AIM 7 - Standard Solution

Topic Seven ~ Standard Solution

Molecule

-          aggregate of ≥ 2 atoms in definite arrangement held together by chemical forces

Molecular Formula

-          exact number of atoms for each element in a molecule

Molar mass

-          mass per mol (gram) = molecular mass (amu)

Molecule mass

-          Molecule  mass = ∑atomic mass

Fraction of element

-          Fraction A in A_xB_y = x Mw A / Mw A_xB_y

Stock Solution

-          Prepared by weighing out appropriate portion of pure solid, or;

-          Prepared by measuring appropriate volume of pure liquid, then diluted

Standard solution

-          Prepared by diluting stock solution

-          Esp. used in chemical analysis for standard curve

Stock Solution Preparation

1.       Calculate and weigh out Y gram.

2.       Dissolve it into water and add water till 1 liter.

3.       Concentration of chemical/nutrient is 1000mg/L, volume is one liter.

Standard Solution Preparation

-          C_SV_S = C_FV_F (Only valid if no chemical reaction)

Chemical Concentration Determination

-          Standard curve preparation

o   Needs a set of standard solutions

o   Specific reagent must react with solute in std solution

o   Reaction response determined by spectrophotometer

o   Analysis result plotted on graph for std curve

o   Estimation [con] based on of std curve slope (k)

o   A = k[con]

-          F-factor / A Comparison technique

o   Needs 1 solution

o   Estimation [con] based on direct proportional method after mixing

o   F = [std sol] / (Ab_s-Ab_b)

o   [solute] = F x (Ab_w-Ab_b)

Other Dilutions

-          Volume to Volume

o   Based on ratio à 1:10 = 1 part A + 9 parts B

-          Serial Dilution

Esp. for bacterial enumeration (CFU)