Lab 1: Measurements in Chemistry
Introduction
Most chemistry lab activities involve the use of various measuring instruments. The three variables
you will measure most are mass, volume and temperature. Failure to obtain a satisfactory result in a
lab is usually the result of improper or inaccurate use of measuring instruments. During this
laboratory assignment, you will become familiar with the measuring instruments most often used in
chemistry.
Equipment:
Materials:
Triple Beam/Electric Balance
100 mL graduated cylinder
10 mL graduated cylinder
400 mL beaker
250 mL beaker
100 mL beaker
Stirring rod
Thermometer
Crucible Tongs
Lab Quest 2
Temperature Probe
Ice
Tap Water
Distilled water
Weighing Dish/Boat
Tums
1. Graduated Cylinders - Volume
a. Obtain two graduated cylinders: 100 mL and 10 mL. Diagram each cylinder with each
diagram clearly showing the volumetric increments on each. What is the smallest volume
increment marked on each cylinder?
b. Half fill each cylinder with water. Notice the shape of the surface of the water. To your
sketches above, draw the shape of the water surface. This is called the meniscus. Always read
the level of the liquid at the bottom of the meniscus.
c. Write down the measurement of the liquid you have placed in each cylinder. Remember to
estimate the last digit (if cylinder reads to nearest 1 mL, estimate tenths place, if it reads to
nearest tenths place, estimate nearest hundredths place).
2. Triple Beam Balance - Mass
a. Place three items (pen, coin etc.) one at a time on the TB balance and record the mass of each.
Estimate to nearest hundredths place. (0.01g)
-
Then measure using the EB electronic balance, record your measurements?
b. Weigh one Tums tablet. Record your data in the data table (estimate to nearest 0.01g). Read
the label on the Tums bottle and record the mass of the active ingredients (calcium carbonate)
in each tablet.
c. What is the mass of the Tums tablet in mg? Show your work on your lab form.
d. Calculate the percentage (by mass) of active ingredient in each of the tablets. Show your
work on your lab form.
3. Beaker - Volume
a. Obtain a 400 mL, 250 mL and 100 mL. How far do the markings on each instrument go?
b. Place 100 mL of water in the 400 mL beaker using the markings on the beaker as your guide.
Pour the water into a 100 mL graduated cylinder (if the water appears to be more than 100
mL, stop at 100 mL, pour out the water and determine the remaining amount of water with the
graduated cylinder. Add additional volume to 100 mL to obtain total volume). Record the
volume. Repeat this with the 250 mL and 100 mL beakers.
c. Calculate the percent error for each of the beakers. Check in Chapter 3 pg 65 for the formula
for percent error. Assume the volume in the graduated cylinder is the accepted volume.
d. What does the percent error tell you about the accuracy of the markings on a beaker?
4. Thermometer - Temperature
a. Record all temperatures to the nearest 0.1 ºC. This means that you will estimate your
measurements to the tenths place (0.1 ºC).
b. Fill your 250 mL beaker full of tap water from the sink. Place your thermometer in the beaker and
once the temperature stabilizes, record the temperature.
c. Fill your largest beaker almost to the top with ice and add distilled water. Stir gently with the
stirring rod for a while, and record the lowest temperature obtained (with thermometer bulb in middle
of the mixture)
d. Together with your partner, get the mass of approximately 10 grams of sodium chloride. To do
this, obtain the mass of the weighing boat and record the mass. Then add about 10 g of sodium
chloride and record the mass again. The difference in the two masses is the mass of the sodium
chloride. This procedure is called “weighing by difference”. Don’t forget your units!
e. Now add the sodium chloride to the ice-water mixture, stir gently with a stirring rod for several
minutes until the sodium chloride dissolves, then read and record the lowest temperature observed.
My Name:
Date:
Hour:
Partner’s Name:
Measurement in Chemistry
Report sheet
Data
1. Graduated Cylinder
a. &
b.
Diagrams:
Smallest volume increment: 100 mL ____________________ 10 mL _____________
c. Measurement of each liquid volume: 100 mL ____________ 10 mL ____________
2. Triple Beam Balance - mass
a.
Item
1
2
3
Mass (g) TB
Mass (g) EB
b. & c.
Tablet
Mass of tablet (g)
Mass of active ingredient
(mg)
Tums
d. [ Percent = mass of active ingredient x 100 ]
total mass of tablet
3. Beaker - volume
a. How far do the markings on each instrument go: 400 mL _____ 250 mL_____ 100 mL ____
b. The actual volume of 100 mL of water in: 400 mL ______ 250 mL _______ 100 mL _______
c. Percent error for each beaker: 400 mL _________ 250 mL ________ 100 mL __________
d. How accurate are the markings on the beaker?
4. Thermometer
Temp (ºC)
Tap water
Ice water
Ice water + salt
Mass of weighing boat + sodium chloride
Mass of weighing boat
Mass of sodium chloride
Conclusion:
1. If you were asked to measure exactly 100.0 mL of water what instrument would you use?
2. If you were asked to measure about 200 mL of water what instrument would you use?
3. Why should you use the same balance for an entire lab activity?
4. Why should chemicals never be weighed directly on the pan of the balance?
5. Explain, step by step, how 5.0 g of a dry chemical should be massed on a balance.
6. Explain, step by step, how 5.0 g of a liquid chemical solution should be massed on a balance.