We introduced the seven Base SI units: mass, length, time, temperature, amount of substance, electric current and luminous intensity. In CHEM 1314 we are interested in the first five of these base units; mass, length, time, temperature, amount of substance. You must know these usints and their symbols.
We then discussed the derived units important to our class this semester; volume, area, temperature (degrees Celsius), temperature (degrees Fahrenheit), heat, pressure and density. Again you are responsible for these units and their symbols.
Everyone is responsible for memorizing the prefixes used with the metric units. The most important are giga, mega, kilo, centi, milli, micro, nano, pico and femto.
Everyone is also responsible for the following English relationships;
12 in = 1 foot
3 feet = 1 yard
5280 ft = 1 mile
4 quarts = 1 gallon
2 pints = 1 quart
16 ounces = 1 pound
2000 lbs = 1 ton
We looked at an animation to explain the difference between precision and accuracy.
Accuracy means the the agreement of a particular value with the true value.
Precision is the agreement between several measurments of the same quantity.
We looked at an animation demonstrating the relationship between measurement and significant figures.
We listed the rules for assigning significant figures and did several examples. Then we started to discuss how to handle significant figures when doing calculations. Because the browser crashed I was not able to show a few 'simple' examples of how to determine the correct number of significant figures in calculations. So I made an example up off the top of my head. It turned out to be more challenging than I had planned. I apologize for that.
Here is the problem we did at the end of class. Look it over and we'll review a few more examples on Monday.