Laboratory Basics Flashcards
metric system
a standardized system of measurements used my scientists
what numerical factor is the metric system based off of?
factors of 10
name the prefix’s on the metric system in order from largest to smallest
kilo, base unit, centi, milli, micro, and nano
kilo
k, 1000, 1 x 10^3
base unit
no prefix, 1, 1 x 10^0
centi
c, 0.01, 1 x 10^-2
milli
m, 0.001, 1 x 10^-3
micro
u, 0.000001, 1 x 10^-6
nano
n, 0.000000001, 1 x 10^-9
what is the basic unit for length?
meter
1m = 100cm = 1000mm
what is the basic unit for mass?
gram
1g = 1cm^3 of H2O at 4 degrees Celsius
what is the basic unit for volume?
liter
1L = 1000mL = 1 kg of H2O at 4 degrees Celsius
accuracy
how close your data is to the correct or accepted value
precision
how reproducible your results are
how to you measure an item on a balance or scale?
zero > tare
what four items are used for holding liquids?
beakers, flasks, bottles, and test tubes
what two items are used for measuring liquids?
graduated cylinders and pipettes
outside of glassware what two items are used to dispense liquids?
transfer pipettes and micro-pipettes
what volume of liquid does a graduated cylinder hold?
5ml to 5L
what volume of liquid does a graduated pipette hold?
1mL to 25mL
what are the common sizes of a graduated pipette?
1mL, 2mL, 5mL, 10mL, 25mL
graduated pipettes are to be used in conjunction to what?
pipette pump
how many solutions can you use with a transfer pipette?
one solution
what volume of liquid does a micro-pipette hold?
0.1 uL to 1mL
how much liquid does a p-1000 measure? and where can it be found?
from 100uL to 1000uL (1mL)
tips found in the blue box
how much liquid does a p-100 measure? and where can it be found?
from 10uL to 100uL
tips found in the yellow box
how much liquid does a p-10 measure? and where can it be found?
from 1uL to 10uL
tips found in the pink box
solution
composed of one or more substances dissolved in liquid
solute
the substance being dissolved
solvent
the medium the substance is dissolved in
percent solutions
based on a ratio “X” parts per 100 parts
percent solutions are usually a volume of what?
100mL
what two units can percent solutions be measured in?
w/v and v/v
molarity
the number of moles of solute per 1 liter of solution
what is the formula for molarity?
moles of solute / liters of solution
what did you do in exercise 1a?
- measure mass of 10 drops
- checked for a precision
what did you do in exercise 1b?
- measured liquids using micro-pipettes
- calculated percent error
how do you calculated percent error?
actual mass - expected mass |
——————————————— x 100
expected mass
what did you do in exercise III?
- made a solution using NaCl and checked its mass
what did you do in exercise IV?
- dilluted the 2M of NaCl in 40mL and check for its mass
what did you so in exercise V?
- used the spectrophotomer
- diluted the test solution and rechecked the absorption value
what does a spectrophotomer do?
passes visible light through a solution and determines how much of that light (which is wavelengths) is absorbed and/or transmitted
what does absorption spectrum show?
the range of wavelengths a solution absorbs
if you know the wavelength that produces the peak absorbance of a substance, what can use the spectrophotomer to do?
set it to the wavelength to measure the amount of that substance in a solution
