Unit 2- Practical Scientific Procedures and Techniques
Institution
PEARSON (PEARSON)
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Unit 2- Practical Scientific Procedures and Techniques
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Chemistry report
Practical scientific procedure and technique
Context: You are a newly appointed technical assistant than large chemical plant chemcalequip. A
part of your induction and period progress in your role, you have to demonstrate skills in a range of
practical procedures and techniques. Part of your role is to ensure equipment is calibrated and
equipment and chemical safety checked. A key part of your job will be making and testing standard
solutions using titration and colorimetry procedures. You must demonstrate your ability to carry out
these techniques skillfully and accurately. Evidence of your practical skills along with your results,
calculation, evaluation of the technique and possible improvement will be submitted in the report
Task 1: preparing a standard solution
Equipment
Boat, spatula, glass rod, funnel, digital mass, distilled water in wash bottle, one 250cm³ beaker and
one 250cm³ volumetric flask
Chemical
Na2CO3- it is an irritant
Healthy and safety
Lab coat to be worn with safety glasses
hazard warning and safety sign to be read before any work
Bags or coat must be kept under bench or completely out of the way
Spills or accident must be told to a teacher. Rinse skin instantly if any chemical touches
Broken glass must be cautiously place in the yellow glass bin provided
Method
Firstly, I calibrated the balance using mass of different weight ranging from 0.01g, 0.1g, 10g, 100g
until all reading are correct and if not recalibrate until correct. I then places a boat filled with
anhydrous sodium carbonate measuring around 1.25g to 1.45g and place it on the balance to weigh
it (I got 1.35g for this part. After weighing I transferred the anhydrous sodium carbonate to a beaker,
filled around 150cm³ of distilled water and used a glass rod to stir until dissolved. When it finishes
dissolving I poured the dissolved solution into a 250cm³ volumetric flask then added ionized water
until it hits the graduated mark. I made sure not to overshoot it as you will need to start all over
again. I put a stopper on the volumetric flask to prevent a pillage then shake it to properly mix the
content of the flask. Once done, I cleaned up my environment then calculated the concentration in
mol/dm³
Errors that might appear when doing the preparing the standard solution is that the weight of the
sodium is not measured correctly or the sodium carbonate did not dissolve properly. When I was
doing the standardization, I had a problem of over shooting the water in the volumetric flask causing
me to restart the practical over again.
Good measurement practice in standard solution
Observing good practices in preparing standard solution can help reduces error made and ensure
accurate results. Good practices such as cleaning equipment with correct reagent or ensuring that
the equipment is dry before using it can ensure quick and efficient work. The practices that I
observed is when I was filling up the volumetric flask, I used a pipette to prevent over shooting and I
mixed the solution vigorously to allow the chemicals to dissolve. Pay attention to spills when
weighing the sodium carbonate as it will affect the reading
Task 2: Standardization of Hydrochloric acid
Equipment
Funnel, pipette filler, burette, wash bottle filled with distilled water, stand and clamp, 250cm³ conical
flask, 25cm³ pipette, 2 250cm³ of beaker
Chemical
Methyl orange indicator is a combustible solution
Hydrochloric acid solution(150cm3) can cause irritation
Standard sodium carbonate solution(150cm3) can cause irritation
Health and Safety
, Lab coat to be worn with safety glasses
hazard warning and safety sign to be read before any work
Bags or coat must be kept under bench or completely out of the way
Spills or accident must be told to a teacher. Rinse skin instantly if any chemical touches
Broken glass must be cautiously place in the yellow glass bin provided
Method
1) I first celebrated the pipette and the brunette;
I first weighted a dry flask then wrote down the mass, I then used distilled water to fill up the burette
until it hits the graduated mark. After hitting the graduated mark, I transfer the distilled water to a
conical flak then found out the density of the distilled water and difference between the mass of the
conical flask from the water.
The difference between the mass of conical flask from water
Mass of the conical flask= 119.88g
Mass of the conical flask and distilled water= 170.57g
Mass of the distilled water= 50.09g
Volume of the distilled water
Density= mass/volume
Volume=mas/density
The volume obtained most be close to the volume of the conical flask which is 50cm³
2) Secondly, I calibrated the pipette;
I weighed a dry flask and wrote down the mass. I then used ionized water to fill up the
pipette to the graduated mark. After filling it to the mark, I transferred the distilled water to
the to a beaker and recorded the mass. Using the result written down, I found the volume of
water and mass of the water.
mass of the water by differencing the mass of the beaker by the mass of the beaker and
distilled water
Mass of the beaker=116.80g
Mass of the beaker and distilled water= 141.8g
Mass of the distilled water= 25.00g
Then I found the volume of the water in the pipette using this formula
Density=mass/volume
Volume=mass/density
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