H3po4 Ph

Phosphoric acid

h3po4 ph Introduction:

Phosphoric acid is a common inorganic acid and is a moderately strong acid. Its acidity is weaker than strong acids such as sulfuric acid, hydrochloric acid, and nitric acid, but stronger than weak acids such as acetic acid, boric acid, and carbonic acid.

h3po4 ph use:

In the production of silicon flat tubes and integrated circuits, aluminum film is commonly used as electrode leads, requiring photolithography of the aluminum film and the use of phosphoric acid as an acidic cleaning and corrosive agent. Can be used in combination with acetic acid.

h3po4 ph Content analysis:

The capacity method shall be determined according to the weight method procedure mentioned above, and shall be rotated 3-4 times during the cooling process. The following operations shall be carried out according to the following measurement procedure. Filter with a filter covered with filter paper, defatted cotton, or pulp. First, filter the upper clear liquid, wash the precipitate 3-4 times using the pouring method, using about 25-30ml of water each time. Then transfer the precipitate to the filter and continue washing with water until there is no acidity (take about 20ml of the washing solution, add one drop of mixed indicator and one drop of 0.25mol/L sodium hydroxide solution, the color of which is similar to the color of the treated same body of accumulated water). Transfer the precipitate into the original beaker, add 100ml of water without carbon dioxide, stir well, add about 10ml of 0.5ml/L sodium hydroxide standard solution, stir thoroughly until the precipitate dissolves, add 5 drops of mixed indicator, and titrate with 0.25mol/L hydrochloric acid standard solution. The endpoint is when the solution changes from purple to slightly yellow. Perform a blank test using the same measurement procedure.

The phosphoric acid content is calculated using the following formula: H3PO4 (%)=c (V1-VV2) x 0.003769/G x 50/500 x 20/500 x 100

In the formula, c - concentration of sodium hydroxide standard solution, mol/L;

V1- Volume of sodium hydroxide standard solution consumed by the sample, ml;

V2- Volume of hydrochloric acid standard solution consumed by the sample, ml;

V - In the blank test, 1m1 hydrochloric acid standard solution is equivalent to the volume of sodium hydroxide standard solution, in ml;

0.003769- mass of millimoles of phosphoric acid, g;

G is the amount of sample taken, g.

When this method is used for parallel measurement, the allowable error is within 0-2%.

FAO/WHO titration method: Take 1.00g of the sample and place it in a glass stoppered flask. Add about 100ml of water, and then add 0.5ml of thymolphthalein test solution (TS-248). Titrate with 1mol/L sodium hydroxide solution. Each ml is equivalent to H3PO40.049g.

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