The radiator of a motor car holds 10 liter of water if the vehicle is to be used in gulmarg where the lowest temperature is -10 degree celsius then how much ethylene glycol is to be added to the water filled in the radiator
Answers
Answer:
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Given: Amount of water held by the radiator = 10 liters
The lowest temperature in Gulmarg = -10°C
To Find: Amount of ethylene glycol to be added
Solution:
Let the mass of ethylene glycol be a
Some data that we should already know
Density of water = 1 g/ml
The freezing point of water = 0°C
Molal freezing point depression of water (kf) = 1.86 °C/m
Amount of water in ml = Amount of water in liters x 1000
Amount of water in ml = 10 x 1000
= 10000 ml
Mass = Volume x Density
Mass of water = 10000 x 1
= 10000g
ΔTf = i x Kf x m
where ΔTf is the lowering of freezing point, i is the Vant Hoff factor and m is the molality of the solution.
Here we need to lower the freezing point to -10°C so that the water in the radiator does not freeze.
So, the change in freezing point will be 10
Here i will be 1 since we are not taking any salt or ionic compound
Molality (m) = Moles of solute / Mass of solution in kg
Moles of solute = Mass of solute given / Molar mass of solute
Here solute is ethylene glycol with formula C₂H₆O₂
The molar mass of ethylene glycol = 2x the Molar Mass of C + 6x the Molar mass of H + 2x the Molar mass of O
The molar mass of ethylene glycol = 2x12 + 6x1 + 2x16
= 62units
Moles of ethylene glycol = a/62
m =
m =
10 = 1 x 1.86 x
a = 10000/3
a = 333.34
Therefore, the mass of ethylene glycol required is 333.34g