Chapter 5: Laboratory Mathematics and Solution Preparation Flashcards
How many micrometers are in a centimeter?
10,000.
How many micrometers are in a meter?
1,000,000.
How many pounds are in a kilogram?
2.2lb.
How many cubic centimeters are in a liter?
0.001L because 1cc=1ml.
Why are buffered solutions important?
So that the solution can resist pH changes when a weak acid or base is added.
When 1 formula weight (gram molecular weight) of a chemical is dissolved in 1L of solution, it is called a:
Molar solution.
How would you make a 2.0M NaCl solution with: Na=23 and Cl=35.5)?
You add the molecular weight (Na+Cl) then times it by 2 to get 117.0g of NaCl diluted up to 1L.
What is considered an acidic pH?
A pH of less than 7.
To prepare a normal solution of Na2SO4 with Na=23, S=32 and O=16, how much would you add?
(23+23)+32+(16+16+16+16)= 142 and the equivalent weight is 71g, so 71g to a total volume of 1L.
3.75 mL of ammonium hydroxide diluted to 500 mL is equal to:
3.75/500=0.75% solution.
How many microliters is in a mililiter?
1microliter-0.001mL.
2 mL of a 1:50 dilution of Ab are needed. If beginning with an undiluted Ab, what dilution would be correct?
1000/50=20mL*2=40mL
How do you convert F to C?
68*(CX9/5) +32
Convert 20F to C:
68* (20*9/5) +32=-6.6
Convert 3in to cm:
(2.54*3)= 7.6cm
How many mL will a 5% solution of 2.5g make?
50.
How do you determine a definite amount of percentage solution?
% desired X 100= g or ml of solute needed.
How do you make a dilution from an already prepared stock solution?
Beginning % X beginning volume= Desired % X desired volume. Just fill in any unknown variables and balance the equation as needed.
What is the gravimetric factor?
A method for compensating for variables in the actual dye content of dry dyes used in the preparation of staining solutions.
How do you calculate the gravimetric factor?
(Concentration of present dye)/(Concentration of new dye)= Gravimetric factor.
