Question

1)    What mass (in g) of NH₃must be dissolved in 475 g of methanol to make a 0.250 m solution?

2)    How many moles of KF are contained in 244 mL of 0.135 m KF solution?  The density of the solution is 1.22 g/mL

3)    Commercial grade HCl solutions are typically 39.0% (by mass) HCl in water.  Determine the molarity of the HCl, if the solution has a density of 1.20 g/mL.

4)    A solution is prepared by dissolving 49.3 g of KBr in enough water to form 473 mL of solution.  Calculate the mass % of KBr in the solution if the density is 1.12 g/mL.

Answer 1

Concepts and reason

The number of moles of solute present in 1kg of solvent is represented as molality.

Molarity of the solution is defined as the amount of moles of solute present in 1L of the solution.

Mass percent is defined as the mass of one compound which is divided by the total mass of the mixture.

Fundamentals

Molarity of the solution is calculated by:

Molality of a solution is calculated by:

Mass percent of the solution is calculated by:

(1)

(2)

(3)

(4)

Ans: Part 1

Part 2

Part 3

Part 4