Measurement

Question 0

Why must balances be calibrated to the altitude they’re being used in?

Answer 0

Because gravity changes with altitude.

Calibrate for proper weights

Question 1

What causes inaccuracy or imprecision in electric balances?

Answer 1

• ferromagnetic samples
• dust lodged between permanent magnet and electromagnet
• temperature

Question 2

What are the 3 equations that contain % error?

Answer 2

% error = error of measurement/qty desired

% error = SR/qty desired

LWQ = SR/% error

Question 3

What is trituration?

Answer 3

• reducing particle size by grinding in a mortar and pestle

- mixing powdered substances without grinding

Question 4

What is geometric dilution?

Answer 4

• 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

Question 5

What is a glass mortar and pestle used for?

Answer 5

• mixing amorphous (soft) powders
• incorporating powders into liquids or ointments
• for colored substances (will stain porcelain ones)

Question 6

What is a porcelain mortar and pestle used for?

Answer 6

• comminution of crystalline substances

- primary emulsions

Question 7

When should stainless steel spatulas not be used?

Answer 7

• when working with materials that may stain or corrode

- when trace amounts of metal are harmful to the patient

Question 8

What is levigation?

Answer 8

• 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

Question 9

What glassware is associated with TD?

TC?

Answer 9

TD- burettes, pipettes, syringes

TC- volumetric flasks, graduated cylinders