GB/T 20166.1-2012Chemical analysis methods of rare earth polishing powder - Part 1: Determination of cerium oxide content - Titrimetry (English PDF)

3.1

phosphoric acid (rho1.69).

3.2

perchloric acid (rho1.5).

3.3

sulfate (rho1.84).

3.4

sulfate (1mol/L).

3.5 parathion mixed acid

70mL 15mL of water was added phosphoric acid (3.1) and 15mL sulfuric acid (3.3), were mixed.

3.6

ceric sulfate solution {c [Ce (SO4) 2] ~0.02mol/L}. Weigh 3.32g of anhydrous ceric sulfate in 250mL beaker, add

100mL sulfuric acid (3.4) was dissolved and transferred to 500mL volumetric flask, sulfuric acid (3.4) diluted to the mark, were mixed.

3.7 standard potassium dichromate solution c 16K2Cr2O

÷ 7 = 0.02mol/éë

êê

úúL. Weigh 0.9806g by 110 °C ~ 130 °C drying 2h of

Potassium dichromate (reference material), in the 250mL beaker, add 100mL water dissolved and transferred to 1000mL volumetric flask, dilute to the mark with water

Degrees were mixed.

3.8

ferrous ammonium sulfate standard solution [c (Fe2)] ~0.02mol/L.

3.8.1 preparation

Weigh 9g ferrous ammonium sulfate [(NH4) 2Fe (SO4) 2 · 6H2O] in 500mL beaker, add sulfuric acid (3.4) is dissolved,

Moved into 1000mL volumetric flask, dilute sulfuric acid (3.4) to the mark, were mixed.

3.8.2 Calibration

Pipette 20.00mL ferrous ammonium sulfate standard solution (3.8.1) 3 parts, were placed in three 250mL conical flask, add

10mL parathion mixed acid (3.5), add water to 100mL, add 4 drops of sodium diphenylamine solution (3.9), with standard potassium dichromate solution (3.7) drop

Blue and purple set to subside as the end point.

3.8.3

according to formula (1) to calculate c (Fe2) molar concentration of the standard solution (mol/L).

c (Fe2) = c 16K2Cr2O

÷ 7 V1 (1)

Where.

c 16K2Cr2O

÷ 7 --- volume concentration of potassium dichromate standard solution material, units of moles per liter (mol/L);