George is making spaghetti for dinner. He places 4.01 kg of water in a pan and brings it to a boil. Before adding the pasta, he adds 58 g of table salt (NaCl)to the water and again brings it to a boil. The temperature of the salty, boiling water is ________°C. Assume a pressure of 1.00 atm and negligible evaporation of water. K_b for water is 0.52 °C/m. A)99.87 B)100.26 C)100.13 D)99.74 E)100.00

Question

Quizplus · Accepted Answer

The boiling point elevation can be calculated using the formula ΔT = i * Kb * m, where i is the van't Hoff factor (2 for NaCl), Kb is the ebullioscopic constant (0.52 °C/m), and m is the molality of the solution. The molality is calculated as moles of solute per kg of solvent. The moles of NaCl is 58 g / 58.44 g/mol = 0.993 moles. The molality is 0.993 moles / 4.01 kg = 0.247 m. Thus, ΔT = 2 * 0.52 °C/m * 0.247 m = 0.256 °C. The boiling point of water is elevated to 100 + 0.256 = 100.26 °C.

George Is Making Spaghetti for Dinner