How many moles of ethylene glycol must be dissolved in 500 g of water (Kf = 1.86) to lower the freezing point to -5.00 0C?
delta T = Kf*molality
Plug in 5.00 C for delta T, 1.86 for Kf and calculate molality.
Then molality x kg solvent x molar mass = grams.
You know molality, kg solvent, and molar mass. Calculate grams.
Post your work if you get stuck.
delta T = Kf*molality
Plug in 5.00 C for delta T, 1.86 for Kf and calculate molality.
Then molality x kg solvent x molar mass = grams.
You know molality, kg solvent, and molar mass. Calculate grams.
molar mass? where did u got the molar mass from ?
answered above.
To determine the number of moles of ethylene glycol needed to lower the freezing point of water, we can use the formula:
ΔT = Kf * m
where ΔT is the change in freezing point, Kf is the molal freezing point depression constant, and m is the molality of the solute.
In this case, the freezing point is lowered by -5.00 0C, so ΔT = -5.00 0C. The molal freezing point depression constant for water is 1.86 °C/m.
We need to find the molality of the solute, so we need to calculate the number of moles of ethylene glycol and determine the mass of water.
First, we need to convert the change in freezing point from Celsius to Kelvin:
ΔT(K) = -5.00°C + 273.15
Now, let's calculate the moles of ethylene glycol:
n = m/M
where n is the number of moles, m is the mass of the solute, and M is the molar mass of ethylene glycol.
The molar mass of ethylene glycol (C2H6O2) is:
M = 2 * molar mass of C + 6 * molar mass of H + 2 * molar mass of O
Now, we can calculate the mass of water:
mass of water = 500 g
Now, we can calculate the molality of the solute:
m = n / (mass of water in kg)
Finally, we can substitute the values into the formula:
-5.00 0C = 1.86 °C/m * (n / (mass of water in kg))
Now, we can rearrange the equation and solve for n:
n = (-5.00 0C) * (mass of water in kg) / (1.86 °C/m)
By following these steps, you can find the number of moles of ethylene glycol required to lower the freezing point to -5.00 0C in 500 g of water.