Background: In the scientific world, many instruments are useful in the discovery of new and exciting things, but how can we rely on these instruments if they are neither accurate nor precise. Also, how would one go about selecting a tool if they don’t know the accuracy and precision of it? Accuracy and precision are two words that are used interchangeable when in fact they have very unique definitions as follows:
* ACCURACY: the relative closeness a value has to its intended or “true” value.
* PRECISION: the relative closeness of a set of values in relation to each other.
An example would be like a target. If the three arrows all hit the bulls-eye, they would be accurate and precise. If all three missed but were in the same general area, they were precise but not accurate. Also, if all three missed and were far away from each other, they were neither accurate nor precise. To a scientist a perfect instrument is one that is completely accurate and extremely precise.
Safety: Like in every lab done in a science classroom setting and in a professional laboratory, safety here is vital. Following is a list of safety rules to maintain at all times when performing this lab.
1. Always wear goggles to keep chemicals and objects out of the eyes.
2. There is a mixture of water and electrical equipment so be sure not to get water near the electrical plugs or sockets.
3. Treat each instrument with care and use them only as they are to be used.
4. Never fill a pipet with your mouth.
5. Never drink ANY chemicals used in the lab.
Materials: Most labs need materials. Below is a list of items needed for this lab.
* Safety goggles
* Distilled water
* Small beaker for holding water
* Weigh boats
* Carolina brand digital scale
* Denver brand digital scale
* OHAUS brand digital scale
* OHAUS brand triple beam balance
* Micro-pipet (100-1000µL)
* Micro-pipet (20-200µL)
* Micro-pipet (.5-10µL)...