Section
Title: (1 point Maximum)
(Use the name of the lab)
0 points
No Title/Title is illegible or irrelevant.
1 point
2 points
3 points
Legible Title relevant to the lab
Purpose: (1 point Maximum)
No Purpose section
(What is the reason for this lab? What
Section is illegible
concepts will be explored in the lab? What Section does not cover the lab performed
hypothesis will be tested?)
Legible purpose that answers at least one
of the questions:
• What is the reason for this lab? What
concepts will be explored in the lab?
• What hypothesis will be tested?
*Note: original data should be included but
points will be awarded in the Data
Collection and Safe Lab Practices.
Theory: (2 points Maximum)
• Define of key term(s)
• Explain Key Concept(s)
• Include chemical or mathematical
equations (when applicable)
No Theory Section
Section is illegible
Section does not define key terms, explain
key concepts, include chemical or
mathematical equations (if applicable)
Theory section present and legible
Section includes some but not all of the
following:
• Definitions of key term(s)
• Explanations of Key Concept(s)
• Includes chemical or mathematical
equations (when applicable)
Theory section is present and entirely
legible
Section includes all of the following:
• Definitions of key term(s)
• Explanations of Key Concept(s)
• Includes chemical or mathematical
equations (when applicable)
Calculations/Graphs: (2 points
Maximum)
Show any work needed for calculations
Show any graphs (if needed)
No Calculations/Graph Section
Section is illegible
Section is missing key calculations or
graphs
Calculations/Graphs section is present,
legible, and includes some but not all of
the following:
• Calculations shown (including units)
• If applicable, graphs is shown and
includes title, axis labels, and fit lines (if
needed)
Calculations/Graphs section is present
and entirely legible
Section includes all of the following:
• Calculations shown (including units)
• If applicable, graphs is shown and
includes title, axis labels, and fit lines (if
needed)
Results: (3 points Maximum)
No Results Section
Briefly describe and summarize the results Section is illegible
of the lab
Results section is present and mostly
legible
Section is missing key results
Results section is present and legible
Results section is present and mostly
Sections summarizes and describes some legible
but not all of the results
Sections summarizes and describes all of
the results
Conclusions: (3 points Maximum)
Includes any reference values and their
source
Discusses the accuracy of the results
Discusses the precision of the data
Discusses possible sources of error and
what steps to take in the next experiment
to minimize them
No Conclusions Section
Section is illegible
Conclusions section is present, mostly
legible, but is missing most of the
following:
• Reference values
• Discussion of accuracy
• Discussion of precision
• Discusses possible sources of error
and what steps to take in the next
experiment to minimize them
Conclusions section is present, legible, but
includes some but not all of the following:
• Reference values
• Discussion of accuracy
• Discussion of precision
• Discusses possible sources of error
and what steps to take in the next
experiment to minimize them
Post Lab Questions: (3 points
Maximum)
No Post Lab Questions are answered
Section is illegible
Post Lab Questions are answered but no
work is shown
Questions are answered, work shown, but Questions are answered, work is shown,
some incorrect answers.
and all answers correct
Conclusions section is present, legible,
and includes all of the following:
• Reference values
• Discussion of accuracy
• Discussion of precision
• Discusses possible sources of error
and what steps to take in the next
experiment to minimize them
Density and Treatment of Data
Background
Density is a physical property of matter. What this means is that every pure substance has
a characteristic density at a given temperature. In other words, density can be used to
identify a substance. One is able to determine the density of a substance by determining
its mass and volume. Since density is a temperature dependent parameter, the resulting
density is reported at the temperature at which it was determined.
In this exercise you will accurately determine the volume delivered by a 10-mL volumetric
pipet; that is you will calibrate a 10-mL volumetric pipette. Typically the volume delivered
by a volumetric pipette is etched on the the glass along with the temperarture. However, in
practice one should never assume that the volume contained or even delivered by
volumetric glassware is exactly that which is indicated by the etching on the glass. Proper
calibration avoids the introduction of systematic errors in your measurements. Calibration
is performed by first weighing the mass of water delivered by the pipet. The volume
delivered is obtained by comparing the mass of water to its density. Remember to measure
the temperature of the water so that you use the correct density in your analysis.
It is proper laboratory practice to report the accuracy and precision of ones experimental
data. Accuracy refers to how close a given measurement comes to the true value (i.e. the
Theoretical value). Precision, on the other hand, is a measure of the reproducibility of a
given measurement. That is, when an experiment is repeated, precision tells us how close a
measurement comes to another measurement. Precision is determined by a statistical
method named standard deviation In this experiment you will repeat several measurements
in order to generate data such that you are able to statistically analyze your results. Note
that reporting results without specifying the precision is meaninless since one does not
provide information pertaining to the reproducibility of the experiment. For example,
suppose the density of a given metal was determined to be 8.95 g/mL +0.21 g/mL. The
value, +0.21 g/mL, tells us the precision of the density resported. The precision in the
latter case tells us that the density of the metal is between 9.16 g/mL and 8.74 g/mL. The
lower the standard deviation the better the agreement is between subsequent
measurements.
Name:
1. The density of water at 21.0 °C is 997.9950 kg/mº. Using dimensional analysis
express this density in units of grams per milliliter. Be sure to show your work
throughout. 1 kg = 1000g 1,0 m3= 1000,000 ML
997.0950 kg 1000g
X Х
1.0kg
(
. 1000,ooomL
-
1.00 m) 70.987995/
mL
0.9989/ mL
density at 21.0 °C =
2. Using the data illustrated in the figure below. Determine the density of the metal
cylinder. Be sure to show all your work including proper units throughout. Report
your response with the correct number of significant figures.
close-up view
mL
close-up view
ml
80
80
meniscus
60
70-
70
60
60
60
50
50
50
metal cylinder
30
20
10
metal
cylinder
33.625 g
top loading balance
33.6259
56 mL-52mL
33.6259
4 MLL
=8.5 glme
density of metal cylinder
8 g/mL
2
Experimental Procedure
1. Determining the density of a metal
(a) Obtain a metal slug and record the unknown number in your laboratory notebook.
(b) Use the analytical balance to determine the mass of the dry metal slug.
(c) Half-fill a 50-mL or 100-ml graduated cylinder with tap water and record its volume
to the nearest 0.1 mL.
(d) To avoid splattering tie the metal slug with a nylon string and carefully drop it into
the 50-ml (or 100-mL).
(e) Roll the metal slug around in the graduated cylinder to remove any air bubbles.
(f) Take the difference between the two water levels for the volume of the unknown solid.
(g) Repeat the procedure two more times using the same dry mass of the metal cylinder
recorded before.
2. Calibration of Pipette
(a) Use the analytical balance to weigh a clean and dry 50-mL Erlenmeyer flask with a
stopper. Weigh the flask and stopper to +0.001g. To avoid contamination handle the
flask with a paper towel or crucible tongs.
(b) Pipette 10-mL of deionized water into the weighed flask/stopper.
(c) Weigh the flask and its content to 0.0001 g.
(d) Using the addition method, repeat this procedure two more times. In addition
method, subtract the previous mass reading to obtain the mass of water for each trial.
(e) Determine the temperature of the water to 0.1°C and look up the appropriate density
(the density is found in the CRC Handbook). Record the density and calculate the
volume of water corresponding to one of aliquot of water delivered by the 10-ml
pipet (the term aliquot refers to a sample taken for analysis). Question: Is the
volume of the pipette really 10-mL?
3
Purchase answer to see full
attachment