Module 2: Preparation and Standardization of 0.1 N Sodium hydroxide Solution Flashcards
“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
QUANTITATIVE TRANSFER
In standardization,
the “concentration” of a solution is “determined” by titrating it against a _______
primary standard
standards that are solid
Primary Standard
highly purified compound that serves a reference material
Primary Standard
In the experiment, the “concentration” of the “unknown” solution is determined by titrating it against ____________
another standard solution
point where physical change occurs
end point
Standardization of 0.1 N NaOH
UNKNOWN (Not Standardized yet)
0.1N NaOH
(Base)
STANDARD WORKING SOLUTION
standards that are liquid
Secondary Standard
indicator Standardization of 0.1 N Sodium hydroxide Solution
phenolphthalein
The prepared NaOH solution was standardized using?
0.1 N sulfuric acid
Titrated color
permanent faint pink color
Solution of unknown purity but known concentration (Not yet Standardized)
STANDARD WORKING SOLUTION
Standardization of 0.1 N NaOH
KNOWN (Solution, Known Concentration – Standardized
from Lesson 2)
0.1N H2SO4
(Acid)
SECONDARY STANDARD
Dried solid
PRIMARY STANDARD
A highly pure substance
PRIMARY STANDARD
__________ is a substance whose content/purity/concentration has been found by comparison against a primary standard.
SECONDARY STANDARD
– Remember: H2SO4 was standardized
using Na2CO3 (a primary standard)
Is 0.1 N sulfuric acid used as a primary standard?
(Yes or No)
No
Sulfuric acid solution is considered a
SECONDARY STANDARD
Standard Solution (liquid)
SECONDARY STANDARD
Usually, a solution with known concentration
SECONDARY STANDARD
Ex. Sulfuric acid
SECONDARY STANDARD
Ex. Sodium carbonate
PRIMARY STANDARD
Potassium biphthalate, KHC8H4O4
(KHP), MW=204.22 g/mol
– As _________________
Primary standard
HCl solutions and H2SO4 solutions
– As __________________
Secondary standard
Indicator
Phenolphthalein
Endpoint
Permanent faint pink
Equations
𝑵𝟏𝑽𝟏 = 𝑵𝟐𝑽𝟐
𝑵𝒂𝑽𝒂 = 𝑵𝒃𝑽𝒃
Normality equation for standard working solution
𝑵𝒃 = 𝑵𝒂𝑽𝒂
————
𝑽𝒃
𝑵𝒂 stands for
Normality of H2SO4
𝑽𝒂 stands for
Volume of H2SO4 used
𝑽𝒃 stands for
Volume of NaOH used
Do you need to calculate for the mEq wt of sulfuric acid?
(Yes or No)
No.
Only the volume and concentration of the solution are needed.
𝑵𝟏𝑽𝟏 = 𝑵𝟐𝑽𝟐
Make sure to substitute the correct normality and volume in each solution. Do not interchange them.
Careful!
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.
Important
The concentration of a solution can also be
determined by titrating it against another
standard solution, a ___________
secondary standard
The ______ is the standard working solution
while the _______ is a secondary standard
- titrant
- titrand
Normality of the solution can be calculated
using the equation
𝑵𝒃 = 𝑵𝒂𝑽𝒂
———– If the unknown solution is a base
𝑽𝒃
𝑵𝒂 = 𝑵𝒃𝑽𝒃
———– If the unknown solution is an acid
𝑽𝒂
