# General Chemistry/Reactions of Acids and Bases/Answers

 ${\displaystyle {\hbox{HPO}}_{4}^{2-}+{\hbox{OH}}^{-}\to {\hbox{PO}}_{4}^{3-}+{\hbox{H}}_{2}{\hbox{O}}}$ 1. Equimolar solutions of sodium biphosphate and potassium hydroxide are mixed. ${\displaystyle {\hbox{HPO}}_{4}^{2-}+{\hbox{H}}^{+}\to {\hbox{H}}_{2}{\hbox{PO}}_{4}^{-}}$ 2. Equimolar solutions of sodium biphosphate and hydrochloric acid are mixed. ${\displaystyle {\hbox{SO}}_{2}+{\hbox{OH}}^{-}\to {\hbox{HSO}}_{3}^{-}}$ ${\displaystyle {\hbox{HSO}}_{3}^{-}+{\hbox{H}}^{+}\to {\hbox{H}}_{2}{\hbox{SO}}_{3}}$ 3. Excess sulfur dioxide gas is bubbled into a dilute solution of sodium hydroxide. Acid is then added. ${\displaystyle {\hbox{Al}}^{3+}+3{\hbox{H}}_{2}{\hbox{O}}\to {\hbox{Al}}({\hbox{OH}})_{3}+3{\hbox{H}}^{+}}$ 4. Aluminum chloride is dissolved into water. ${\displaystyle {\hbox{NaF}}+{\hbox{H}}_{2}{\hbox{O}}\to {\hbox{Na}}^{+}+{\hbox{OH}}^{-}+{\hbox{HF}}}$ ${\displaystyle {\hbox{H}}^{+}+{\hbox{OH}}^{-}\to {\hbox{H}}_{2}{\hbox{O}}}$ 5. Sodium fluoride is dissolved into water. Strong acid is then added. ${\displaystyle {\hbox{SO}}_{3}+{\hbox{CaO}}\to {\hbox{CaSO}}_{4}}$ Neutral. Ca2+ is the conjugate of a strong base and SO42- is the conjugate of a strong acid. 6. Solid calcium oxide is exposed to a stream of sulfur trioxide gas. If the resulting compound is dissolved, will the solution be acidic, basic, or neutral? ${\displaystyle {\hbox{HCl}}+{\hbox{Ag}}^{+}\to {\hbox{H}}^{+}+{\hbox{AgCl}}}$ A cloudy precipitate forms, as silver chloride is not soluble. 7. Gaseous hydrogen chloride is bubbled into a solution of silver nitrate. ${\displaystyle {\hbox{NH}}_{4}^{+}+{\hbox{OH}}^{-}\to {\hbox{NH}}_{3}+{\hbox{H}}_{2}{\hbox{O}}}$ Gas bubbles form. 8. Ammonium chloride crystals are dissolved in water. Sodium hydroxide is then added. ${\displaystyle {\hbox{HCO}}_{3}^{-}+{\hbox{Ca}}^{2+}+{\hbox{OH}}^{-}\to {\hbox{H}}_{2}{\hbox{O}}+{\hbox{CaCO}}_{3}}$ A cloudy precipitate forms, as calcium carbonate is not soluble. Hint: The hydroxide reacts with the bicarbonate to form water, then the resulting carbonate reacts with calcium. 9. Calcium hydroxide crystals are dissolved into a solution of sodium bicarbonate. ${\displaystyle {\ddot {\hbox{P}}}{\hbox{H}}_{3}+{\hbox{AlCl}}_{3}\to {\hbox{H}}_{3}{\hbox{P}}-{\hbox{AlCl}}_{3}}$ They have formed a Lewis adduct. Aluminum chloride is a very strong Lewis acid. Phosphine is a Lewis base because there is a non-bonding pair of electrons on the P that can be donated. 10. Phosphine gas is sprayed onto pebbles of aluminum trichloride.