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Answer the following.
Calculate the boiling point of urea solution when of urea is dissolved in of water. ( , boiling…
Calculate the boiling point of urea solution when $6\text{ g}$ of urea is dissolved in $200\text{ g}$ of water.
($K_b\text{ for water} = 0\cdot52\text{ K kg mol}^{-1}$, boiling point of pure water = $373\text{ K}$, mol. wt. of urea = $60$)
Answer
Answer
AIFormulas used: Molality: m = w2/(M2*w1) with M2 = 60 g mol^-1, w1 = 200 g, w2 = 6 g, so m = 0.5 mol kg^-1 Elevation of boiling point: dTb = i*Kb*m with m = 0.5 mol kg^-1, Kb = 0.52 K kg mol^-1, so dTb = 0.26 K
Formula: $\Delta T_b = K_b \times m$, where $m = \dfrac{w_2 \times 1000}{M_2 \times w_1}$
$m = \dfrac{6\text{ g}}{60\text{ g mol}^{-1} \times 0\cdot2\text{ kg}} = 0\cdot5\text{ mol kg}^{-1}$
$\Delta T_b = 0\cdot52\text{ K kg mol}^{-1} \times 0\cdot5\text{ mol kg}^{-1} = 0\cdot26\text{ K}$
$T_b = 373 + 0\cdot26 = 373\cdot26\text{ K}$
Final answer: 373.26 K
From ISC 2019 Chemistry Paper 1, question 1(d)(iii).
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