Monday, September 2, 2013

Problem Solving: Normality, Molarity, Percent Solution Problems


PROBLEM SOLVING : Normality, Molarity, Percentages

1.    WRITE DOWN FORMULA 1ST.
2.    SHOW COMPUTATIONS.
3.    ENCLOSE ANSWERS IN BOXES.

ATOMIC WEIGHTS:

Na = 23           H = 1               S = 32
Cl= 35.5          O = 16            

1.       If you weigh 10 g NaCl solution and dissolve it in 600 ml of diluent. ( 5 pts. each)

A.    What is the Molarity?

M= 10
       58.5
      0.6 L

ANSWER= M = 0.28 M NaCl


B.     What is the Normality?

N= M X v or factor

N= 0.28 X 1

ANSWER N = 0.28 N NaCl

C.     What is the percent solution?

% = Weight of solute X 100
        Total Volume of solution

% = 10 X 100
          600

ANSWER % = 1.67%


2.      What is the Molarity of a 2 N H2SO4 solution? ( 5 pts.)

M= N
       v (valence or factor)

M= 2
       2

ANSWER M = 1 M H2SO4

3.      What is the dilution if you add 0.25 ml of serum to 5.0 ml of diluent? ( 5 pts.)

0.25 mL =  1 part
5.0 mL =  20 parts
               1:21

ANSWER Dilution = 1:21

Or

Parts of diluent = 5/0/25

5  
0.25

= 20 parts of diluent

DILUTION FACTOR= parts of solute + parts of diluent

Dilution factor = 1 + 20 = 21

ANSWER Dilution = 1:21

4.    How would you prepare  1:6 serum dilution? ( 5 pts.)

THERE ARE VARIOUS WAYS TO PREPARE SERUM DILUTIONS:

THE SIMPLEST WAY IS TO CONSIDER 1 mL of SERUM AS 1 PART.
ANSWERS:

1mL of serum = 1 part
5 mL of NSS  =  5 parts
                           6 parts

Dilution = 1:6

0.25 mL of serum   = 1 part
0.25 X 5 = 2.25 mL= 5 parts
                                   6 parts

Dilution = 1:6


5.    How would you prepare a 0.85 % NaCl solution? (5 pts.)


W=(%) X Total volume of solution
                100


W= 0.85 X 100
           100

ANSWER W= 0.85 g NaCl diluted to 100 mL of water in a volumetric flask


6. What is the Normality of a 10% CaCl2 solution?

N= % X 10
         EW (MW/v)


N= 10 X 10
        111/2


ANSWER N = 1.80 N CaCl2

7. Convert 40 mEq/L of calcium to mg/dL

40 mEq  X   1L    X  20 mg (40 atomic weight / valence)
     L            10 dL      1 mEq


ANSWER= 80 mg/dL

Chitika

SEARCH ENGINE

Google
 

COPYRIGHT

Except for the outside links, printing and copying of the articles contained herein should cite this site as the source. For commercial purposes, the permission of the author should be sought first. You can leave a comment in any of the posts. Thank you.