A biochemist needs a medium for acid-producing bacteria. The pH of the medium must not change by more than 0.05 pH units for every 0.0010 mol of H₃O⁺ generated by the organisms per liter of medium. A buffer consisting of 0.10 M HA and 0.10 M A⁻ is included in the medium to control its pH. What volume of this buffer must be included in 1.0 L of medium?