Exam 1 Flashcards
1 ppm =
1 mg/ L or 1 microgram per mL
1 ppb =
1 nanogram per mL or 1 microgram per liter
what is an analytical balance?
The balance with an enclosed weighing compartment is known as an analytical balance
what is a precision or top loading balance?
one with an open weighing area
Most flasks bear the label “___” on their side which indicates that they are designed “_____” the stated volume of liquid
- TC
- to contain
A _______ pipet is calibrated to deliver one fixed volume while a _____ pipet or measuring pipet can deliver variable volumes just like a buret.
- transfer
- mohr
Pipets and burets are calibrated “________” “___” their indicated volume.
- to deliver
- TD
Micropipets deliver volume of ________ μL while microliter syringes range from _________ μL.
- 1- 1000
- 1 to 500
measurement uncertainties arise from what 2 general causes?
– limitations of the method
– experimental error
How do you calculate uncertainty when values are multiplied or divided?
convert the uncertainties into percent uncertainties, then take the square root of the sum of their squares, then multiply this uncertainty with the calculated measurement
how do you calculate standard deviation?
subtract the mean from the number you are calculating, square this, divide by one less than the total measurements, then take the square root
For an infinite set of data, the mean is designated by ____ (the population means) and the standard deviation is designated by ____ (the population standard deviation).
- μ
- sigma
RSD stands for:
relative standard deviation, or the coefficient of variation.
RSD =
s/x x 100
uncertainty decreases in proportion to ______
1/square root of n.
n is the number of measurements
