Chapter 5: Laboratory Mathematics and Solution Preparation

Question 1

How many micrometers are in a centimeter?

Answer 1

10,000.

Question 2

How many micrometers are in a meter?

Answer 2

1,000,000.

Question 3

How many pounds are in a kilogram?

Answer 3

2.2lb.

Question 4

How many cubic centimeters are in a liter?

Answer 4

0.001L because 1cc=1ml.

Question 5

Why are buffered solutions important?

Answer 5

So that the solution can resist pH changes when a weak acid or base is added.

Question 6

When 1 formula weight (gram molecular weight) of a chemical is dissolved in 1L of solution, it is called a:

Answer 6

Molar solution.

Question 7

How would you make a 2.0M NaCl solution with: Na=23 and Cl=35.5)?

Answer 7

You add the molecular weight (Na+Cl) then times it by 2 to get 117.0g of NaCl diluted up to 1L.

Question 8

What is considered an acidic pH?

Answer 8

A pH of less than 7.

Question 9

To prepare a normal solution of Na2SO4 with Na=23, S=32 and O=16, how much would you add?

Answer 9

(23+23)+32+(16+16+16+16)= 142 and the equivalent weight is 71g, so 71g to a total volume of 1L.

Question 10

3.75 mL of ammonium hydroxide diluted to 500 mL is equal to:

Answer 10

3.75/500=0.75% solution.

Question 11

How many microliters is in a mililiter?

Answer 11

1microliter-0.001mL.

Question 12

2 mL of a 1:50 dilution of Ab are needed. If beginning with an undiluted Ab, what dilution would be correct?

Answer 12

1000/50=20mL*2=40mL

Question 13

How do you convert F to C?

Answer 13

68*(CX9/5) +32

Question 14

Convert 20F to C:

Answer 14

68* (20*9/5) +32=-6.6

Question 15

Convert 3in to cm:

Answer 15

(2.54*3)= 7.6cm

Question 16

How many mL will a 5% solution of 2.5g make?

Answer 16

50.

Question 17

How do you determine a definite amount of percentage solution?

Answer 17

% desired X 100= g or ml of solute needed.

Question 18

How do you make a dilution from an already prepared stock solution?

Answer 18

Beginning % X beginning volume= Desired % X desired volume. Just fill in any unknown variables and balance the equation as needed.

Question 19

What is the gravimetric factor?

Answer 19

A method for compensating for variables in the actual dye content of dry dyes used in the preparation of staining solutions.

Question 20

How do you calculate the gravimetric factor?

Answer 20

(Concentration of present dye)/(Concentration of new dye)= Gravimetric factor.