Question

A sample of potassium hydrogen phthalate, KHCxH404, normally used for the standardization of bases, was contaminated in a lab. A student found a previously standardized solution of NaOH that had a concentration of 0.025 mol L-'. The student used 44.80 mL of the NaOH to titrate a sample of the contaminated KHC8H404 and found that its percent purity was 89.2% by mass. What was the mass of the sample that was contaminated?

Answer 1

1000 KH Cq H4 O4 + Nadh kNaCo Hu Oy & H₂O moles of Naoh = moles of KHCg Hy 04 CNaOH X VinaOH = CKH cgH you XVk Heg 14404 0.025mx. 44.8 L = moles of KHCg Hy Oy moles of KHCS Hy by = 0,00112 mass = moles x molar mass (KHCS Hy 04) mass = 0.00112 x 204g/mol mass = 0.2289 percent furila - 89.2%. contaminant purity = 10.8% 89.2 x actual sample mass = 0.2289 100 aetaal sample mass = 0.2569 mass of contaminant => 10.8 x 0.2589 = 10.02769 MInc V 100