Lecture 2 Flashcards
1
Q
Sensitivity
A
- minimum amount of X needed to record a positive result
2
Q
Specificity
A
- a positive result only comes from a truly positive sample
3
Q
Random Error
A
- new error introduced with each measurement
- variability present
- not reproducible
4
Q
Systematic Error
A
- error that is consistently present
- result is always the same
- consistent
- reproducible
5
Q
Accuracy
A
- how close a recorded value is to the true value
- a single measurement
6
Q
Precision
A
- how reliably you can measure a value
- multiple measurements
- clustered together with similar results
7
Q
Significant Figures
A
- many measurements have a set level of precision/accuracy
- round the correct sig figs at end of all calculations
8
Q
Units of Measurements
A
- when a value requires the use of scientific notation it common to change the unit of measurement
9
Q
pH Meter
A
- fragile glass probe permeable to H+
- current produced by probe is compared against standards to report pH value
- probe rinsed and stored in solution between uses (KCl or acidic buffer)
10
Q
pH Meter Random Error
A
- taking measurement before things have adequately mixed
- taking reading too early
- contamination
11
Q
pH Meter Systematic Error
A
- calibrated incorrectly
12
Q
Scale
A
- primarily used to weigh chemicals for making lab solutions
- scale must be tared/zeroed with empty container to obtain accurate measurements
13
Q
Scale Errors
A
- systematic: not zeroing off
- random: accidentally place extra sheet
14
Q
Vortex Mixer
A
- used to mix small quantities of solutions
- setting for mixing speed and continuous or touch operation
- may be invaluable to mix some solutions and damaging to others
15
Q
Stir Plate
A
- Teflon coated magnets placed in solution
- magnet in base with adjustable spin speed
- sometimes coupled with a heating element to aid in dissolving solutes
