Question

Suppose you wanted to know how many grams of KCl would be left if 350mL of

a 2.0M KCl solution were evaporated to dryness.
b. How would heating the solution affect the mass of KCl?

Answer 1

To find the mass of KCl left after evaporation, multiply the volume of the solution by its molarity, and then use the molar mass to convert moles to grams. For 350 mL of a 2.0M KCl solution, the mass of KCl left would be 52.185 grams. Heating affects only the solvent (water) and not the mass of KCl, assuming there is no decomposition.

Step-by-step explanation:

To determine how many grams of KCl would be left after evaporating 350 mL of a 2.0M KCl solution to dryness, you would need to calculate the mass of KCl that was originally in the solution. Calculate the number of moles of KCl present by multiplying the volume of the solution by the molarity (2.0 moles/L). Then convert moles to grams using the molar mass of KCl (74.55 g/mol).

Calculation steps:

1. Moles of KCl = Volume (L) × Molarity (mol/L)
2. Mass of KCl (g) = Moles of KCl × Molar Mass of KCl (g/mol)

For 350 mL of a 2.0M solution:

1. Moles of KCl = 0.350 L × 2.0 mol/L = 0.70 moles
2. Mass of KCl = 0.70 moles × 74.55 g/mol = 52.185 g

Upon heating the solution, the water will evaporate, but the mass of KCl will not be affected by the heat and will remain the same as long as the KCl does not decompose or react at the heating temperature.

Answer 2

52.2g of KCl would be left

The mass of KCl will remain despite the solution is been heated

Step-by-step explanation:

When you are heating a solution, just the solvent (In this case, water), will be evaporated and, in theory, the mass of KCl will remain despite the solution is been heated.

Now, the mass of KCl that you can obtain from 350mL of a 2.0M solution will be:

Moles KCl:

350mL = 0.350L * (2.0mol / L) = 0.700 moles

Mass KCl -Molar mass: 74.55g/mol-:

0.700mol * (74.55g/mol) = 52.2g of KCl would be left