Question

What is the relation between molar mass of solute and boiling point elevation of solution?

• A. M2 = $\frac {1000\ △T_bW_2}{K_bW_1}$
• B. M2 = $\frac {1000\ K_bW_2}{△T_bW_1}$
• C. M2 = $\frac {△T_bW_1}{1000\ K_bW_2}$
• D. M2 = $\frac {1000\ K_bW_1}{△T_bW_2}$

Answer 1

Answer: (B)

M2 = $\frac {1000\ K_bW_2}{△T_bW_1}$

Answer 2

The relation between the molar mass of the solute (M2) and the boiling point elevation of the solution (△Tb) can be given by the equation:
△Tb = $\frac {K_b . M_2 . W_2}{W_1}$
where:
△Tb is the boiling point elevation of the solution,
Kb is the molal boiling point elevation constant,
M2 is the molar mass of the solute,
W2 is the weight (mass) of the solute,
and W1 is the weight (mass) of the solvent.
To convert the equation into a more convenient form, we can multiply both sides by 1000:
1000 . △Tb = $\frac {1000 .K_b . M_2 .W_2}{W_1}$
Simplifying, we have:
M2 = $\frac {1000 . K_b . W_2}{△T_b . W_1}$
We can see that the correct relation is option (B): M2 = $\frac {1000 . K_b . W_2}{△T_b . W_1}$