3.1. The International System of Units http://www.ck12.org
◦C=K− 273. 15
K= ◦C+ 273. 15
FIGURE 3.5
A comparison of the Kelvin (left) and Celsius (right) temperature scales.
The two scales differ from one another by 273.15 degrees.Energyis defined as the capacity to do work or to produce heat. As discussed previously, kinetic energy is one
type of energy and is associated with motion. Another frequently encountered form of energy is potential energy,
which is a type of energy that is stored in matter. Thejoule (J)is the SI unit of energyand is named after English
physicist James Prescott Joule (1818-1889). In terms of SI base units, a joule is equal to a kilogram times a meter
squared divided by a second squared (kg•m^2 /s^2 ). A common non-SI unit of energy that is often used is the calorie
(cal), which is equal to 4.184 J.
Lesson Summary
- Measurements are critical to any field of science and must consist of a quantity and an appropriate unit. The
International System of Units consists of seven base units. - The metric system utilizes prefixes and powers of 10 to make conversions between units easy.
- Length (m), mass (kg), temperature (K), time (s), and amount (mol) are the base units that are most frequently
used in chemistry. Quantities such as volume and energy can be derived from combinations of the base units.
Lesson Review Questions
Reviewing Concepts
- Give the SI base unit of measurement for each of the following quantities.