How can I calculate freezing point depression of water?

Hint: The general formula for water is ${{H}_{2}}O$ , where H is the chemical symbol for hydrogen, O is the chemical symbol for oxygen.

Complete step by step answer:
Molality is defined as the number of moles of solute which is dissolved in one kilogram of solvent. The term molality is denoted by the symbol m. The formula of molality is given below.
Molality =$\dfrac{moles\text{ of solute}}{ki\log rams\text{ of solvent}}$
The formula for the calculation of freezing point depression of water is:
\[\Delta {{T}_{f}}=i{{K}_{f}}m\]
Where, $\Delta {{T}_{f}}$ is the freezing point depression
I is the van’t Hoff factor
And, ${{K}_{f}}$ is the molal freezing point depression constant for the solvent
And m is the molality of the solution.
We can calculate the freezing point depression of water by using the above formula.

Additional Information :
To calculate molality from molarity we will require the density of the given substance. If the density is given then it is easy to calculate molality from molarity. Density is defined as mass per unit volume. With the use of density, we can calculate the kilograms of solvent using the litres of solution.
\[density=\dfrac{mass}{volume}\]

Note: Do not get confused between the term molarity and molality. Molar solution is also known as molarity. Molarity is one of the standard expressions of solution concentration. The molar solution used the gram molecular weight of a solute in calculating molar concentration present in per litre of the solution. Molarity is denoted by the symbol M. The formula of molarity is given below:
molarity = $\dfrac{\text{moles of solute}}{liters\text{ of solution}}$