What exactly are gravimetrics anyway, huh? In general, it's the part of chemistry that involves the ways that you measure things, such as size or weight. In order to measure anything in chemistry, you have to know the basics.
The basic unit of length in chemistry is the centimeter(cm). Although the SI base unit of measurement is the meter, not many things in chemistry are a meter long.
The basic unit of mass in chemistry is the gram(g). In this case, the basic unit is also the SI base unit. The reason for this is that the molecular mass of some compounds is very small, therefore small units of measurement are preferable.
The basic unit of volume in chemistry is either the liter(L) or the milliliter(mL). The milliliter is defined as the volume of a cube of space with sides of one centimeter each.
In addition, the basic unit of temperature is the Kelvin. The increments for the Kelvin scale are the same as the Celsius scale and to convert from one unit to another, you add 273.15:
K - 273.15 = Co
Notice that the K(which stands for Kelvin) does not have a degree sign after it. Why 273.15? Well, the scientist for which this unit of measurement is named after, Kelvin, found that the freezing points of several compounds, when extrapolated from a graph of temperature vs. pressure, converged upon one point. This point, coincidentally enough, was the point where pressure equaled 0. The temperature was -273.15 Co. Since the pressure of any compound cannot be negative, Kelvin named this point as absolute zero. Kelvin then realigned the temperature scale to equal zero at this point, which is why it is known as the Kelvin scale.
Two other units of temperature measurement are Fahrenheit and the Castro.
Fo = 9/5 (Co) + 32
Castro = Co + 75
Precision and Accuracy are simple concepts but are easily confused. Precision deals with being able to repeat an experiment and have the similar results time after time. Accuracy deals with being able to get the experimental result close to the actual result.
Significant figures is a topic that students usually try not to involve in their experiments, but nevertheless is a crucial factor when working with small numbers. Most people use the shorthand term "sig figs" because it is easier to write.
Here are a few rules when dealing with significant figures:
1) Zeroes as placeholders are not significant. e.g. "100"
only has 1 sig fig. It can be expressed as *1 x 102.
2) Any non-zero digit is significant. e.g. "1," "2,"
"3"
3) Zeroes after a non-zero digit are significant. e.g. "100.0"
has 4 sig figs.
4) Zeroes withing a number are significant. e.g. "404 has 3 sig figs.
When multiplying (and dividing), the number with the least significant figures is how many sig figs the answer should have.
When adding (and subtracting), the number with the least digits after the decimal places is the how many decimal places the answer should have.
*This is known as scientific notation. Scientific notation works by being able to show a large or small number without all the zeroes, such as 10000000000 or .000000002. The basic number, "1" in the first case, is multiplied by a power of ten, which would be 1010. On the other hand, when the number is very small, such as the second example, "2" would be multiplied by 10-9. If you need more help, please go ask a math teacher.