Soil carbonate gas meter device GB9835-88 glass instrument

Topic Content and Scope of Application

This standard explains and specifies the principles, instruments, equipment, reagents, sample preparation, and measurement steps for soil carbonate determination. This standard is applicable for determining the carbonate content of all types of soils except magnesium carbonate soil.

2 Determination principle

The reaction between soil samples and hydrochloric acid produces carbon dioxide gas, which is equivalent in volume to the mass of calcium carbonate in the soil

The quality of calcium carbonate.

3 Soil carbonate gas meter device GB9835-88 glass instrument Instruments and equipment

3.1 Soil sieve: aperture 2mm, 0.2mm.

3.2 Analytical Balance: Sensitivity of 0.001 g.

3.3 Gas meter: 100mL tube, inner diameter 20mm, length 318mm, scale accuracy of 0.5mL, as shown in the schematic diagram.

4 reagents

4.1 Calcium carbonate (HG3-1066);

421:3 (V/V) hydrochloric acid solution (GB622);

4.30.1% (W/V) methyl red indicator: 95% ethanol solution;

4.4 Gas meter water: Add 1000mL of distilled water to 40mL of hydrochloric acid solution (4.2), and add 1mL of methyl red indicator (4.3).

5 Soil carbonate gas meter device GB9835-88 glass instrumentSelection and preparation of samples

Select representative samples of Fengqian soil, remove impurities such as stones, crush them through a 2mm sieve, and evenly extract about 20g from them

Grind everything through a 0.2mm sieve and put it into a grinding bottle for later use.

According to the carbonate content in the soil, determine the amount of sample to be weighed. The specific judgment method is: put 25mL hydrochloric acid solution (4.2) into a 50mL small beaker, add a small amount of soil sample to hydrochloric acid with a weighing spoon, and observe the degree of reaction foaming. If the foaming is severe and accompanied by a slight sound, and the carbonate content is above 10%, the sample size is 1-2g, accurate to 0.001g; if the foaming phenomenon is not visible, only a faint sound can be heard when close to the ear, and the carbonate content is below 1%, the sample size is increased to 5-10g, accurate to 0.001g; if the foaming degree is moderate, the sample size is 2-5g, accurate to 0.001g.

Weigh 0.300g anhydrous calcium carbonate to the nearest 0.001g and use it as a standard.