Module 2: Preparation and Standardization of 0.1 N Sodium hydroxide Solution

Question 1

“Transfer” of a substance from one container or vessel to another such WITHOUT LOSING the content by;
– rinsing the original vessel, and
– adding the washings to the receiving vessel

Answer 1

QUANTITATIVE TRANSFER

Question 2

In standardization,

the “concentration” of a solution is “determined” by titrating it against a _______

Answer 2

primary standard

Question 3

standards that are solid

Answer 3

Primary Standard

Question 3

highly purified compound that serves a reference material

Answer 3

Primary Standard

Question 4

In the experiment, the “concentration” of the “unknown” solution is determined by titrating it against ____________

Answer 4

another standard solution

Question 4

point where physical change occurs

Answer 4

end point

Question 4

Standardization of 0.1 N NaOH

     UNKNOWN (Not Standardized yet)

Answer 4

0.1N NaOH
(Base)

STANDARD WORKING SOLUTION

Question 4

standards that are liquid

Answer 4

Secondary Standard

Question 5

indicator Standardization of 0.1 N Sodium hydroxide Solution

Answer 5

phenolphthalein

Question 6

The prepared NaOH solution was standardized using?

Answer 6

0.1 N sulfuric acid

Question 6

Titrated color

Answer 6

permanent faint pink color

Question 7

Solution of unknown purity but known concentration (Not yet Standardized)

Answer 7

STANDARD WORKING SOLUTION

Question 7

Standardization of 0.1 N NaOH

                             KNOWN (Solution, Known Concentration – Standardized 
                         from Lesson 2)

Answer 7

0.1N H2SO4
(Acid)

SECONDARY STANDARD

Question 7

Dried solid

Answer 7

PRIMARY STANDARD

Question 8

A highly pure substance

Answer 8

PRIMARY STANDARD

Question 8

__________ is a substance whose content/purity/concentration has been found by comparison against a primary standard.

Answer 8

SECONDARY STANDARD

– Remember: H2SO4 was standardized
using Na2CO3 (a primary standard)

Question 8

Is 0.1 N sulfuric acid used as a primary standard?

(Yes or No)

Answer 8

No

Sulfuric acid solution is considered a
SECONDARY STANDARD

Question 8

Standard Solution (liquid)

Answer 8

SECONDARY STANDARD

Question 8

Usually, a solution with known concentration

Answer 8

SECONDARY STANDARD

Question 9

Ex. Sulfuric acid

Answer 9

SECONDARY STANDARD

Question 9

Ex. Sodium carbonate

Answer 9

PRIMARY STANDARD

Question 9

Potassium biphthalate, KHC8H4O4
(KHP), MW=204.22 g/mol
– As _________________

Answer 9

Primary standard

Question 10

HCl solutions and H2SO4 solutions
– As __________________

Answer 10

Secondary standard

Question 11

Indicator

Answer 11

Phenolphthalein

Question 12

Endpoint

Answer 12

Permanent faint pink

Question 13

Equations

Answer 13

𝑵𝟏𝑽𝟏 = 𝑵𝟐𝑽𝟐

𝑵𝒂𝑽𝒂 = 𝑵𝒃𝑽𝒃

Question 14

Normality equation for standard working solution

Answer 14

𝑵𝒃 = 𝑵𝒂𝑽𝒂
————
𝑽𝒃

Question 15

𝑵𝒂 stands for

Answer 15

Normality of H2SO4

Question 16

𝑽𝒂 stands for

Answer 16

Volume of H2SO4 used

Question 17

𝑽𝒃 stands for

Answer 17

Volume of NaOH used

Question 18

Do you need to calculate for the mEq wt of sulfuric acid?

(Yes or No)

Answer 18

No.

Only the volume and concentration of the solution are needed.

Question 19

𝑵𝟏𝑽𝟏 = 𝑵𝟐𝑽𝟐

Make sure to substitute the correct normality and volume in each solution. Do not interchange them.

Answer 19

Careful!

Question 20

Update the label of the prepared and standardized solution (now a standard solution) with the calculated AVERAGE
normality.

– In this case, it’s 0.09351 N NaOH.
– This value will be used in the
assay of milk of magnesia.

Answer 20

Important

Question 21

The concentration of a solution can also be
determined by titrating it against another
standard solution, a ___________

Answer 21

secondary standard

Question 22

The ______ is the standard working solution
while the _______ is a secondary standard

Answer 22

1. titrant
2. titrand

Question 23

Normality of the solution can be calculated
using the equation

Answer 23

𝑵𝒃 = 𝑵𝒂𝑽𝒂
———– If the unknown solution is a base
𝑽𝒃

𝑵𝒂 = 𝑵𝒃𝑽𝒃
———– If the unknown solution is an acid
𝑽𝒂