What is the freezing point of water made by dissolving 22.78 g of ethylene glycol (ch2(oh)ch2(oh)) in 87.95 g of water? the freezing-point depression constant of water is 1.86 oc/m.

Explanation:

When a non-volatile solute is added in a solvent then decrease in its freezing point is known as freezing point depression.

Mathematically,    

where       = change in freezing point

                      = freezing point depression constant

                           m = molality

First, calculate the number of moles as follows.

                       No. of moles =

                                             =

                                             = 0.367 mol

Now, it is given that mass of solvent is 87.95 g. As there are 1000 grams in 1 kg.

So,           = 0.08795 kg

Hence, molality of the given solution is as follows.

                   Molality =

                                 =

                                 = 4.172 mol/kg

Therefore, depression in freezing point will be as follows.

            =

Since, freezing point of pure water is . Now, putting the given values as follows.

                =

                                         =

Thus, we can conclude that the freezing point of water in the given mixture is .

c) should be the answer.