What is the maximum volume (in mL) of 1.50 M HBr that can be added to 100 mL of a HEPES buffer solution that contains 0.040 mol HEPES weak acid and 0.030 mol HEPES weak base before depleting the buffer capacity?   

Please give your answer to two significant figures.

Wat is die maksimum volume (in mL) van 1.50 M HBr wat by 100 mL van 'n HEPES-bufferoplossing gevoeg kan word wat 0.040 mol HEPES swak suur en 0.030 mol HEPES swak basis bevat voordat die bufferkapasiteit uitgeput word?