Assuming complete dissociation of the solute, how many grams of KNO3 must be added to 275 mL of water to produce a solution that freezes at −14.5 ∘C

108.43 grams KNO₃

Explanation:

To solve this problem we use the formula:

Where

We solve for b:

Using the given volume of water and its density (aprx. 1 g/mL) we calculate the necessary moles of KNO₃:

Finally we convert KNO₃ moles to grams, using its molecular weight:

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.