Why must balances be calibrated to the altitude they’re being used in?
Because gravity changes with altitude.
Calibrate for proper weights
What causes inaccuracy or imprecision in electric balances?
- ferromagnetic samples
- dust lodged between permanent magnet and electromagnet
- temperature
What are the 3 equations that contain % error?
% error = error of measurement/qty desired
% error = SR/qty desired
LWQ = SR/% error
What is trituration?
- reducing particle size by grinding in a mortar and pestle
- mixing powdered substances without grinding
What is geometric dilution?
- done when a small amount of a substance has to be mixed with a large amount
- take equivalent parts of the large amount and add to smaller amount
- grind until homogeneous
What is a glass mortar and pestle used for?
- mixing amorphous (soft) powders
- incorporating powders into liquids or ointments
- for colored substances (will stain porcelain ones)
What is a porcelain mortar and pestle used for?
- comminution of crystalline substances
- primary emulsions
When should stainless steel spatulas not be used?
- when working with materials that may stain or corrode
- when trace amounts of metal are harmful to the patient
What is levigation?
- mixing a powder with a small amount of liquid or a semi-solid
- powder in insoluble to form a smooth paste
- can use mortar and pestle or spatula and table
- use to reduce partible size
What glassware is associated with TD?
TC?
TD- burettes, pipettes, syringes
TC- volumetric flasks, graduated cylinders
