results were close to the average class results which means that my results were quite accurate.
Equipment used:
Weighing boat – use this to hold the sodium carbonate when you weigh it, ensure you check for cracks and make sure that its clean to get the most reliable results.
Balance - use to weigh out the sodium carbonate, make sure you tare it after you weigh the boat, make sure it is on the correct settings and calibrate it effectively. +-
0.01g
Volumetric flask – use this to hold and fully mix the sodium carbonate and water, make sure to check for cracks and rinse out with distilled water before use to reduce the
risk of contamination +-0.2cm3
Glass rod - use to stir the sodium carbonate and water. Rinse with distilled water before use to get rid of contaminants
2
BTEC Assignment Brief v3.0
BTEC Internal Assessment QDAM December 2017
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