w5/w6 reagent preparation Flashcards
solution
mixture of substances has two parts a solute and a solvent
solute
substance that is dissolved so the NACL in a solution
solvent
substance that dissolves the water it would be distilled water
dilute solution
contain small portion of solute
concentrated solution
contain large portion of solute
diluent
agent that dilutes fluid
dilution
taking a measure of a concentrated solution and adding enough diluent to change the concentration to a lesser concentration
quantitative transfer what is it
preparing a reagent that is weighed and dissolved in a solvent to a specified concentration of volume you would
- calculations
- review WHIMIS AND SDS and make a workplace label
- accurately weigh solvent
- combine in a volumetric flask
- transfer to reagent for storage f
filtering solution
use medium retention filter if not specified. Whatman#1 fleet a diameter that will fit in funnel, fold paper in half twice and open into the funnel one layer thick on onside and three layers thick on the other side.
table one on page four look at and understand, can’t really be made into a flashcard
dont forget :P
rounding sig figs -if number to be dropped is five
you look at the number before 5 and you go to the nearest even number so 2.5 rounded to 2 and 1.5 is rounded to 2 as well
- number to be rounded increases by one if odd number
- number to be rounded stays the same if even number.
if number to be dropped is <5
less than five then the number to be rounded does not change 2.4 stays as 2
if number to be dropped is >5
greater than 5 the number to be rounded increases by 1
if the number to be dropped is 5 with digits after it
then the 5 is considered greater than 5 and the number will increase by one
2.15- round
2.2
2.25-round
2.2
6.6541-round
6.7
% weight per volume
%w/v=grams per 100ml of solution
used to express the concentration of solutions when a solid solute is mixed with a liquid solvent
-amount of solute placed in vessel and enough solvent added to desired volume- diluting to a final volume.
how would you perform calculation of % weight per volume
% weight is used as grams over 100ml and then that is = x amount of grams ( what you are looking for) over your desired volume then you would cross multiple to determine how many grams of solute you’d need
example of a % weight per volume question , how to solve
how would you prepare 500 ml of an 0.85% saline solution
you’d do 0.85/100= xgrams/500 then solve from there
what to do for mg% weight per volume
calculations are same as % weight per volume except you’d use mg over 100 ml and then you’d convert afterwards
what is % volume per volume
%v/v= mL per 100mL of solution
- expresses concentration and is used when a solution is a liquid solute in a liquid solvent.
- When making the desired volume of solute is placed in the graduated cylinder or flask then the solvent is added to the desired total volume - kind of like a dilution -same ratio as %w/v
how to calculate% v/v
the concentration that you want or desire is put over 100ml to make that percent of solution then the concentration of the total volume of the solution that you want, then you’d solve for the amount of liquid that you need to add to the amount of volume that you want to get the concentration that you want
ex: 200 ml of 60% alcohol
you would do 60/100=x/200
how would you prepare 250ml of 95% ethanol
95/100=x/250
you are assuming that the concentration of the ethanol that you are diluting is 100 percent and it wills specify if it is not and there is a different calculation for this
molar solutions
- mole is gram molecular weight of a substance
- one mole contains 6.022 x10 exponent 23 particles. and it is weight in grams
- molar mass is on periodic table – it is the elements number so you can find the molar mass of KNO3 by adding the values together.
molarity of a solution
ratio of number of moles of solute per litre of solution mol/l like concentration
a solution of 1 mole in 1L has a molarity of 1
ppm
parts per million -used for small concentrations
dilutions
making a weaker substance from a more concentrated one. they are written as a fraction. 1/4 1refers to liquid being diluted and the 4 refers to the total volume of the FINAL SOLUTION the difference so 3 would be the amount of diluent used
what dilution is made if 5ml of absolute ethanol added to 20ml of distilled water
solute volume/total volume
5ml/ 5ml+20 ml = 5 over 25 which is one fifth
-you have to add both amounts to determine the total volume
how would you make 1/2 dilution of serum
you’d pipette one 1ml of serum then add 1ml of water to make a total solution of 2ml
dilutions 1/x and preparing a volume
concentration is not changing but volume is changing
-so 1/5 dilution of bleach is what you want, how would you make say 250 ml of that you would do
1/5=x/250 ml you are solving for the amount of bleach needed to have a 1/5 dilution
how would you prepare 1L of 1/10 dilution of bleach
you would put 1/10=x/1000ml(convert) then solve so 100ml of bleach and 900 ml of water
how to determine concentration after a dilution
multiply the original concentration with the dilution so a 5% solution of HCL is dusted 2/5 so then just 5x2/5 is 2% it will always be less
how to determine concentration after multiple dilutions
multiply the original concentration by all the dilutions say 7% solution diluted 1/7 then 1/10 it would be a 0.1% solution
solution of 36% w/v solution has been diluted 1/8 what is the concentration of the diluted solution
38 x 1/8 is 4.5
when are patient specimens diluted
when analyze is too high to measure ( so this would mean that the instrument can’t pick it up) if 1/2 dilution is made to patients serum and the result was 16mmol this is technically incorrect, you need to correct the dilution.
how to correct dilution made on patient sample 1/2 dilution of patient serum, result is 17mmol/L
dilution concentration x dilution factor= original concentration
-the dilution factor would be the flipped fraction
17mmol/l x 2/1 = 34mmol/L and this value can be reported
how to change concentration
a stronger solution is diluted to make a specific amount of a weaker solution. the volume of one solution times the concentration of that solution equals the volume of the second solution times the concentration of the second solution-mumbojumbo
V(stronger)xC(stronger)=V(weaker)xC(weaker)
or V1C1=V2C2
INVERSE RELATIONSHIP
if the concentration is absolute you would use the v/v ratio to solve the problem.
how much 30% v/v alcohol is required to make 100ml of 3% alcohol, how to set up problem?
VsCs=VwCw
we dont know the volume of the stronger solution needed to make this
vs(30%)=(3%)(100) then you’d solve for the volume of the stronger solution
WHMIS 2015 info
federally and provincially legislated hazard info system started 1988. 2015 aligns with Globally Harmonized System classification and labelling of chemicals or GHS
3 components of whims
safety data sheets
labelling
worker eductation
what does WHMIS stand for
workplace hazardous material information system