You have learned that adding table salt, NaCl (58.44 g/mol, 2.16 g/cm³), to water (K_b = 0.52 $\degree$C/m) increases the temperature at which it boils.You decide to try cooking pasta faster at a higher temperature in boiling salty water.What increase in the boiling point do you expect if you add 1 tablespoon (1 tbsp = 14.8 cm³) of salt to one 8 oz cup of water (237 mL)?

Question

Quizplus · Accepted Answer

To calculate the increase in boiling point, we use the formula ΔT = i * K_b * m, where ΔT is the change in boiling point, i is the van't Hoff factor (which is 2 for NaCl, as it dissociates into Na+ and Cl-), K_b is the ebullioscopic constant of water (0.52 °C/m), and m is the molality of the solution. First, we find the mass of NaCl in grams using its density (2.16 g/cm^3) and the volume of 1 tablespoon (14.8 cm^3), which gives us 31.968 g of NaCl. Then, we convert this mass to moles (31.968 g / 58.44 g/mol = 0.547 moles). Next, we find the molality by dividing the moles of NaCl by the kilograms of water (0.237 kg), resulting in a molality of approximately 2.31 m. Finally, we calculate the increase in boiling point: ΔT = 2 * 0.52 °C/m * 2.31 m = 2.4 °C.

You Have Learned That Adding Table Salt, NaCl (58 °\degree° C/m) Increases the Temperature at Which It Boils

You Have Learned That Adding Table Salt, NaCl (58 $\degree$ C/m) Increases the Temperature at Which It Boils