Question

KCl is an ionic salt with a formula weight of 74.54 g/mole. A 1.417 M (mole/liter) KCl solution has a density of 1064.5 grams/liter at 20.0 OC. Use the Molarity and the formula weight to find the mass (g) of salt in one liter. Then, find the mass (g and kg) of water in one liter of the solution as the difference between the solution mass and the KCl mass. Include the conversion factor. Determine the molality (m), or moles of salt per kg of water, by dividing the moles of salt in one liter by the kg of water in one liter. Show all units and use proper significant figures. (

Answer 1

Mass of the salt: 105.6g of KCl.

Mass water: 958.9g of water.

Molality: 1.478m.

Step-by-step explanation:

Mass of the salt:

In 1L, there are 1.417 moles. In grams:

1.417 moles KCl * (74.54g / mol) = 105.6g of KCl

Mass of the water:

We can determine the mass of solution (Mass of water + mass KCl) by multiplication of the voluome (1L and density 1064.5g/L), thus:

1L * (1064.5g / L) = 1064.5g - Mass solution.

Mass water = 1064.5g - 105.6g = 958.9g of water

Molality:

Moles KCl = 1.417 moles KCl.

kg Water = 958.9g = 0.9589kg.

Molality = 1.417mol / 0.9589kg = 1.478m