This isn’t scientific – two alkaline solutions mixed together should actually turn into an acidic substance
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This post was last edited by Shuizhu@Chenfu on 2021-9-28 09:29. When preparing calcium chloride coolant, I used sodium tetraborate as a corrosion inhibitor; however, an unexpected situation occurred. I would like to ask everyone for advice: 1. When 43g of anhydrous calcium chloride is added to 100g of water and dissolved, the pH value is 8.2. Upon gradually adding 1g of sodium tetraborate, the pH value decreases, eventually reaching 5.2. 2. In another container, add 100 g of water and 1 g of sodium tetraborate; after dissolution, the pH value is 9.2. Then add 43 g of anhydrous calcium chloride, and the pH value finally drops to above 5.3. In all cases, the same anhydrous calcium chloride and sodium tetraborate were used, as well as pure water. The pH meter was calibrated using standard solutions of 4.0 and 6.82. This isn’t scientific – two alkaline solutions mixed together should actually turn into an acidic substance
Has a reaction taken place to produce acid?
Did you not study chemistry in college, or did you not come into contact with chemistry in high school? Your big red headline is a complete misrepresentation of the facts. When an aqueous solution of sodium tetraborate reacts with an aqueous solution of calcium chloride, calcium borate and sodium chloride are formed; ignoring the by-products, the reaction proceeds in roughly this manner. Firstly, calcium chloride is a salt (a salt in chemistry), and it belongs to the category of salts formed from strong acids and weak bases; its pH is usually around 5-6. Since your sample has a pH of around 8.2, this indicates that the calcium chloride contains some alkaline substances. Do you know? Under normal conditions, it is acidic, not alkaline
I know that calcium chloride is slightly acidic, but the pH value when I prepared the mixture was indeed 8.2; after adding sodium tetraborate, the pH dropped to 5.2. The pH of sodium tetraborate alone is 9.2. If this weren’t the case, I wouldn’t have posted anything about it.