**PROBLEM SOLVING : Normality, Molarity, Percentages**

1. WRITE
DOWN FORMULA 1

^{ST}.
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**