Respuesta :
The boiling point of the water by adding 2.5 moles of aluminium nitrate will be changed by 4°Celsius.
When sugar is dissolved in x kg of water:
ΔT₁ = 1°C = 274 K (0°C = 273 K)
Number of moles of sugar dissolved = 2.5 mol
i = Van't Hoff factor of sugar = 1
ΔT₁ = iKf × molality = iKf × moles of sugar/weight of solvent in kg
ΔT₁ = 274 K = 1 × Kf × 2.5 mol / xkg ---- (1)
When aluminium nitrate is dissolved in x kg of water:
Number of moles of aluminium nitrate dissolved = 2.5 mol
Al(NO₃)₃ (aq) = Al₃+ (aq) + 3NO₃⁻ (aq)
i = Van't Hoff factor of aluminium nitrate is 4
Aluminium nitrate being ionic compound will get dissociated into its constituting ions. The value of i of the ionic compound is equivalent to the number of discrete ions in a formula unit of a substance.
ΔT₂ = iKf × moles of Al (NO₃)₃ / weight of solvents in Kg
ΔT₂ = 4 × Kf × 2.5 mol / x Kg ---- (2)
On dividing 1 and 2 we get,
delta T₂ = 4 × 274 K = 4 × 1°C = 4°C
The boiling point of the water by adding 2.5 moles of aluminium nitrate will be changed by 4°C.
