Question

How many milliliters of 0.500M NaOH should be added to 10.0g of tris hydrochloride to give a pH of 7.60 in a final volume? "Tris", short for tris(hydroxy-methyl)aminomthane, is a widely used buffer. For simplicity you can write the formula as BH 1 MM tris=157.596 g/mol; pkel tris-8.072

Answer 1

Trid But realfl with NaOH to give B BHT+ NaOH Ž B+ H₂O + Nat Henderson Hastalbalch equation is used the pH of buffer to calculate pH = pla+ los molex of B moles of BH+ 7-60 = 8.072 + 109 moles of B moles of BHT la moles of B moles of BHT = 7.6-8.072

los moles of B moles of But -0.472 = 150.472 moles of B moles of BHT moles of B = 0.33729 moles of But =) moles of B= 0.33729 x moles of Bht Total moles of tris = moles of B t moles of BHT 10 g - molar mal = moles of B t moles of BHT 10.9 157.596 gmail = moles of Bt moles of BHT 0.06345 = moles of B t moles of BHT Substitute o

0.06394 = 0.33729xmoles of BHT + moled of BH' moles of But' = 0.06345 le 33729 = 0.04745 & moler of B = 0.33729 x 0.04745 = 0.016 No. of moles of B produced = 0.016 A. No. of moles of B produced = No. of moles of Nach added .. No. of moled of Nach added = 0.016 molen . volume of Naoh required = 0.016 moles 0. 5m -= 32mL .