10 ml of a mixture of phosphoric acid and sulfuric acid is placed in an erlenmeyer flask; add excess sodium chloride and cool. A 0.10 normal NaOH solution was titrated using a phenolphthalein indicator color, and 30 mL was used. The operation is repeated using the methylorange indicator color, and for neutralization 23 mL is required. Calculate the concentration of each of the acids in L-1.Data: In the presence of phenolphthalein we have the consumption of: all H2SO4 and 2H + of H3PO4. While in the presence of methylorange, we have the consumption of: all H2SO4 and 1H + of H3PO4.Note: The solid NaCl is placed in order to avoid the hydrolysis of the monosodium disodium phosphates (common ion effect), which would alter the pH of the medium. Refrigerate to avoid H2SO4 reaction with NaCl.Answer: 6.86 g of H 3 PO 4 / L and 7.84 g of H 2 SO 4 / L

Dirceu Reforco Escolar , 7 Years ago

Grade 6