CHEM 130
Exp. 1: Metric Measurements
Introduction
:
There are numerous aspects to chemistry, but a common thread between them all is the process of collecting data and
observations through field studies or in a laboratory. It is critical to understand how to make and read measurements, and we will
focus on the basic types in this experiment: mass, length, volume and temperature.
All quantitative
measurements (involving a numerical value) are meaningless without an associated unit. It is necessary to
always include a unit with a number, and that unit is determined by the measuring device. Since there are many different units for
mass, volume, length, etc., we will look at the relation between some common units from the English system and the metric
system during lab.
The other major goal is to learn how to use, read and interpolate the basic measuring devices found in the laboratory, such as
the Top Loader Balances, Graduated Cylinders, Meter Sticks and Celsius Thermometers. The concept of significant figures will
be covered in depth to aid in understanding the limitations inherent in any measurement and later calculations involving that
value.
Discussion:
There are many basic concepts that will be carried throughout the entire semester in lab which are briefly covered below.
More details will be given as the semester progresses.
1)
Safety
: Safety rules are covered the first day of lab, and a 20 question, multiple choice safety quiz is taken on the second day
of lab. All safety rules must be followed at all times, with specific ones covered in the prelab lecture for each class. Make sure
you are on time! Safety goggles are required by the second day of lab.
2)
Primary/Secondary Data
: Primary data should always be written in ink directly onto your data sheets. These involve both
quantitative measurements and qualitative observations. Think of primary data as anything you must be in the lab in order to
record. Secondary data is always in pencil and involves calculations or questions answered using the Primary data.
3)
Prelab Assignments:
These are due at the beginning of lab, no exceptions. You may not perform the lab if the prelab is not
complete. You can download these from the instructor’s website and have an entire week to ask questions if you are unsure of
anything. Be familiar with the proper instructions and calculations for the lab before you try anything!
4)
Problem Solving and Calculations
: All work must be shown for mathematical calculations, and all unit conversions should
be set up as unit line equations for clarity. Be neat! Always include units for any number.
For example, to calculate the density (D) of a liquid with a measured volume (V) of 9.83 mL and a mass (M) of 12.90 g, show
the formula, insert the primary data with units, show the unrounded answer, and then box the rounded answer to the appropriate
number of significant figures with the correct units.