_bob _
By: bob
Introduction: The meaning of this experiment was to understand and use the
basic tools for chemistry. During this experiment, many calculations were
taken from data collected. We had to make sure measurements were taken
accurately in order to complete the right equations. Using these equations we
could determine volume, weight, and masses of specific objects. Also, we were
introduced to utilities found in every laboratory. These were used help find
the mass and temperatures of objects. The MeasureNet was used to help us graph
out data and take temperatures while we used different balances to record
masses of objects. Procedure: The procedure followed was that given in the
Lab booklet Data and Results: The data has been organized by using different
tables and graphs. Multiple trials were performed in order to determine
accuracy. Refer to the report sheets for data information. All graphs and
tables are included also. A.) The graph of Water Temperature vs. Time was
included. B.) Graphs that were used have been given for the experiments and
also the lab report sheets summarize the experimental results that were
recorded in the labs. Glassware Used Expected Actual Volume Volume
Beaker 50 ml 51.062mL Graduated Cylinder 50ml 48.841mL Trial2
Pipet 10ml 9.809mL 9.804mL Buret 10ml 10.064mL 10.060mL Discussion:
Accuracy is defined as the quality or state of being accurate or exact when
recording measurements in the experiments. Precision is being precise in a
measurement or an operation of the experimental stateIn the mass
measurements part of the lab we learned how to use the scale and found that
these scales are very exact. They had very miniscule difference between the
trials and between the measured and calculated masses of the crucible parts.
On the Water Temperature vs. Time graph the temperature increases abruptly
when heat is applied to the water causing it to boil. When it reaches boiling
point heat was taken away and the temperature decreases slowly and the graph
ends at 900 seconds Through the experiments we learned that the beaker is
the most unreliable tool to use. Although it measures to a certain point the
wide diameter could cause the results to be inaccurate, therefore throwing off
the equations and corrupting the experiment. The graduated cylinder is the
next least accurate. It holds many of the problems that the beaker has like
the diameter and lack of precision. The two most precise instruments would be
the pipet and buret since their diameter is small and it records closer to the
actual measurement 1. A.) In the experiment the temperature rises
drastically in the first 250 seconds Then it stays flat till about 250
seconds and then slowly decreases. B.) The temperature increases as the water
of the heat starts to hit the boiling point. The boiling point of this part of
the experiment is 100 degrees Celsius. The temperature then decreases to it
normal state. 2. The sensitivity the balance can detect is 0.0001g. 3. The
largest difference between two of my measurements using the analytical scale
was .0008. 4. The error statement we found for the beaker was 4.91mL. The
graduated cylinder was .027ml. The pipet was .01 ml and the buret was 2.164mL.
5. Using the Histograms from the class we came to the assumption that the
buret is the most accurate tool for measurement. The class results for the
buret was 10.007 mL. The second most accurate tool was the pipet and its
volume is9.883 mL. The cylinder followed next with a 49.352 volume. The least
accurate was the beaker, its volume was 46.785 mL and this was caused by the
wide diameter. The relative error of the beaker was 2.08%, while the error for
the cylinder was 2..37%. The error for the pipet was .19% for both trials and
the burets errors were 0.63% and 0.60% according to the results. 6. A.) The
standard deviation shows us that the beaker was least accurate with a 1.758
error. The cylinder had a 0.680 error and was second least accurate, but was
more precise than the beaker because studying the Histograms results shows us
that the error was present for the rest of the class. The reason for this
would be from the wide diameter of the beaker. B.)The buret and pipet were the
closest in standard deviation. The buret had a 0.144 error while the pipet had
a .120 error. This shows how accurate the pipet was during the
experimentation. If procedures were accurately taken using the pipet then
measurements would be more precise than the buret. One of the problems the
pipet had was using the pipet pump. The pump made it difficult to draw water
out of the beaker and this could affect the results of the experiment. 7. This
would affect the results of the experiment because carbon tetrachloride could
be a thicker substance and would be hard to use the pipet with since the
diameter of the pipet is so small. 8. A.) A buret would be most accurate for
measuring ten mL of a liquid with a 3% accuracy. B.) A graduated cylinder
would be most accurate for measuring fifty mL liquid with a .5% accuracy. C.)
A beaker would be most accurate for measuring several twenty mL samples of a
liquid with a precision of 10%. Conclusion: In this lab we were able to
achieve most of our goals. The goals were to learn how to use the equipment
and to see what devices are the most accurate for measurement of volume and
mass. The errors in this lab seem to pop up everywhere. The first was that the
measure net system did not work to find temperature for the probe calibration.
The next was that 1 of the analytical balances would not rezero. Most of the
errors dealing with finding volume came from human error by not taking the
correct measurements. These thing contributed to the error and standard
deviation in this Lab.
Word Count: 988
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