36g of KOH dissolved in 800mL of water. What is the molality of the solution?

0.80m of KOH

Explanation:

Molality is an unit of concentration defined as the ratio between moles of solute and kg of solvent.

In the problem, the solute is KOH and solvent is water.

Moles of 36g KOH - Molar mass: 56.1g/mol - are:

36g KOH * (1mol / 56.1g) = 0.642 moles of KOH

Now, as density of water is 1g/mL, mass of 800mL of water is:

800mL * (1g / mL) * (1kg / 1000g) = 0.800kg of water

Thus, molality is:

0.642moles of KOH / 0.800kg = 0.80m of KOH