Molarity

[Jonathan Marcial Dis 1K]

How do we solve for molarity when we are given the amount of a solute in grams and then adding even more water? For example... "A solution is prepared by dissolving 55.1 g of KCl in approximately 75 mL of water and then adding water to a final volume of 125 mL. What is the molarity of KCl(aq) in this solution?" I don't understand how to get the final answer.

[Alexander Hari 1L]

I think in this problem, you need to convert the initial grams to moles and then multiply by the initial volume (75mL) and then set it equal to Mfinalx125mL since MinitialVinitial=MfinalVfinal, then solve for Mfinal

[Chem_Mod]

1. Find the concentration of KCl in the 75 mL solution
2. Set concentration you find in step 1 as M1. V1 = 75 mL. V2= Vfinal = (75 + 125 mL). Use the dilution formula to solve for the final concentration.

[Jonathan Marcial Dis 1K]

Okay, this helps! Thank you!