Passage III
A mole is 6 x 1023 molecules or formula units of a compound. Thus, the number of sucrose molecules in 1 mole of sucrose equals the number of NaCl units in 1 mole of NaCl. Molality (m) is a unit of concentration defined as:
When a substance is dissolved in a solvent, the freezing and boiling points of the solution will differ from those of the pure solvent. These changes depend on the concentration show how the freezing point and the boiling point, respectively, of H2O at 1 atm of pressure vary with concentration for 3 solutes.
17. A student claimed that, per formula unit, adding NaCl changes the boiling point of H2O more than adding CaCl2. Does Figure 2 support this claim?
Your Answer is
Correct Answer is A
Explanation
At 1 atm, the boiling point of water is 100°C. Look at figure 2, when the concentration of the abscissa is also 0.20 m, the boiling point of the CaCl2 solution is higher, so the question stem is wrong, choose No