calculate the molarity of 0.250 mol of Na2S in 1.85 L of solution.

Answer 1

Hi Hannah!

Molarity can be calculated as the number (#) of moles solute per the # of L solvent. Its units will then be moles solute/liters solution (mol/L). Molarity gives us the concentration of solution so we can determine how potent (or strong) a solution can be.

The solute of a solution is what is being dissolved in the solution, while the solvent is what is doing the dissolving. An example of this would be salt dissolving in water. In this case, salt is the solute while water is the solvent.

In the given reaction, we are told that Na₂S is in solution (the solute) while "the solution" is what the solute is dissolving in (the solvent). We can use this information to calculate molarity:

Molarity (M) = # moles solute/ # Liters solvent

M = (0.250 moles Na₂S)/(1.85L solution)

M = 0.1351351351 moles/L *you can abbreviate moles as mol*

M = 0.135 mol/ L (3 significant figures)

Since M = mol/ L....

Our answer can be expressed as 0.135 M.

Hope this helps! :)