Laboratory Procedures
A. Determining
Measurements and Data Collection
1. Measuring length: Use the meterstick to
measure the length of the following items in centimeters (cm) with
correct number of significant figures.
Personal measurements are (a) fingernail width, (b)
fingernail length, (c) circumference of wrist, (d) length of shoe, (e)
standing height.
Measure to the nearest 0.1 cm for all length
measurements.
B. Comparing Metric and American Units of Length
1. Using a ruler and a meterstick, determine the number of centimeters (to 0.1 cm) that correspond to a distance of 12.0 inches.
1. Volume of Solid Direct Measurement Obtain
an unknown
solid sample from your instructor.
a) Record the unknown # .
b) Record its shape.
c) Use the meterstick to determine the dimensions
of the solid in
centimeters. Since the equation for determining volume depends on the
shape of the object,
use
the chart below to determine which dimensions
are needed to
determine
the volume of your solid object. For example, if the object is a
cylinder,
only height and diameter are needed.
d) Use the table below to calculate the volume of the solid.
Shape Dimensions Volume (cm3)
cube length (L) V = L3
rectangular length (L), width (W), height (H) V = L x W x H
cylinder diameter (d), height (H) V = (3.14 x d2 x H)/4
2. Volume of a Solid by Volume Displacement When a solid object is submerged under water, it displaces the water by the amount of its own volume. The difference in the water level before and after the object is submerged is equal to the volume of the object submerged.
a) Obtain a 25.0-mL graduated cylinder and fill
it with water until
it is
about half full. Record the volume of the water. Slowly and
carefully slide the object
into the graduated
cylinder, held at approximately a 45o angle to submerge
it. Be careful not to splash any drops of water
on
the sides of the cylinder.
Record the new volume of
the water to the
nearest 0.1 mL.
D. Determining the Mass of Solid
1. Demonstration: Your lab instructor will demonstrate the proper use of the laboratory balance.
2. Mass of Solid: Determine the mass of your solid object using the balance (to the nearest 0.001g). In CHEM 1030 lab all mass determinations will alwaysE. Determining the Density of Solid
Density is defined as mass in grams per unit volume in milliliters or g/mL.
Density of solid = Mass (g) of solid/Volume (mL) of solid
Calculating
the density of the solid: Using
the
mass of the solid that you determined in part D and the volume
of
the solid that you determined in part C (by
displacement),
calculate the density of your solid object.
DATA
TABLE
Please Click on Link
above. Build a similar table in the prelab write up of your Lab
Notebook to Collect Data.
CALCULATIONS:
Show all
calculations in Lab Report underneath the Data Table
1. Area of Rectangle
2. Conversion of cm3
to mL
Questions to be addressed in your conclusion:
F What are some reasons that the resulting values for the area of the rectangle determined in part A might vary from person to person?
F In part B, how does your experimental conversion factor for cm to inches compare to the theoretical value of 2.54 cm/in?
F In part C, how close are the
results
for the volume of the solid from measuring the dimensions to the volume
you
determined
by displacement of water?
F Which method of volume measurement
do you
think is most accurate: direct measurement or measurement by
displacement ? Why?
F After having determined the density
of
a solid, briefly describe stepwise, how you would propose to
experimentally
determine the
density of a liquid.
(updated 1-22-10 P Powers)