Asample of sea water taken from the atlantic ocean freezes at -2.14 degree celsius and a sample taken from the arctic ocean freezes at -1.96 degree celsius. what is the molality of salt in each seawater sample? (assume the only solute in each sample is sodium chloride)

(a) 0.575 m;

(b) 0.527 m

Explanation:

Let's use the freezing point depression law in each of these cases.

(a) According to the law:

Rearrange the equation for molality, b:

NaCl is an ionic substance, 1 mole of it dissociates into 2 moles of ions, sodium ion and chloride ion, this means the van 't Hoff factor i = 2.

Here:

is the initial freezing point of water,

is the final freezing point of water.

For water:

Applying the equation

(b) Applying the same equation for the same salt and the same conditions, except a new freezing point, we would expect to obtain:

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