If the radiation of an automobile contains 12L of water, how much would the freezing point be lowered by addition of 5 kg of prestone (glycol, C2H4(OH2))? How many kg of zerone (methyl alcohol, CH3OH) would be required to produce the same result? assume 100% purity .
5 kg prestone to mole. moles = grams/molar mass, then
moles/12 kg solvent = m
then delta T = Kf*m
CH3OH part done the same way.
I'm sorry, I'm not sure what you mean by "Bbnn". Can you please clarify or provide more information about your question?
Here we have to find ∆Tf.
And it is kf * m
So kf = 1.86
And m = 5000/62/12
Solve and get ur ans i.e ∆Tf = 12
To calculate the decrease in freezing point caused by the addition of a solute, we can use the concept of molality (m).
The formula to calculate the freezing point depression (ΔTf) is given by:
ΔTf = Kf * m
Where:
- ΔTf is the change in freezing point,
- Kf is the cryoscopic constant (which depends on the solvent),
- m is the molality of the solute (moles of solute per kilogram of solvent).
First, let's solve for the amount of freezing point depression caused by the addition of 5 kg of Prestone (C2H4(OH)2) to 12 liters of water.
Step 1: Convert the volume of water from liters to kilograms.
Since 1 L of water weighs approximately 1 kg, 12 L of water weighs 12 kg.
Step 2: Calculate the molality of Prestone in water.
Molar mass of Prestone (C2H4(OH2)) = 62.07 g/mol
Mass of Prestone = 5 kg = 5000 g
Using the formula: m = moles solute / kg of solvent
Number of moles of Prestone = Mass of Prestone / Molar mass of Prestone
m = (5000 g / 62.07 g/mol) / 12 kg
Step 3: Calculate the decrease in freezing point (ΔTf).
To find the cryoscopic constant (Kf) for water, we need to search for it in a reference database or use the values provided in the question.
Let's assume the cryoscopic constant (Kf) for water is 1.86°C/m.
ΔTf = Kf * m
ΔTf = 1.86 °C/m * [(5000 g / 62.07 g/mol) / 12 kg]
Calculate the value of ΔTf using the given formula and the calculated value of moles of Prestone.
Next, let's determine the amount of Zerone (CH3OH) required to produce the same decrease in freezing point.
Step 1: Convert the decrease in freezing point (ΔTf) to molality (m).
m = ΔTf / Kf
Step 2: Calculate the mass of Zerone required.
Molar mass of Zerone (CH3OH) = 32.04 g/mol
Using the formula: Mass of Zerone = molar mass * m * kg of solvent
For this calculation, we will assume 100% purity of Zerone.
Mass of Zerone = 32.04 g/mol * m * (12 kg + 5 kg)
Calculate the mass of Zerone required using the given formula and the calculated value of molality.
Remember to always check the units and perform the calculations accurately to obtain the precise results.