CHM 101 American University of Sharjah The Use of Volumetric Glassware Lab Report i need help in pre and post laboratory questions in the lab report.you wi

CHM 101 American University of Sharjah The Use of Volumetric Glassware Lab Report i need help in pre and post laboratory questions in the lab report.you will find it when you scroll down in the pdf file.you will find pre laboratory questions at page 7/10 and the post laboratory questions at page 10/10.i want it hand written. EXPERIMENT 1: THE USE OF VOLUMETRIC GLASSWARE
Objectives: (1) To practice making volumetric measurements using common laboratory glassware. (2) To
become familiar with the basic equipment found in a general chemistry laboratory. Note: Your instructor will
demonstrate how to properly use the lab equipment in this experiment.
I. Volumetric Glassware
A. Graduated Cylinder
A graduated cylinder is widely used to measure the volume of a liquid. It is
available in various sizes and made of different materials, such as glass or plastic. By
using the scale on the cylinder wall, one can easily obtain a clear measurement that is
precise enough for many applications.
Whenever a liquid is contained in a narrow glass container; a
meniscus forms. This curved surface is caused by the molecules in the liquid
interacting with the molecules of the container wall. To correctly measure the volume in
any narrow glass container such as a graduated cylinder, first place it on a flat surface.
Then, carefully read the bottom of the meniscus at eye level. Additionally, to ensure an
accurate measurement, place a piece of white paper behind the glass container to view
the meniscus clearly.
B. Beaker
A beaker is a specialized piece of glassware designed to contain and easily pour
reagent chemicals. In the laboratory, a Pyrex beaker is often the piece of equipment
chosen to heat liquids. The scale on the side of a beaker wall is not very precise,
therefore; it is generally used to make approximate volume measurements.
C. Buret
A buret is a very tall glass tube with marked graduations in 0.1 mL increments that
allow for precise volume readings to the nearest 0.01 mL. It is designed to deliver
variable, yet precise volume measurements of liquid and is fitted with a stopcock at its
base. The buret is securely held in place using a special clamp that is attached to a ring
stand.
The buret should be cleaned carefully using soap, water and a special buret brush. Once clean, a
buret is rinsed with tap water and filled with distilled water. Before using the buret in an
experiment, a student should first drain the distilled water, then rinse it a few times with small
portions of the solution of interest (discard the rinsings in the correct waste container). After
using, the buret should be rinsed and then filled with distilled water.
To fill a buret, first place the top below eye level and always use a funnel. Once filled, remove the funnel,
make sure there are no air bubbles in the buret tip, and check for leaks in the stopcock before beginning
the experiment. The scale on a buret is opposite of all other volumetric glassware, and is read from top
to bottom. Like the graduated cylinder, it is important to read the bottom of the meniscus that forms by
the liquid in the buret at eye level. To find the volume of reagent solution used, first record an initial
volume level. Next, record the final volume level after the correct amount of reagent solution has been
dispensed. The difference between the two volume measurements (Vfinal – Vinitial) is the volume of the
reagent that has been used in the experiment.
D. Pipet
A pipet is a long, thin glass tube made to contain and to deliver an exact volume of liquid from one container to
another. It is a delicate piece of volumetric equipment and should be handled with care. There are many types
of pipets, but two are most commonly used in general laboratory work. The first is a volumetric pipet which
has a single mark etched on it and is used to transfer only one specific volume of liquid. Secondly, a Mohr pipet
has multiple graduation marks making it useful for delivering a range of volumes.
Before using a pipet, be sure it is clean and without defect. To ensure accurate volume measurements, first
rinse the pipet with distilled water, and then rinse it a few times with the solution that will be used in the
experiment (discard the rinsings in the correct waste container).
Remember these important points before using a pipet:






Never pipet a chemical directly from a reagent bottle.
The pipet tip must be clear and without any cracks. Always keep the pipet in a vertical position while in
use.
Never use your mouth to fill a pipet. Always use a pipet bulb or pump for this purpose.
Do not force the bulb or pump onto the mouth of a pipet.
Do not allow the liquid to enter the bulb/pump.
Do not attempt to fill the pipet by running water from the tap directly into the mouth of the pipet.
Pipetting involves two major steps. (1) Draw the solution into the pipet to the correct level needed and make
sure it remains there. (2) Allow the solution to drain from the pipet into a designated container in a controlled
manner.
A pipet pump is a mechanical safety device designed to supply the suction needed to draw liquid chemicals into
the pipet. Two types of pipet pumps are commonly used:
(1) 3-Way Rubber Safety Bulb. In a rubber safety bulb, the liquid flow is controlled
by three valves marked A, S, and E which stand for aspiration, suction, and emptying,
respectively. To use, squeeze valve A on the bulb while squeezing the large bulb itself to expel
air from it. Place the rubber safety bulb over the top of the pipet, being careful not to force it
on or push it too far down. Insert the pipet tip below the surface of the solution, squeeze
valve S to allow the liquid to be drawn up into the pipet. Stop squeezing the S valve when the
solution is a little higher than the desired volume. Squeeze the E valve to adjust the liquid
level to the correct calibration mark on the pipet and/or to empty the contents of the pipet
into the correct container.
(2) Pipet Pump. A pipet pump works like a syringe in which the liquid suction is controlled by using
your thumb to rotate the piston wheel. It is very easy to operate using only one hand. By rotating the piston
wheel up or down, the liquid is either drawn into or out of the pipet, allowing for exact volumes to be measured
with ease. Finally, to dispense the liquid from the pipet, press the release lever on the side of the pump.
Here are some important techniques that should be put into practice while working in the laboratory:



Make sure there is enough solution inside the beaker/container to completely fill the pipet.
Always touch the inside of the beaker with the tip of the pipet to remove the last drop of liquid hanging
from its tip.
While filling a pipet, always keep the pipet’s tip is below the surface of the liquid at all times.
Otherwise, air will rush into the pipet which in turn may cause liquid to flow into the pipet bulb/pump;
thereby damaging or destroying it.
II. Other Useful Lab Equipment and Techniques
A funnel is used to help transfer liquids and some solid chemicals (very fine powders) from one
container to another. It is conical shaped with a long stem and is available in glass or plastic. In this
experiment, a funnel will be used when filling a buret.
A wash bottle is a squeeze bottle with a nozzle, that is sealed with a screw-top lid. When the bottle is
squeezed, the liquid inside becomes pressurized and is forced out of the nozzle via a narrow stream
of liquid. Wash bottles are usually filled with water or a solvent, and used to rinse various pieces of
laboratory glassware.
A digital electronic balance is an important piece of laboratory equipment that is
capable of giving precise mass measurements. (Recall that mass is a measure of the
amount of matter in a sample of some substance.) Some advanced models may have
a chamber above the balance pan to block air flow. When an object is placed on the
pan of the balance, it directly gives a digital readout of its mass in grams.
Before using a balance, remember the following:





The electronic balance is a delicate, expensive instrument that should be treated with care. Always
treat it with respect and keep it clean & dry.
Never place any chemicals (solid or liquid) directly on the pan of the balance. In addition, before
placing glassware or any container on the pan of the balance, always make sure the bottom of the
container is clean and dry of any chemicals or water. Chemicals can react with the pan of the balance
and corrode it.
Gently and carefully place the object in the middle of the balance pan.
Clean up any accidental spills immediately from the balance area using a brush or soft tissue. If
necessary, ask your lab instructor for assistance with cleaning up spills.
Never measure the mass of a hot object. The heat from the object can damage the balance and its
electronic circuits. Hot objects can also cause the air around them to become heated. Warm air rises
and the balance may detect this motion, making the digital mass readout less than the actual mass of
the object.
To use an electronic balance, first calibrate the balance before taking a measurement to obtain accurate results.
To do this, press the ‘Tare’ button on the balance and make sure it reads “0” before use. Once the balance is
calibrated, place the object gently in the middle of the pan, wait several seconds for a stable reading, and record
the mass that appears on the screen.
In the laboratory, two methods are frequently used for mass determinations:
Direct Mass Measurement. This is the simplest type of measurement in which the object is placed directly on
the balance pan. The mass of the object is directly recorded from the readout given by the balance. This
method is sufficient for most general laboratory experiments.
Mass by Difference. This method becomes important when more accurate mass determinations are needed in
an experiment. To find the ‘mass by difference’ of a substance, the mass of the empty container is subtracted
from the combined mass of the container and the substance. This method helps eliminate any calibration
and/or systematic errors associated with the balance.
III. Experiment Details
Experiment Overview & Calculations:
Part I. Measuring the Volume of Liquids
Three graduated cylinders, beakers, and/or burets of varying capacities will each be filled with a colored liquid
and displayed in the lab. The volume of liquid will be read by observing the meniscus at eye level and recorded
to the correct level of precision of each piece of volumetric glassware.
Part II. Comparing the Precision of Volumetric Glassware
In this experiment, the volume of a certain quantity of water will be measured (observed volume, Vobs) using a
graduated cylinder, beaker, buret, and pipet. The mass (m) of water that is transferred to each container will
be determined in each case.
The theoretical volume (Vtheor) of water transferred will be calculated using the density (D) of water at room
temperature.
(Equation 1.1)
Room temperature is the ambient air temperature in a particular environment that is being used for a given
procedure. It typically falls between 20-25°C. For the purpose of this experiment, we will consider that the
room temperature in the chemistry laboratory is 24.0C.
Table 1.1 Density of Water at Room Temperature
Temperature of Water Sample
24.0C
Density of water at 24.0C
0.99732 g/mL
The absolute value of the difference between the theoretical volume and the observed volume gives the error
in the measured volume, V, for that particular piece of volumetric glassware.
(Equation 1.2)
For each piece of volumetric glassware, the percentage error (% Error) in the volume will be calculated as
follows:
(Equation 1.3)
The instrument with the smallest percentage error in the volume will be considered the most precise in making
volumetric measurements.
Experiment Procedure:
Record all data and observations directly in your lab notebook in ink!
Part I. Measuring the Volume of Liquids
1. Locate the display of three pieces of volumetric glassware filled with colored liquid. Examine the first
volumetric measuring device, paying attention to the marked scale divisions on it.
2. Record the name of the volumetric glassware, the color of the liquid, and the volume to the correct number
of significant figures that correspond to the precision of the device in the table provided on the lab report
sheet.
3. Repeat steps #1-2 for the other two pieces of volumetric glassware on display in the lab.
Part II. Comparing the Precision of Volumetric Glassware
A. The Graduated Cylinder
1. Obtain an empty, dry graduated cylinder. Find and record its mass.
2. Add about 10 mL of distilled water to the graduated cylinder and record the observed volume.
3. Find and record the combined mass of the graduated cylinder and water sample. Next, calculate the
mass of water in the graduated cylinder.
4. From the mass of water in the graduated cylinder and the density of water given in Table 1.1,
calculate the theoretical volume of water in the cylinder using Equation 1.1.
5. Calculate the error in the volume and the % error in the volume using Equations 1.2 & 1.3,
respectively.
6. Repeat steps #1-5 for Trial 2.
7. Calculate and record the average % error in the volume for the graduated cylinder.
B. The Beaker
1. Obtain an empty, dry beaker. Find and record its mass.
2. Add distilled water to one of the graduation marks on the beaker and record the observed volume.
3. Find and record the combined mass of the beaker and water sample. Next, calculate the mass of
water in the beaker.
4. From the mass of water in the beaker and the density of water given in Table 1.1, calculate the
theoretical volume of water in the beaker using Equation 1.1.
5. Calculate the error in the volume and the % error in the volume using Equations 1.2 & 1.3,
respectively.
6. Repeat steps #1-5 for Trial 2.
7. Calculate and record the average % error in the volume for the beaker.
C. The Buret
1. Obtain an empty, dry beaker. Find and record its mass.
2. Clean and properly fill a buret with distilled water. Record the initial volume reading from the buret.
3. Drain about 10 mL of distilled water from the buret into the beaker.
4. Record the final volume reading from the buret. Calculate the volume of distilled water in the beaker
from the initial and final readings taken from the buret.
5. Find and record the combined mass of the beaker and water sample. Next, calculate the mass of
water in the beaker.
4. From the mass of water in the beaker and the density of water given in Table 1.1, calculate the
theoretical volume of water in the beaker using Equation 1.1.
5. Calculate the error in the volume and the % error in the volume using Equations 1.2 & 1.3,
respectively.
6. Repeat steps #1-5 for Trial 2.
7. Calculate and record the average % error in the volume for the buret.
C. The Pipet
1. Obtain an empty, dry beaker. Find and record its mass.
2. Using a pipet, transfer 10 mL of distilled water to the beaker. Record the observed volume.
3. Find and record the combined mass of the beaker and water sample. Next, calculate the mass of
water in the beaker.
4. From the mass of water in the beaker and the density of water given in Table 1.1, calculate the
theoretical volume of water in the beaker using Equation 1.1.
5. Calculate the error in the volume and the % error in the volume using Equations 1.2 & 1.3,
respectively.
6. Repeat steps #1-5 for Trial 2.
7. Calculate and record the average % error in the volume for the pipet.
EXPERIMENT 1: THE USE OF VOLUMETRIC GLASSWARE
PRE-LABORATORY QUESTIONS
1. What precautions must be taken when measuring the mass of an object using an electronic
balance?
2. Explain why chemicalsa and hot objectsb should not be measured directly on the electronic
balance?
a.)
b.)
3. What is a meniscus? Explain how to properly read a meniscus in a graduated cylinder.
4. The mass of a dry, 50 mL beaker is 49.234 g. The observed volume of water in a graduated
cylinder is 10.0 mL. This water is transferred to the beaker and the combined mass of the water
and beaker is found to be 59.122 g. Given that the density of water at 24C is 0.99732 g/mL,
calculate:
a.) The mass of water
b.) The actual volume of water in the beaker
c.) Percent error in the volume measurement
5. What personal safety precautions must one take before beginning any experiment?
a.)
b.)
c.)
EXPERIMENT 1: THE USE OF VOLUMETRIC GLASSWARE
LAB REPORT
Name: ______________________________________
Date: _________________ Lab Instructor: _______________
AUS ID#: @___________
Lab Section: ______
Part I. Measuring the Volume of Liquids
Name of the volumetric
glassware
Volume
Name of the volumetric
glassware
1.
4.
2.
5.
3.
6.
Part II. Comparing the Precision of Volumetric Glassware
A. The Graduated Cylinder
1 Mass of empty, dry graduated cylinder
2 Observed volume of water in the graduated cylinder
3 Combined mass of graduated cylinder and water
4 Mass of water in the graduated cylinder
5 Calculated volume of water in the graduated cylinder
6
Difference between observed volume and calculated volume
(error in measured volume)
7 Percent Error in volume
Volume
B. The Beaker
1 Mass of empty, dry beaker
2 Observed volume of water in the beaker
3 Combined mass of beaker and water
4 Mass of water in the beaker
5 Calculated volume of water in the beaker
6
Difference between observed volume and calculated volume
(error in measured volume)
7 Percent Error in volume
C. The Pipet
1 Mass of empty, dry beaker
2 Observed volume of water transferred by the pipet
3 Combined mass of beaker and water transferred by the pipet
4 Mass of water transferred by the pipet
5 Calculated volume of water transferred by the pipet
6
Difference between observed volume and calculated volume
(error in measured volume)
7 Percent Error in volume
C. The Buret
1 Mass of empty, dry beaker
2 Initial water level in the buret
3 Final water level in the buret
4 Volume (observed) of water dispensed from the buret
5 Combined mass of beaker and water dispensed from the buret
6 Mass of water dispensed from the buret
7 Calculated volume of water dispensed from the buret
8
Difference between observed volume and calculated volume
(error in measured volume)
9 Percent Error in volume
Part III. Post-Laboratory Questions
1. Which volumetric measuring device should be used when extremely precise
measurements are needed? Explain your choice.
2. Using your results, list the glassware used in this experiment in order of their
level of precision (i.e. most precise  least precise).

Purchase answer to see full
attachment