Answer:
32 g
Explanation:
The increase in the boiling point of X can be calculated using the following expression.
ΔT = Kb × b
where,
ΔT: increase in the boiling point
Kb: molal boiling point constant (0.62 °C.kg/mol) (I looked it on the web)
b: molality of the solute
ΔT = Kb × b
(124.7°C - 124.2°C) = (0.62 °C.kg/mol) × b
b = 0.81 mol/kg
The mass of X is 650 g (0.650 kg). Then, the moles of urea (solute) are:
[tex]\frac{0.81molUrea}{1kgX} .0.650kgX=0.53molUrea[/tex]
The molar mass of urea is 60.06 g/mol. The mass of urea is:
[tex]0.53mol.\frac{60.06g}{mol} =32g[/tex]
The mass of urea that was dissolved is 32 g.
This is the temperature in which a liquid starts changing to vapor or gas.
Increase in the boiling point of X = ΔT = Kb × b
where ΔT is increase in the boiling point, Kb is molal boiling point constant (0.62 °C.kg/mol)
We can calculate the molality of the solute
ΔT = Kb × b
= (124.7°C - 124.2°C)
= (0.62 °C.kg/mol) × b
b = 0.81 mol/kg
The mass of X is 650 = 0.650 kg. Then, the moles of urea (solute) are:
0.81mol Urea /1kgX × 0.650kgX = 0.53molUrea
The molar mass of urea is 60.06 g/mol. Therefore the mass of urea is:
0.53mol × 60.06g/mol = 32g.
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