Question

What mass of ethylene glycol (molar mass = 62.0 g mol^–1) must be added to 5.50 kg of water to lower the freezing point of water from 0°C to – 10.0°C? (K_f for water = 1.86 K kg mol^–1)

Answer 1

We know that,

Comments

Why deltaTf is 10K

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delta Tf is 10K because,
delta Tf= Tf° - Tf
and here, Tf° = 273K (0°C)
                    Tf = 263K (-10°C)
So, delta Tf = Tf° - Tf
                       = 273K - 263K
                       = 10K ✓