Unit 2 - Practical Scientific Procedures and Techniques
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Unit 2: Assignment 4 - Evaluation of Skills
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Unit 2 - Practical Scientific Procedures and Techniques
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PEARSON (PEARSON)
Final assignment for Unit 2 Practical Techniques detailing practical, personal and interpretative skills acquired through all the practicals conducted thought the course. There are 4 skills for each practical: titrations, colorimetry, calorimetry and chromatography. Received a distinction for this ...
Unit 2 - Practical Scientific Procedures and Techniques
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1. Introduction
It is important in all scientific professions to retain the proof of ongoing professional growth.
If people want to make the most of their experiences and develop their skills for the future,
they must reflect on past experiences. Following this, we have been introduced to various
practical’s, including titrations, colorimetry, calorimetry, and chromatography since the
beginning of this course. As a result, I've developed a variety of practical, personal and
interpretative skills. Recognising our errors allows us to make improvements to our
techniques so that we can achieve better results. So, the more we make mistakes, the quicker
we can learn and gain knowledge that we can use to strengthen our personal, practical, and
interpretative skills.
2. Titrations
Practical Skills
I had never done any titration practical’s before starting this course, so I was unfamiliar with
the equipment and how to use it correctly to achieve accurate, valid, and reliable results. The
bulb pipette is one of the most important pieces of equipment required for this practical. The
bulb pipette, also known as a volumetric pipette, is a glassware tool used to precisely measure
liquid volumes. The cylindrical or bubble form in the centre of the main thinner cylinder is
the main attribute that gives the pipette the name "bulb" pipette. A pipette filler is required to
draw liquid up the pipette. I had never used this equipment before either, so I made a few
mistakes at first. To avoid breaking the glassware, carefully place the pipette filler on top of
the bulb pipette. One hand should be on the pipette filler and the other should be on the bulb
pipette for support. Furthermore, the tip of the pipette should not be pushed against the work
surfaces, as this may cause damage. I may have caused damaged the pipette when practising
using this equipment at the beginning of the year because I did not properly support the
pipette. To improve in the future, I should have more of a general care and awareness of the
glassware I am using and being more focused on what I am doing to prevent any slight
mistakes in the handling of the equipment. Subsequently, through practice throughout the
year in other practical’s I have learned to correctly use this equipment and believe I am good
at this skill can use this in the future to gain accurate results in other investigative practical’s.
Reading volumes from a burette was another practical ability I had no prior experience with
and so it was not a skill I was competent in. The burette is an important piece of titration
equipment since it allows an acid to be slowly introduced into an alkaline solution to
determine the volume of acid needed to neutralise the base. If the volumes read from the
burette were incorrect, the subsequent calculations would be incorrect as well, yielding an
inaccurate result. As a result, I needed to learn how to read these volumes correctly as soon as
possible. The correct way to read the volume from a burette is to use the meniscus. A
meniscus is a curved surface at the top of the liquid level. The bottom of the meniscus is used
to determine the liquid volume. The surface tension of the liquid creates the meniscus and is
more accurate than reading from the liquid at the sides of the burette (also called the upper
meniscus). During the first titrations, I conducted I was reading the volumes from the upper
meniscus and so my later calculations were not as accurate as they could have been. I was
then provided with feedback from my tutor on how to correctly read the volumes and I
, worked on this skill. Due to the number of times be repeated investigations and practised
titrations I am now confident that I can accurately read the volume presented on a burette.
This skill can now be used in other practical’s where either a burette is needed or where
volume needs to be read where a meniscus is present.
Personal Skills
During the titration practical I worked independently and so when issues arose with the
equipment and results, I was the only person responsible. In the pH titration, the
phenolphthalein applied to the hydrochloric acid turned cloudy. This was unexpected, and the
work I had produced thus far was contaminated as a result. Since phenolphthalein is
colourless in acids and pink in base solutions, a cloudy precipitate is a good indicator that the
phenolphthalein batch is no longer acceptable to use. To correct this, a fresh conical flask of
hydrochloric acid was used with a new batch of phenolphthalein. To avoid using cloudy
batches of phenolphthalein in the future, batches should be tested regularly. However, when I
was conducting the practical, I failed to notice this and used the indicator. I accepted that I
was the person at fault for this and I restarted the practical to prevent further contamination
and gain valid results. Being able to accept that I was at fault for not recognising the issue
before it escalated is a valuable skill as it helps us grow personally and make fewer mistakes
in the future. It's important to take responsibility when things go wrong if you want to build
confidence with others and learn from your mistakes. To improve further I could make a list
of issues I have face and how I resolved them to prevent the mistake from happening again.
This is a skill that I believe I am competent in and can and will apply outside of college and
in future jobs as taking responsibility for my own work demonstrates maturity and gives
future employers trust that I can accept when I am wrong and work to resolve the issue.
Interpretative skills
Titrations revolve around the use of potentially hazardous chemicals that could cause serious
harm to health if not properly handled. There are set legal regulations and lab practices that
are mandatory to follow at all times. I was aware of some traditional laboratory practises
prior to beginning this course, such as tucking in chairs, hair tied back, goggles worn if
appropriate, and how to stay safe around Bunsen burners, but I was unaware of the
regulations or some of the other laboratory practices. Some of the safe working practises I
was unfamiliar with included the level of personal protective equipment required; I had never
had to wear lab coats, gloves, or goggles before. Wearing personal protective equipment
provides a barrier between us and potentially harmful chemicals, which protects both us and
our fellow students by avoiding direct skin contact. Additionally, the Control of Substances
Harmful to Health Regulations 2002, or COSHH, is the law that governs the handling of
hazardous chemicals. This regulation, according to NWLDC 2021, requires that any
substance found be evaluated for its risks, precautions be taken, and continuous control
measures be used. The health risk is significantly reduced by detecting and monitoring
interaction with potentially dangerous substances. In relation to a laboratory setting, the
substance is usually known but the risks still need to be monitored and procedures
implemented to reduce the risk to health. By knowing the potential risks, we can equip
ourselves appropriately, for example, by implementing the use of personal protective
equipment. I now realise how important it is to protect myself from chemicals and other
hazardous substances and now feel I am confident in implementing safe working practices.
Improvements can be made by familiarising myself with which chemicals are dangerous and
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