Calculation of Original pH from Final pH after Titration A biochemist has 200 mL of a 0.30 M solution of a weak acid with a pKa of 6.4. She adds 3.0 mL of 4.0 M HCl, which changes the pH to 5.8. What was the pH of the original solution?

a chemical reaction happens

explanation:

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.