Unit 2D practical scientific procedures and techniques
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Course
Unit 2; Practical scientific procedures and tech
Institution
PEARSON (PEARSON)
It is an assignment for unit 2 part D. This assignment has receieved distinction.
drawing on examples of skills developed in
colorimetry, titration, calorimetry and
chromatography in this unit and how they can be
transferred for use in other units.
working to appropriate standards and...
Unit 2D
Hijab Zahra
Skills developed in Colorimetry:
Using a colorimeter:
It allows light to pass through to determine the concentration of a substance. When
using a colorimeter, we use cuvette. Cuvette consists of smooth and rigid sides. 2
sides are rigid, and 2 sides are smooth. When placed into a colorimeter it should be
placed front to back from where the beam of light can be passed. I added the
cuvette, but rigid sides were front to back covering the laser beam. This affects the
results. In future I need to be careful about placing the cuvette correctly with
smooth sides front to back.
Using a cuvette:
It is used to sample so it can be placed in a colorimeter to measure absorbance.
Cuvette contains rigid and smooth side. Smooth side is used to place front to back. I
would hold the cuvette from the smooth side which leaves fingerprints affecting the
results because smooth side is used to allow light to pass through to determine the
concentration of a substance affecting the results. The cuvette would also overflow
the cuvette or have spills. This can affect the results. My strength is that I
understand how to read and use the colorimeter. Future improvement for using a
cuvette would be that I should remember to hold the cuvette from the rigid side. If I
accidentally held it from the smooth tissue, I would wipe the cuvette on all sides
with a lens tissue to clear away fingerprints or spills from the sides of the cuvette.
For making sure the cuvette does not overflow I would fill it using it a pipette.
Serial dilution of a copper sulphate:
I am good at preparing a dilution as I can measure and pour things accurately. I
used a pipette to help me. But the beaker went up in 25s which was not bad, but it
could mean that the solution may contain possible errors as it did not contain 100.
So, in future I would like to use a beaker that goes up in 50s.
Calibration curve:
A calibration curve is used to determine the value of an unknown substance. A
graph is used as the result is used to draw a graph which produces a curve. I have
no weaknesses when drawing a graph because I can plot, and label axis. From that
curve you can find out the value of unknown substance. The weakness I had was
that the curve was not drawn properly which it would affect the concentration of the
unknown substance. In future I would use a data logger to produce the graph, so it
is accurate which makes the value accurate of unknown substance.
Skills developed in Calorimetry:
Drawing a graph:
, It is used to represent data. It shows relationships in data, but it can contain errors
which affects the result. Using the graph, I am able to draw a cooling curve. This
helped to calculate rate of cooling. I have no weaknesses when drawing a graph
because I can plot, and label axis. I can also calculate rate of cooling curves.
However, in future a data logger could be used to draw the graph to be sure that
the data is accurate so identifying rate of cooling is much more accurate.
Using a thermometer:
It is used to measure how hot or cold a substance is. The thermometer was used to
measure temperature of stearic acid. I can read the thermometer and know how the
thermometer works. But sometimes, it is hard to read the thermometer as it is in
between the reading (e.g., 24.5). I do not have any weaknesses, but I would try to
learn how to read thermometer accurately.
Digital thermometer:
It is used to measure how hot or cold a substance is. We did not use digital
thermometer but the skills I contain from before are that I can easily take readings
from the thermometer and change the units. This means that I have no weaknesses
so in future I would like to use a digital thermometer instead of mercury
thermometer, so my results are accurate.
Using stearic acid:
Stearic acid is melted and the kept at room temperature so it can return to a solid.
The data is then collected and recorded to produce a cooling curve. I am able to
record data of stearic acid when it melts and freezes. When I used stearic acid, I
forgot to use googles most of the time as they can be a possibly cause damage to
eyes. In future, I would remember to use goggles.
Using a calorimeter:
It is used to measure the heat during a chemical reaction. I can set up the
calorimeter and make sure that everyone is safe. However, when I carried the hot
water, I did not use a tissue. Because the water is extremely hot it would have
possibly burnt my hands. So, in future I would like to use tissue or something to
carry hot water to make sure that I do not burn my hands and spill it anywhere.
Skills developed in Chromatography:
Drawing baseline:
It is used so that it samples of chromatography can be put in straight line. If
samples are added on a straight line, they would not travel at the same point which
would result in having inaccurate results. My weakness is that the line was not
straight. But I redrew the line to make sure I get accurate results. In future, I need
to make sure the line is drawn straight using a ruler.
Micro capillary tube:
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