Experiment 1
Introduction to Some Laboratory Measurements
Introduction
In this experiment you will familiarize yourself with the English & metric system of measurement,
weigh with a centigram balance, and study the operation of a laboratory burner. Volume will be measured
directly with a volumetric device such as a graduated cylinder or calculated from dimensions if measuring a
regular geometric shape such as a cylinder or rectangular bar. Density is found by dividing mass by
volume. In this experiment, the density of water is determined.
Procedure
Part 1: Metric to English system of measurement using a ruler.
Using either a meter stick or a centimeter ruler, measure the length and width of this page to the
nearest 0.1 mm. After taking the measurements, convert all lengths to the specified units on the report
sheet. Be sure to show all your work for the conversions.
Next determine the volumes of test tubes by two different methods. In method one, use the cm ruler to
measure inside diameters and lengths of two different test tubes to the
appropriate degree of precision. (When measuring the height (h)
of the inside of the tube, measure to where you think the curvature
begins near the bottom of the tube.) If all your test tubes are the same,
borrow one of a different size.
Do not include the thickness of the glass in the reading.
Now calculate the volume of each test tube using the formula: V = r2h keeping in mind  = 3.14, r (the
radius) = ½ the diameter. Round off your final calculation to the appropriate number of significant figures.
Method two, measure the volumes of the same two test tubes, by filling them with water and pouring
the water into a 25 or 50 mL graduated cylinder. Read the volume on the cylinder by estimating to the
nearest 0.1 mL. What did you observe about the volume collected via the two different methods?
Part II: Weighing objects using the balance.
Your instructor will explain the operation of the balance you will use in your laboratory work. Weigh
a clean dry 100 or 150-mL beaker to 2 decimal places using the centigram balance. Return to your
workstation and measure out 25.0 mL of tap water using your graduated cylinder. Read the volume in the
cylinder to the nearest 0.1 mL Pour that water into the pre-weighed beaker. Now re-weigh the beaker
containing the water. Do not spill water on the pan! Record your measurements, both volume and
associated weight, in your lab note book with the correct number of significant figures and correct units.
Repeat the same steps for 35 or 45 mL of tap water. It does not matter how much water you use, it ONLY
matters if you record the actual volume. Technique Alert! For precision remember to use the same balance
for all your weighing’s. There is a direct relationship between an object’ mass and volume called density.
Using the formula d=m/V, where m stands for mass measured in grams and V stands for volume measured
in milliliters, calculate the density of water for each of your trials. What did you discover? What do you
Los Angeles City College
Chemistry 60
believe would happen if you measured out 15 mL of water, weighed it, and repeated the same calculations?
Be sure to show all work for the conversions.
Look up the accepted value for the density of water at a room temperature of 20oC. (You can check
the CRC Handbook for the value at 20oC or use the internet). Report the value to three significant figures.
Calculate the % error in your value for the density of water. The general formula for calculating a percent
error is:
% error =
[ experimental value – accepted value ] x 100
accepted value
Keep the + or – sign in the answer. It indicates whether your result is high or low.
Part III. Temperature: The Thermometer & the Bunsen Burner.
The "Bunsen" burner is commonly used for laboratory heating operations. Introduce yourself first to
the Bunsen burner. There are several types of burners, differing from each other in details of construction,
but each has a gas inlet, gas control knob, a tube for mixing air and gas, and an opening near the base of the
tube for introduction of air. Find these parts on your burner and make a neat labeled sketch of the burner.
Light the burner by partially closing the air vent, turning on the gas part way, and bringing a match in
toward the top of the burner from the side, touching the top of the tube. Close the air hole at the base of the
tube. This kind of flame is called a “luminous flame”. Take a long copper wire and place the tip of the
wire in the “luminous flame”, take note of your observations in your lab notebook. Next, open the air hole
about half way and adjust the flame with the gas until the flame is about 8 to 10 cm high and the flame is
blue. Take the same copper wire and place it in the blue flame and once again, record your observations in
your lab notebook. Lastly, adjust the air intake such that the flame exhibits two blue tones, an inner light
blue flame and an outer darker blue flame. Place your copper wire in several areas of the flame and record
your observations. A blue flame is hotter than an orange flame.
Now it is time to use the Bunsen burner. Set up a ring stand with a ring clamp & wire gauze. Fill a
250 mL beaker half way with tap water and two boiling stones. Place the beaker of water on the wire
gauze and set up the Bunsen burner next to the ring stand. Measure the Temperature of the room
temperature water to the nearest 0.1oC. Relight the Bunsen burner. If you are to boil water, which type of
flame should you use? Place the lit Bunsen burner under the wire gauze holding the beaker of water. Heat
the water to boiling. After 5 minutes of full boiling, measure the temperature of the water. Record that
measurement in your lab notebook. Remove the thermometer and wait another 5 minute before remeasuring the temperature of the boiling water. Record that value. Repeat after another 5 minutes have
past. Look up the boiling point of water. This technique is referred to as “calibration of the thermometer”.
Is your thermometer accurate? The boiling point of any pure substance is characteristic of that material
and can be used to identify that substance.
Los Angeles City College
Chemistry 60
Experiment 1
Name _____________________
Introduction to Some Laboratory Manipulations
Data and Report Show all calculations on this report sheet.
Part I.
A. Length of page: ______________cm _______________mm
(show calculations in space below)
Width of page: ________________ cm
(show calculations in space below)
_______________mm
Data using the ruler: (show units)
Test tube #
diameter (d)
_______________km
_________________in
________________km
_________________in
height (h)
volume (cm3)
Volume (L)
1.
_________
__________
___________
___________
2.
_________
__________
___________
___________
Show the set-up of one volume calculation.
Data using the graduated cylinder (show units)
test tube #1 :
volume ____________
test tube # 2:
volume: _____________
What can you conclude about the two different methods for measuring volume? Which method, the measurement of dimensions,
or the measurements of volume with a graduated cylinder, do you think gives a better result? Explain why. (recall the
assumption about measuring the test tube as a cylindrical object).
Los Angeles City College
Chemistry 60
Part II.
Volume of water
________________mL
________________mL
Weight of beaker and water
__________________g
__________________g
Weight of beaker
__________________g
__________________g
Weight of water
__________________g
__________________g
Room Temperature of water
_________________oC
_________________oC
Density of water (calculated)
________________g/mL
________________g/mL
Density of water from resource book
________________g/mL
________________g/mL
% error in density
________________
________________
Show setup of calculations of density and % error for one trial:
Part III
Sketch of burner (Label parts):
What color is the flame when the oxygen intake has been minimized? ________________________
Describe below what you observe when you placed the copper wire in the three different flames.
What color is the hottest flame?_________________
Use the CRC handbook or other resource material to look up the melting point of copper and record that value here:
__________________. What can you conclude about the actual temperature of the hottest flame?
Los Angeles City College
Chemistry 60
Temperature Manipulations
__________________oC
Room Temperature of water
Temperature of boiling water
_____________oC
Theoretical temperature of boiling water from handbook
Is your thermometer accurate?
_____________oC
_____________oC
__________________oC
_________________
Questions
1. An empty graduated cylinder weighs 79.35 g.
35
It was filled to the extent shown in this partial segment
of a graduated cylinder with a liquid called carbon
tetrachloride (CCl4). The density of CCl4 is 1.61 g/mL
How many grams does the cylinder weigh together with
the CCl4?
25
2. a) Look at the densities of the elements on the periodic chart given in the introduction to measurements section of this lab
manual, (online). What general trend, an increase or decrease in density, do you see as you look from the top to bottom in a
given group (vertical column of elements, for example Li to Fr)?
b) What general trend do you see in the densities of elements on the left half of the periodic table, as you read from left to right
(for example from K to Cr) ?
3. a) What is the densest element?
_________
(refer to the density table in the introduction to measurements)
b) If you have a coin made of this element that weighs 100.0 g, and has a thickness of 4.00 mm, what would the diameter of the
coin be, in cm ? (V = r2h h = 4.00 mm)
4. 12 karat gold contains 50% gold and 50% copper. What do you think the density of 12 K gold should be (Hint, look up the
densities of pure copper and pure gold.)
Los Angeles City College
Chemistry 60