Determination of sulfuric acid, nitric acid, and hydrofluoric acid in etch solutions
AN-H-114
vi
<p>Two separate titration sequences are required to analyze the mixture:</p><p><br />- titration of the HF content with Al(NO<sub>3</sub>)<sub>3</sub> (the «elpasolite» reaction)<br />- titration of the H<sub>2</sub>SO<sub>4</sub> with BaCl<sub>2</sub> followed by titration with NaOH to determine the «total acids» content</p><p><br />The HF, H<sub>2</sub>SO<sub>4</sub>, and «total acids» contents are converted to a HNO<sub>3</sub> equivalent, with the HNO<sub>3</sub> content found by subtracting the HF and H<sub>2</sub>SO<sub>4</sub> from the «total acids» content.<br /> </p>
Two separate titration sequences are required to analyze the mixture:
- titration of the HF content with Al(NO3)3 (the «elpasolite» reaction)
- titration of the H2SO4 with BaCl2 followed by titration with NaOH to determine the «total acids» content
The HF, H2SO4, and «total acids» contents are converted to a HNO3 equivalent, with the HNO3 content found by subtracting the HF and H2SO4 from the «total acids» content.