The vapor pressure of a solution of KBr in water and ethanol (CH₃CH₂OH) is 151 mm Hg at 50.0 °C and 374 mm Hg at 70.0 °C. What is the mass percent of KBr, water, and ethanol in the solution if water has a vapor pressure of 92.5 mm Hg at 50 °C and 234 mm Hg at 70 °C, while ethanol has a vapor pressure of 220 mm Hg at 50 °C and 541 mm Hg at 70 °C?

• A. 24.9% KBr, 24.3% water, 50.8% ethanol
• B. 7.60% KBr, 51.4% water, 41.0% ethanol
• C. 22.5% KBr, 18.4% water, 59.1% ethanol
• D. 7.60% KBr, 41.0% water, 51.4% ethanol

Answer: (C)